'PB82126806 1111111111111111111111111111111
u.s. Department of Transportation RailroadC lassi.fication Federal Railroad Administration Yard Technology Manual
Office of Research and Development Volume II: Yard Computer Washington, D.C. 20590 Systems
. "
FRA/ORD-81/20.11 Neal P. Savage Document is available to August 1981 Paul L. Tuan the U.S. public through Final Report Linda C. Gill the National Technical Hazel T. Ellis Information Service, Peter J. Wong Springfield, Virginia 22161 ------, • R£PROOUC£D BY i I, NATIONAL TECHNICAL ! I INFORMATION SERVICE 1 : u.s. D£PAIITM£HT OF COMM£RC£ ISPRIIIGfIUD. VA 22161 . -'-' ~-..:...--.----.~ ------NOTICE
This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of informa· tion exchange. The United States Govern ment assumes no liability for the contents or use thereof.
NOTICE
The United States Government does not endorse products or manufacturers. Trade or manufacturers' names appear herein solely because they are considered essential to the object of this report. Technical Report Doculllentatlon Pale 3. R.clplent·. Catalog No. FRA/ORD-8l/20.II 5. Repor' O.te August 1981 Railroad Classification Yard Technology Hanual- Volume II: Yard Computer Systems
1--::--_~:-:-______-18. Perfor",!ng O'gonilOtion Rep.r, No. 7. Author'.) N. P. Savage, P. L. Tuan, L. C. Gill, SRI Project 6364 H. T. Ellis, P. J. Wong 9. Pe,fo""lng O,,,.,llolion Nome and Addre .. 10. Work Unit No .. (TRAIS) SRI International * 333 kavenswood Avenue 11. C.ntract or Gr.nt No. Henle Park, CA 94025 DOT-TSC-1337 13. Type.f Report .nd Peri.d Co"e,ed ~------~------~12. Spon.o,'ng Agency Name .nd Addre .. Department of Transportation Final Report Federal Railroad Administration Office of Research and Development 400 7th Street, SW., Washington. D.C. 20590 15. Supplement.,y Note. U.S. Department of Transportation Transportation Systems Center *Under contract to: Kendall Square / Cambridge MA 02142
This volume {Volume II) of the Railroad Classification Yard Technology Manual
documents the railroad classification yard computer systems methodology.
The subjects covered are: functional description of process control and
inventory computer systems, development of computer system requirements,
economic analysis, and computer systems acquisition, installation, and management.
Volume I concerns the physical design of railroad classification yards. ~ - " (FRA/ORD-81/20.1)
17. I 19. Security CI ...,f. (.f th,. report) 20. S.cu,'ty CI ...,f. (of thl. p ...l 21. No. of POle. 22. P,'ce Unclassified unclassified 1.~(P Fonn DOT F 1700.7 (8-72) Reproduction of complet.d pal. authorized METRIC CONVERSION FACTORS 9 23 Approximate Conversions to Metric Measures Approximate Conversions from Metric Measures -- 22 ..... ; ~ Symbol When You Know Multiply by To Find Symbol Symbol When You Know Multiply by To Find Symbol 21 " 8 ~ 20 LENGTH;. LENGTH - 19 mm millimeters 0.04 InchM in em centimeters 0.4 inches in in inches ~.6 centimeters em 7 18 m meter. 3.3 taat ft ft teet 30 centimeters cm =-- m meters 1.1 yerds yd yd yards 0.9 maters m - 17 km kilometers 0.6 milM mi mi miles 1.6 kilometer. km - 16 AREA AREA 6 - 16 em2 square centimeters 0.16 square inches in2 in2 squere inches 6.6 square centimeters crn2 m2 square meters 1.2 squere yards yd2 ft2 square teat 0.09 square meters rn2 _ krn2 squere kilometers 0.4 squere mile. mi2 yd2 squere yards 0.8 squara meters rn2 14 ha hectare. (10,000 rn21 2.5 acres mi2 square miles 2.6 square kilometers km2 acres 0.4 hectares ha 6 - 13 ~: MASS (weight) MASS (weight) - 12 --- g grams 0.036 ounces oz oz ounces 28 grams g - 11 . Ib d 045 k'l k kg kilograms 2.2 pounds Ib POhun s 0'9 lograms g tonnas(1000kgl 1.1 short tons s ort tons . tonnes 4 - 10 (2000 Ib) VOLUME = 9 VOLUME tsp teaspoons 5 milliliters ml 8 ml milliliters 0.03 fluid ounces fI oz Tbsp tablespoons 16 milliliters ml 3 I liters 2.1 pints pt fl oz fluid ounces 30 milliliters ml _ 7 I litars 1.06 quarts qt c cups 0.24 liters I liters 0.26 ganons gal pt pints 0.47 liters _ m3 cubic meters 36 cubic feat ft3 qt quarts 0.95 liters 6 m1 cubic meters 1.3 cubic yerds Vd1 gal gallons 3.8 liters I tt3 cUb:c fcot 0.03 cubic meters m3 2 - 5 TEMPERATURE (exact) yd1 cubiC vards 0.76 cubic meters m3 TEMPERATURE (exact) - 4 0C Celsius 9/5 (than Fahrenheit OF temperatura add 321 temperature OF Fahrenheit 5/9 (after Celsius 0C - 3 temperature subtracting temperature OF 32) - 2 OF 32 98.6 212 -40 0 140 80 ~ 120 160 2001 ·1 In. ~ 2.64 c,...:;(;x;Ctlyl. For other exact conv... lon •• nd mora detail tab'e,,,. - I I ~ ,I II I I I I ,I I, I, I II I I I II I, I II ' NBS Misc. Pub •. 286. Unite of Walght and MeaauraL Prlca$2.25 SO Catalog -40 -20 20 40 60 80 100 No. C13 10286. inches - cm °C 0 37 °C PREFACE This work was performed by members of the Transportation Operations and Information Systems Center of SR! International for the Department of Transportation's Transportation System Center (TSC), Cambridge, Massachusetts. Dr. John Hopkins of the TSC was technical monitor of the project (under Contract DOT-TSC-l337). The effort was sponsored by the Office of Freight and Passenger Systems, Federal Railroad Administration (FRA), as part of a program managed by Mr. William F. Cracker, Jr. The research was performed under the supervision of Dr. Peter J. Wong, Director, Transportation Operations Research Department. Mr. Neal P. Savage'was the project leader. Dr. Paul L. Tuan provided expertise in the areas of process control systems, computer configuration designs, and management structure considerations. Ms. Linda C. Gill and Ms. Hazel Ellis provided technical assistance in the collection, analysis, and synthesis of computer systems literature on process control systems and computer systems acquisition and implementation. Appreciation is expressed to the following for their cooperation and inputs: Mr. John McGinley (Potomac Yard, RF&P), Messrs. Dean Johnson and John Clendenon (Southern Pacific), Don Hatcher and Jack Lewis (Union Pacific), Phil Seifert (Missouri Pacific), and Larry Trenga and Thomas Levine (Westinghouse Air Brake Company). r - --...._~ / --I' i iii CONTENTS PREFACE • l.l.l. LIST OF ILLUSTRATIONS • Vl.l. LIST OF EXHIBITS l.X LIST OF TABLES Xl. 1 INTRODUCTION • 1 1.1 Background 1 1.2 Purpose of this Manual 1 1.3 Focus on Yard Inventory and Process Control • 1 1.4 Case Study 2 1.5 Organization of the Manual 2 2 COMPUTER PRIMER 3 2.1 Overview 3 2.2 Major Types of Digital Computers 4 2.3 Hardware 5 2.4 Software 10 2.5 Network Organization 15 3 OPERATIONS AND FUNCTIONS OF THE YARD INVENTORY SYSTEM 19 3.1 Railroad Operational Description 19 3.2 Computer Functions 29 4 OPERATIONS AND FUNCTIONS OF THE PROCESS CONTROL SYSTEM • 43 4.1 Railroad Operational Description 43 4.2 Computer Software Functional Description 46 4.3 Level of Automation • 55 5 SYSTEM DESIGN 57 5.1 Survey Phase 58 5.2 Analysis Phase 59 5.3 Software Design Phase • 82 5.4 Hardware Study 84 I Preceding page brank ! v '------=-=.J 6 ACQUISITION AND IMPLEMENTATION OF COMPUTER SYSTEMS 93 6.1 Procurement Process • • • • • • • .'. • • •• 93 6.2 Software Development and Testing • • • • •• • • 95 6.3' Development of Acceptance Test Plan, Specification:s~ Procedures, and Test Data. • ••••••• 95 6.4 System Documentation • • . • •• • 95 6.5' User Training • • • • • • • • • ~ 96 6.6 Site Preparation • • • • • 96 6.7 System Conversion . ' . 97 6.8 Acceptance Test and System Installation • ~ • ~ ~ •• 97' 7 OPERATION AND MANAGEMENT OF COMPUTER SYSTEMS . '. 99 7.1 Computer Personnel Orga~ization • • • • • •• 99·, 7.2 Recruitment and Training of Professionals • • . • • 100 7.3 Operat~ng Procedu~es • • • •• • •••••••••• 101 7.4' System Maintenance • • • • •• •• • • • ~ • • • 101 7.5 Method of Day-to-Day Monitoring and Control ••• 101 REFERENCES AND BIBLIOGRAPHY 103 APPENDICES A CLASSIFICATION YARDS AND THEIR OPERATIONS . . ,. . . . , A-l B CURRENT COMPUTER INSTALLATIONS SURVEY . • ~. . • . . _.. B-1 vi ILLUSTRATIONS 2-1 Functional Hardware Units • • • • • • • • • • • • . . . 4 2-2 Memory Price and Access Time Comparison • • • • • • .• • • 6 2-3 Configuration of Hot-Standby Dual-Processor System 9 3-1 Yard MIS Functions • • •••. ' • • • • • • • • • • • 30 3-2 Three Inventory File Structures • • • • • • • • • . . . . 36 4-1 Classification Yard Process Control Software System 47 • 4-2 Example of a Distributed Retarder Control System j 54 5-1 System Design Cycle •• • •• 57 5-2 Implementation Cycle • • • • • • • • • • • • • • • • • • 59 5-3 Sample Critical Path Diagram. • ••• 60 5-4 Structured Analysis Steps • • • • •••••• 61 5-5 Flow Diagram of Waybill Procedures from Case Study Yard ••• 61 5-6 Sample Matrix of Functions and Quantifiers for Structured Analysis •• • • • • • • • • • • • • • 62 5-7 Current Computer Programs at Case Study Yard • • • • • • 62 5-8 Flowchart of Future Clerical Operations at Case Study Yard • • 64 5-9 Yard Inventory Subsystem at Case Study Yarq • • • • • • 66 5-10 New Management Information System Programs at Case Study Yard ••••••••••••••••••••••••• 67 5-11 System Interfaces ••••••••••••••••• 68 5-12 Sample Hardware Configuration from Case Study Yard • 69 5-13 Sample Data Flow Diagram of Current Operations from Case Study Yard ••• • • • • • • • • • • • • • • 69 ·5-14 Sample Data Flow Diagram of Future Operations from Case Study Yard ••••• • • • • • ••• ,. • • • • 70 5-15 Example of Division of Functions to Develop a Configuration 73 5-16 Configuration of a Centralized Yard Computer System • • • • • 73 5-17 Configuration of a Decentralized Yard Computer System •• 74 5-18 Configuration of a Regionalized Yard Computer System • 75 5-19 Functional Allocations of Each Alternative Configuration for Case Study Yard ••• • • • • • • • • • • • • • • 76 5-20 Sample Queuing Model of Processor Servicing ••••• 85 5-21 Sample Configuration Model • • • • • • • ••• 85 A-l Example of a Flat Yard Track Configuration • • A-l A-2 Schematic Representation of a Hump Yard •••• A-2 A-3 Car-Handling Processes in Classification Yards A-3 EXHIBITS 3-1 Sample Car Inventory by Block Number 20 3-2 Sample Computer-Generated Switch List · · · · · · 21 3-3 Sample Tonnage Report · · · · · · · · 22 3-4 Sample Four-Hour Report · · · · 23 3-5 Sample Track Inventory Inquiry· · · · · · · · · · · · 24 3-6 Sample Track Inquiry Report · · · 24 3-7 Sample Individual Car Inquiry · · · · · · · · · 25 3-8 Sample Dangerous Car Report · · · · · 25 3-9 Sample Car Inquiry 26 3-10 Sample Report of Trains· · Received· · · · and Forwarded· · · · 26 3-11 Sample Report of Cars Handled 26 3-12 Sample Report of Daily Inbound and Outbound· · · · ·Train · Statistics· · · · · 27 3-13 Sample Daily Stop Report · 28 3-14 Yard Management Information· ·Systems · · · · 31 3-15 Sample Inventory File · · · · · 35 3-16 Sample Car Record File · · · · · · · · · · · · 38 3-17 Sample Yard History File· · · · · · · · · · · · · · · · · · · · 40 4-1 Common Process Control Functions· · · · · · · · · · · 44 5-1 Current MIS Programs at Case Study· Yard 63 5-2 Detailed Procedures for New Paperwork Processing at Case Study Yard . . · · · · · · · · · · · 65 5-3 Functional Hierarchy · · · · · · · · · · · · · · · · · 71 5-4 Sample Cost/Benefit Work Sheet · · · · · · · · · · · · · 78 6-1 RFP System Spec ificat ions · · · · · · · · · • · 94 I frece~ng page blank J i~,' I' TABLES 2-1 Estimates of Mean Time Between Failures and Mean Time To Repair for Computer Components •• • • • • • d 4-1 Software Routines for Process Control Computer • • • • • 49 5-1 Justification for Process Control Computer Use • • • • • 79 5-2 Justification for Management Information Computer Use •••• 80 B-1 Yard Configurations •• . • • • • •• B-2 B-2 Computer System Configurations • • • • • B-3 B-3 Peripherals Used ••.••• B-4 ------.----, xii Preceding page blank I I CHAPTER 1: INTRODUCTION 1.1 BACKGROUND Consequently, yard computer systems should be designed by a team comprising people experienced The purpose of a railroad classification yard is in yard operations, who provide user specifica to sort (switch) cars from inbound trains into tions, and computer specialists, who design the classifications (blocks) and to build outbound computer system that meets these specifications. trains by suitably grouping specific classifi Because the operations personnel and the computer cations of cars. The classification process en specialists view the problem from different per tails considerable physical movement of trains, spectives and training, however, communication cars, engines, and crews between receiving between them can sometimes be difficult. This tracks, classification tracks, and departure may result in a yard computer system that does tracks. Associated with this physical movement not have the features the user wanted and/or a of cars are the processing of paperwork on each system that has features the user does not want. car (e.g., waybills), an inventory system to Such a system is not easy to use, does not pro monitor the location of each car, and the control vide the information or performance desired, and of the routes and speeds of engines and cars.* can be more expensive than necessary. These management and control functions have evol ved from labor-intensive manual systems to highly These problems can be ameliorated if operations automated computer-based systems that can greatly personnel become more familiar with computer increase the throughput and productivity of the systems technology and if computer specialists yard. become more familiar with the operational re quirements of classification yards. The purpos.e A recent study (Petracek et al., 1976) indicates of this manual is to provide operations person that over the next 25 years major rehabilitation nel and computer specialists with that familiar projects will be carried out at 200 classifica ity by detailing practical guidelines, proce tion yards. At many of these yards, the moderni dures, and principles for use in determining the zation plan will include the installation of new requirements, specifications, and design of yard yard computer systems to replace current manual computer systems. systems or to upgrade existing computer systems. When both hardware and software costs are con 1.3 FOCUS ON YARD INVENTORY AND PROCESS CONTROL sidered, the computer systems for a yard repre sent a major capital expenditure. Included among the many computer systems in a classification yard or terminal are those for: In view of their influence on yard throughput and productivity and the capital investments in • Process control them, yard computer systems are an important aspect in the design of classification yards. • Yard inventory ·1.2 PURPOSE OF THIS MANUAL • Waybills The operations of a classification yard are com • Accounting plex, involving the operations and coordination of the terminal superintendent, trainmaster, • Payroll train dispatcher, crew dispatcher," yardmaster, clerks, engine crews, inspection crews, and • Demurrage others. The operations of a particular yard reflect the railroad's management philosophy, • Crew scheduling. local labor agreements, and the historical pat tern of performing work at the yard. Thus, com Treating all these computer systems ~s beyond puter systems designers often have difficulty in the scope of this manual. Rather, attention is understanding the operational needs in a yard. restricted to the process control and yard in ventory systems and their interface with the Computer systems, too, are complex, and design systemwide car location and car record system. ers often must make sophisticated trade-offs in The process control (PC) computer system con hardware and software design options. A person trols the speed of cars in a hump yard and "routes not trained in computer technology cannot make cars to the proper classification tracks by auto informed decisions easily. matically throwing switches. The yard inventory system monitors the location of cars and trains as cars are moved from track to track, monitors the status and availability of tracks, stores *This volume assumes that the reader is familiar information about each car (the car record) and with classification yards and their operation. produces the information and paperwork necessary Appendix A is provided for readers who do not for carrying out the classification and train have this familiarity. building process. The yard inventory system is often referred to as the yard management railroad personnel with computer systems, Chap information system (MIS). ter 2, A Computer Primer, describes major aspects of computer hardware and software. No specific In this manual, we use the term "yard MIS" speci railroad applications are discussed. fically for the yard inventory system. This is a restrictive use of the term because it can Chapters 3 and 4 describe the operations and encompass all the other yard computer systems functions of yard inventory systems and process listed above (except the PC system). Similarly, control systems. Each chapter has two major we use the term "systemwide MIS" specifically to sections, the first describing the operation of denote the systemwide car location and car record the MIS or PC system within the context of nor system. Again, this is a restrictive use of the mal yard operations and the second describing in term because such functions as systemwide payroll greater detail the individual functions of each and accounting could be included in the system system. These descriptions cover the input and wide MIS. output of each function as well as the proces sing completed. 1.4 CASE STUDY Chapters 5, 6, and 7 discuss design, implementa To assist in the development of the methodology tion, and management of classification yard com and ensure its practicality, SRI conducted a yard puter systems. Chapter 5, System Design, des computer system case study for the Potomac Yard cribes the steps in designing a computer system- of the Richmond, Fredericksburg, and Potomac survey, analysis, software design, and hardware Railroad (RF&P). The case study effort involved study. Chapter 6, Computer System Acquisition the evaluation of the yard traffic capacity, and Implementation, describes system procurement, ,development of computer systems requirements, . software development, and system installation. analysis of alternative hardware configurations, Chapter 7, Systems Operation and Management, dis assessment of benefits from upgrading the com cusses some aspects of ongoing computer systems puter systems, and recommendations for system management. implementation and installation~ Much of the information and procedures developed in the case To present a general discussion of classification study have been incorporated into this manual. yard computer systems, the authors have attempted to select, when possible, representative examples 1.5 ORGANIZATION OF THE MANUAL and references from classification yards. Of the many automated classification yards (an installa This volume of the Railroad Classification Yard tion survey is presented in Appendix B), only a Technology Manual discusses the use of informa small number have been represented. Yard com tion and process control computer systems in puter 3ystems vary greatly from yard to yard; railroad classification yards. To familiarize therefore, all examples are in some way site specific. 2 CHAPTER 2: COMPUTER PRIMER 2.1 OVERVIEW multiple functions. The microprocessor could be manufactured at a cost of less than $10. When This computer primer is presented for readers combined with memory chips, a microcomputer could who have limited experience with computer be produced for less than $300. Such a micro systems and for those who wish to review their computer is 20 times faster and has 1/30,000 the knowledge of current computer technology and volume at 1/10,000 the cost of the original ENIAC trends. computer (Noyce, 1977). Unless noted otherwise, the term "computer" Two examples of present chip technology are the refers specifically to stored-program, general chips used in the IBM 4300 series of computers purpose electronic digital computers. A computer and the Intel iAPX 432 microprocessor. The IBM system comprises hardware and software: Hardware chips have 132 solder connections, as compared is the physical equipment, such as mechanical, with the normal DIP, which has 16 to 40 connec electronic, and magnetic units; software is the tions. These IC chips have 7,000 components set of computer programs that direct the hardware with 3-nanosecond transistor-transistor logic to complete an application or task. (TTL) or 14,000 components with 1.5-nanosecond emitter-coupled logic (ECL). The memory chips 2.1.1 History in these microprocessors are 18K, 32K, or 64K random-access memory (RAM) with 140/285-, The first generation of computers (1945-1958) 280/470-, or 440/980-nanosecond access/cycle began with ENIAC, the first all-electronic speeds. This technology allows four 64K RAM calculator. This machine was developed using chips to be mounted on a l-inch-square module vacuum tubes for signal amplification and for (Stein, 1979). logic operations. Mercury delay lines and cathode ray tubes (CRTs) were used for memory. The recently announced iAPX 432 is a 32-bit ENIAC contained no internally stored programs. microprocessor integrating 200,000 transistors. UNIVAC I (Universal Automatic Computer) became It has a 16 million-byte physical address and the first commercially available computer in has a virtual address space of 1 trillion bytes. 1953. This computer contained an internally The CPU is capable of completing up to 2 million stored program and used crystal diodes for most instructions per second, comparable to an IBM logic circuits (Huskey, 1970). 370/158 (IEEE Micro, 1981). The second generation of computers began in late 2.1.2 Hardware 1958. The translator replaced the vacuum tube as an amplifier, and magnetic cores replaced The physical equipment that constitutes a mercury delay lines and CRTs as memory. Transis computer may be divided into the following tors are advantageous because they are solid functional units (Couger & McFadden, 1975): state components that require little power and offer greater reliability than vacuum tubes • Input devices--Receive data and move it (Kenney, 1978). into main memory. The third generation of computers evolved after • Storage (or memory) devices--Store data 1965 when discrete components were replaced by and instructions. solid-state circuits. All diode and transistor components were placed on single silicon chips, • Control devices--Regulate and control and the packaging of integrated circuits (ICs) the elements of the computer system. was standardized as the dual in-line package (DIP) (Long, 1977). The IC is sealed in a • Arithmetic/logic (A/L) units--Perform plastic or ceramic enclosure, and connections arithmetic operations and logical are implanted that lead to the enclosure sides. comparisons. The single most noticeable advance of the early • Output devices--Transmit or display the 1970s was the Intel 4004 microprocessor chip results of the computer processing. (Long, 1977). Up to that time, each specific application was designed independently, and These five units are further defined by physical logic and memory chips and other components were location, as shown in Figure 2-1. The CPU con permanently wired together for one application. sists of the control unit, A/L unit, and main Instead of fabricating a specific design into memory. Mass memory, input devices, and output the integrated circuit chip, Intel inscribed an devices are classified as peripherals. For main entire central processing unit (CPU) on a single memory, magnetic core or MOS (metal-oxide semi silicon chip. When attached to memory chips, conductor) and other technologies are used. Mass the microprocessor (CPU on a chip) became a memory devices include magnetic disk units, mag general-purpose microcomputer, programmable for netic tapes, magnetic strips, and mass storage 3 COMPUTER SYSTEM CENTRAL PROCESSING UNIT ARITHMETIC/ CONTROL UNIT LOGIC UNIT PERFORMS SUPERVISES CALCULATIONS ALL COMPUTER AND LOGIC FUNCTIONS COMPARISONS , ' MAIN MEMORY STORES INSTRUCTIONS AND DATA / INPUT DEVICES / / MASS MEMORY / / OUTPUT DEVICES / / INFORMATION / EXAMPLE: : / EXAMPLE: EXAMPLE: TAPE, DISK, CRT, , I CARD READER / TAPE / / PRINTER - - -- \ YDATA / PREPARATION .. FLOWOF DATA \: EXAMPLE: KEY-TO-DISK,l CARD PUNCH Source: Couger and McFadden (1975), FIGURE 2-1, ,FUNCTIONAL HARDWARE UNITS systems. Input devices include keyboards, 2.2.1 Generality of Application punched card and tape readers, and magnetic and optical character readers. Output devices in The first major feature used to classify com clude CRT displays, card and tape punches, and puters is generality of application. A computer printers. Magnetic tape and disk memories can that is designed or packaged for a limited set act as both input and output devices. of specific uses may be classified as a special purpose computer. Examples of such computers 2.1. 3 Software are PC systems, environmental control systems, electronic games, communications controllers, The two basic kinds of software are system and office systems, and retail sales systems. Com application (Huskey, 1970). System software puters designed to be applicable for a wide comprises operating system programs that control range of uses are classified as general-purpose (operate) the computer, language compilers and computers, these computers are often packaged by assemblers that translate user-generated software nature of application. Many manufacturers, into machine code (instructions), and utility develop two computers of approximately the same routines _(system diagnostics, program debuggers, size but for different markets. Scientific libraries, editing routines, and file management machines are designed to process large quan systems)., Application or user programs are high tities of numerical data, often in a real-time level-language programs that are developed to environme'nt" fed by remote instrumentation. They complete a specific user task. Most _users deal are programmed in user-oriented languages such primarily with these application ,programs. as FORTRAN (the most common), APL, and PASCAL. 2.2 MAJOP_ TYPES OF DIGITAL COMPUTERS Commercial data processing systems are designed for business applications. They must be capable Computers are categorized into major types by of manipulating large data files and of their generality of application and size. receiving information from many remote data 'entry terminals. Commercial systems are often used for management information and financial 4 accounting programs and use specialized nanoseconds and is based on a 64-bit chip. Its languages such as COBOL. purchase price is approximately $250,000 (Blumenthal, 1979). The upper price limit for 2.2.2 Size "medium-size" computers in 1')80 was approxi mately $900,000. Computer size can be measured by price, word size, memory size, processing speed, and func Large computers include the IBM 303X series. The tional design. With the dramatic changes in model 3033 has a 4 to 16 MB memory capacity and technology and price that occur each year, a 57-nanosecond machine cycle time (Blumenthal, classification increasingly is based on func 1979). Recently, larger dual-processor config tional design. [For the last 25 years, cost/ urations have been announced. performance ratios have improved at an annual compounded rate of 25% (Stein, 1979).] For The last classification of computers is a group example, at one time, microcomputers cost be of special-purpose "super-computers." Pipeline tween $100 and $1,000 (Kenney, 1978), but with processors use multiple and independent CPUs on high-volume production the prices have dropped a single data stream, and array or parallel 100-fold. The TMS 1000, the computer industry's processors use mUltiple CPUs executing the same most popular 4-bit chip, cost less than $1 in instructions on multiple data streams. CRAY I large quantities in 1980. Eight-bit processors and ILLIAC IV are examples of each (Thurber, such as the Intel 8080 and Zilog Z80 cost less 1976; Auerbach Publishers, 1981). than $2. Newer l6-bit processors such as the Intel 8086 and Zilog Z800, now cost about $200 2. 3 HARDWARE but the prices are expected to fall quickly. 2.3.1 Central Processing Units The minicomputer is a general-purpose computer larger than the microcomputer. It can perform The primary functional unit of e~ery computer is logical, arithmetic, and input/output (I/O) the CPU. The CPU processes data, supervises the functions under the control of the user. The various other units of the computer, and contains distinguishing characteristic of a minicomputer the main memory. The CPU consists of a control as compared with a microcomputer is its larger unit, an A/L unit, and a storage unit (main memory and increased capabilities. A minicom memory). One or more processors act as logic pute.r can be defined as follows (Kenney, 1978): and control units, and an additional processor may provide storage or I/O control. • It is a general-purpose computer and not restricted to specific applications. The control unit interprets and executes the instructions contained in the program in main • It operates through programming. memory. Data are also stored in the main memory and can be transferred to the A/L unit for • It has a versatile I/O capability. processing. The control unit also moves data and programs in and out of main memory. • The central processor costs less than $25,000. The A/Lunit is used to complete arithmetic operations (addition, subtraction, multipli In recent years, a second minicomputer classifi- cation) and division) and may make logical ··cation was introduced, the "supermini." These decisions for the computer to follow. The time 32-bit computers have the capabilities of the taken to complete A/L unit functions is often mainframe computers of 10 years ago at a fraction used to rate computer productivity or power. of the cost. Representative of these superminis Floating-point arithmetic and trigonometric are Digi ta 1- Equipment I s VAX-ll/780 and Prime I s functions are contained either in software 750. Superminis currently have a maximum main programs or, in special cases, in independent memory size of 2 million to 8 million bytes, a microcoded processors. Instructions that are 600-nanosecond memory cycle, and a cost of microcoded can be completed much more quickly approximately $130,000 excluding memory and than the equivalent software execution. peripherals (Schultz, 1979). An announced SEL 32/87 32-bit minicomputer is reported to be 2.3.2 Word Size three times faster than the VAX computer. A 1M-byte memory, a 16K-byte cache configuration Another major characteristic of a computer is costs approximately $235,000 (Coleman, 1981). its word size. A computer word is the basic internal storage and addressing unit. Word size The difference between medium and large computer is expressed as a number of bits. A bit is one systems is somewhat arbitrary. A medium-size switch or memory location and registers either computer can now be considered to be any computer "on" or "off," 1 or O. Registers usually have a with greater capacity or price than the super length of one word. Operations in the CPU may mlnlS. Many older_medium~size computers may have use the entire word as one unit or may divide a greater cost but poorer performance than the the word into smaller units. The byte (8 bits) newer machines. An upper limit on the medium is the standard unit ·used to express one size category is the IBM 4341 processor. It character. Computers with smaller word sizes is .a 32-bit machine with a 2 to 4 MB (mega- or have less expensive hardware but have limited million-byte) memory capacity. The machine instruction sets and are also constrained when cycle time of the IBM 4341 is 150 to 300 addressing memory. 5 The instruction set is the group of instructions to which the computer can respond. One measure ment of computer processing efficiency is the "add time," the time needed to complete the add 2 instruction. When comparing the instruction 10 t times of computers of differing word sizes, it c ~ is important to realize that smaller machines " BIPOLAR RAM execute smaller, less powerful instruction sets r- and have limited memory-addressing capabilities. iD a: w 0- 2.3.3 Main Memory w U it 10-2 0- Data manipulation and logical decision making :; can only be performed with data and programs W r- til resident in the main memory. Main memories >- til 10-4 require the fast speeds of core and MOS types of >- memories. The speed of memory is rated in terms a: 0 :; of memory cycle time. In recent years, the w price of memory has dropped considerably. In :; 1970, main memory for an IBM 360-65 cost $1.55 10-6 per byte. In 1977, memory for an IBM 360-168 10-9 10-6 10-3 cost 27t per byte and HP 3000 memory cost 9t per ACCESS TIME - second, byte (Reynolds, 1977).' Memory for the IBM 4341, Source: Hodges (1977). announced in January 1979, costs only 1.5t per Note: RAM, Random-access memory byte (Auerbach Reporter, 1979), while 64K-chip CCD, Charge-coupled device add-on memory in the HPIOOO has .dropped to It per byte (Datamation, 1981). FIGURE 2·2. MEMORY PRICE AND ACCESS TIME COMPARISON (1977) 2.3.4 Mass Memory Ma~s memory allows additional information to be memory to maLn memory. Memory-accessing routines stored and remain accessible to main memory but first search the cache memory before moving to~ at a much lower cost than if it were stored in mass memory. If the search is successful (if a the main memory. Information from these devices "hit" is made), the slower speed accesses to mass is transferred to main memory only when directed memory are avoided. The percentage of hits can' and at a slower speed than main memory access. be greater than 90% in some applications. For an "average" FORTRAN application using a computer Secondary or mass memory devices may be cate with a memory cycle time of 600 nanoseconds and gorized as random-access (direct-access) devices a cache access time of 80 nanoseconds, the im or as sequential-access devices. Random-access proved memory cycle time is 240 to 400 nano devices locate information without having to seconds (40 to 70% hits). search through the entire file structure. The information. is found from an address and there 2.3.6 Input/Output Devices fore does not prescribe a set order to data in the file. Sequential-access devices require a Numerous devices are available to communicate sequential search through the file. This may information to computers and receive it from take minutes as compared with seconds with them. They vary significantly in information random-access devices. This relatively slow transfer speeds, hard copy capabilities, user access time excludes sequential-access devices interfaces, and price. Input devices include from most on-line applications. punched card readers, magnetic and optical character readers, CRT display/keyboard input Random-access devices include fixed and moving devices, key-to-disk systems, paper tape readers, head disks, diskettes (floppy disks), and magne and touch-tone telephones. Output devices in tic drum units. Sequential-access storage clude card and paper tape punches; CRT displays; devices include tape drives, cassette tape, and impact, thermal, laser, electrostatic, and ink cartridge tape. As Figure 2-2 indicates, a jet printers; plotters; and microfilm. Magnetic direct relationship generally exists between tape and disk units can act both as input devices access time (memory cycle time) and cost. Con and as output devices (Couger ~ McFadden, 1975; tinuing drops in memory prices make cost trade McGlynn, 1978): offs between semiconductor memory (RAM) and disk memory insignificant in many applications 2.3.7 Interactive Peripherals (Business Week, 1981). Of special interest are I/O devices· used for 2.3.5 Cache Memory interactive communications. Autotransaction terminals are designed for specific applications, Cache memory is an additional high-speed memory such as verifying credit card transactions or of lK to 16K bytes (or more) that is used to ordering merchandise. They contain a limited store the information' most likely to be required number of specified function keys and in some by main memory. It is used.as a buffer to speed cases a small display. The user cannot change the transfer of instructions and data from mass the method or sequence of input (McGlynn, 1978). 6 A second type of interactive device is the sequential slices of time. Each increment of key-to-disk system. The user enters information time is used to transmit part of a different onto a magnetic disk a~ queried on a forma~ted input signal. Each input signal is sampled in screen produced by the internal processor. sequence until the transmission is completed. A CRT terminal and keyboard or teletype provide FUM is simpler and lo.wer in cost and is gener a truly interactive unit, which allows the user ally used for data rates of less than 1,800 bps. and computer to communicate directly. With the Synchronous time division multiplexers are used addition of memory and a microprocessor, this extensively for faster bps "applications (McGlynn, unit becomes an "intelligent" terminal. The 1978). local processor contained in the terminal may provide text editing, input data checking, data Concentrators are similar to multiplexers, but packing and formatting, error control, message the use of storage, queuing, and statistical routing and switching, and in some cases local allocation permit use of fewer communication data processing (McGlynn, 1978). With local lines for the same volume of input. memory, a terminal may store 1,000 or 2,000 characters before sending the information to the Switching processors are used to interface and computer. The computer, therefore, need only switch messages between communications devices communicate with a terminal when it indicates of various line speeds, codes, and protocols. that a message must be sent. This allows the They may also handle message logging, control, computer to spend less time servicing terminals. and reporting of terminal and line usage (McGlynn, 197a). 2.3.8 Data Communications Systems Encode/decode devices encode and decode messages A data communications system is needed whenever for security and for transmission efficiency. data that originate in one 10ca"tiOl; are sent" to another location. Terminals, computers, com 2.3.~.2 Communication Processors. Com munications equipment and channels, _and software munication control lIIay be completed in the main form a data communications system (Couger & computer or externally. If internal, CPU time McFadden, 1975). The five hardware units used and main memory space are needed by the communi in communications systems are terminals, the host catio~s cont~ol program. A typical communica~ computer(s), communications interface devices, tions control program translates code, assembles communication "p"rocessors, and transmission and disassembles characters, queues input and carriers (McGlynn, 1978). output messages, interfaces to remote terminals or computers, recognizes and handles various 2.3.8.1 Communications Interfaces. A communica protocols, and detects and corrects errors tions interface is a hardware component that (McGlynn, 1978): connects the terminal or computer to the trans mission carrier. These devices include modems, To free the required CPU and memory, a second multiplexer/concentrators, switching processors, programmable computer may be used as a communica and encode/decoders (McGlynn, 1978). tions or front-end processor. A communications processor replaces the functions of an internal Modems code and decode digital signals so that communications program and'can also function as voice-frequency lines can carry the informa a multiplexer, concentrator, or switching tion. Modems ~re classified according to their processor. data-carrying rate, expressed as bits per second (bps) or as baud. Bits per second is the number 2.3.~~3 Data Transmission Carriers. A trans of information bits transmitted each second. mission carrier is needed to communicate between Baud is the number of signal' events per second. remote hardware locations. Common carriers, If one transmission signal contains only one offering Che public hire of leased lines, are bit, then 1 baud is equivalent to 1 bps. Modems often used. Services offered are classified by may also be classified as synchronous or bandwidth, which is the rate at which data may asynchronous. Synchronous modems transmit a be transferred. Common bandwidth range"s are continuous, uniformly timed stream of data. (Couger & McFadden, 1975)~ Asynchronous modems transmit groups of data at random intervals (McGlynn, 1978). .• Narrow band--45 to 300 bps. Multiplexers divide the use of communications • Voice band--Voice-grade telephone lines lines so that a single higher speed line can to 9,600 bps. carry information from multiple lower speed sources. The division of the line may be made • Broad band--Coaxial cable or microwave using either time division or frequency division to millions of bits per second. methods. Frequency division multiplexing (FDM) divides a channel into a number of discrete, " A communications line may be a direct leased narrow frequency ranges. Each range (sub line "or an ordinary telephone line. Leased channel) is used to transmit information lines are purchased at a fixed monthly rate, simultaneously using" the total bandwidth. independent of usage, and offer faster response times, a better quality transmission, greater Time-division multiplexing (TUM) divides a privacy, and increased flexibility. Other channel into a number of subchannels using broad-band transmission technologies include 7 satellite transmission and optical fiber System failures can be attributed to hardware transmission (Couger & McFadden, 1975; McGlynn, failure, software failure, operator error, and 1978). environmental errors. Software failures are dis cussed in Section 2.4.6. Hardware failures occur Different protocols (transmission coding) are at the component level. To get beyond the high used to send digital data through transmission failure rate of early component life ("infant lines. They may be classified into two groups, mortality"), most components are run for this asynchronous and synchronous. Synchronous period in the factory. Environmentally produced protocols may be further divided into character-, failures occur less often when the electrical bit-, and byte-oriented protocols. An asynch and thermal environment are maintained within ronous protocol transmits data at a nonuniform the optimal operating range with little variance rate, requiring a start and stop bit for each (Champine, 1978). character ,sent. Because each character is sent instantaneously, no buffer is required at the The method used to provide acceptable reliability terminal or other sending device. A synchronous dep~nds on the type of reliability that may be protocol requires that timing signals be sent attained. Three types are discussed here: The between devices but provides a more efficient prevention of downtime of any kind, the preven- , transmission for higher speed devices because no tion of prolonged periods of downtime, and the added bits are needed for each character protection of the data base (Yourdon, 1972). (McGlynn, 1978). 2.3.9.1 Continuous Performance Reliability. In 2.3.9 Reliability a real-time system requirlng contlnuous perfor mance, no failure of any duration can occur. System reliability is commonly expressed as mean Systems are therefore judged on their MTBF. time between failures (MTBF). For many users, a Redundancy and mUltiprocessing are the methods measure of availability is also important. An used to provide this type of reliability. estimate of availability (A) for each component can be expressed using the MTBF and mean time to For complete redundancy, the system must have repair (MTTR) (Champine, 1978), as follows: two or more of every critical component. When any critical component fails, th'e other compon A = MTBF/(MTBF+MT1R) ents continue to operate (Champine, 1978). For fail-safe redundancy, the failure of anyone Table 2-1 presents the MTBF and MTTR estimates component does not degrade the user response or' for various system components. The availability system capability. Multiple CPUs may b~ required of a system is the product of the availabilities to operate concurrently and poll each other to of the individual components on which the system detect processor errors. If three or more pro relies. Therefore, as the number of critical cessors are running concurrently, they may vote' components increases, the total system avail to determine the defective component. This ability decreases. If a system has 20 inde method provides the best method to assure data pendent components, each with a 99% availability, integrity, as affected by processor error. If the 1Bmpound system availability would be the backup processor is not used for concurrent 0.99 or 82% (Champine, 1978). processing, it may be used for secondary tasks such as batch processing. When the primary processor fails, the secondary processor is TABLE 2-1. - ESTIMATES OF MEAN TIME BETWEEN switched to the primary task. A "fail-soft" FAILURES (MTBF) AND MEAN TIME TO REPAIR (MTTR) system provides continuous processing through FOR COMPUTER COMPONENTS (hours) , incomplete redundancy. A fail-soft system guards against complete system failure, but the level of service is generally degraded when a Unit MTBF MtTR component fails. When a failure occurs, some functions such as batch processing must be Moving-head disk drive 1,000 1 eliminated and a delay in response time may be Fixed-head disk drive 1,500 1 experienced. Disk controller 14,000, 2 Tape drive 1,000 2 A second method to improve reliability is multi Tape controller 20,000 3 processing, whereby no backup system is used. A Processor and console 7,700 1.5 single system is configured with multiple proces 4K core memory 34,700 1.5 sors, main memory, I/O devices, and peripherals. 8K core memory 25,000 1.5 When a component fails, the system is automati Real-time clock 200,000 1 cally reconfigured to continue in a degraded Multiplexer 40,000 1 mode. If an insufficient processing capacity Bus switch 20,000 1 remains, the total system cannot operate at full Arithmetic unit 200,000 1 functional capacity. In this casei the system CRT terminals 2,000 2 sheds noncritical functions until a managea&le Computer with 28K memory 3,500 2 processing load is reached. This method requires a thorough design of system architecture to ensure that sufficient capacity 'remains for all critical functions. This is a fail-soft'hard Source: ,Kenney (1978) • ~ :~ ware configuration because it provides backup processing but does not provide complete 8 redundancy. It is generally less expensive than full computer backup because smaller computers can be used. As the number of redundant components increases, the degree of degradation for each single fail ure decreases (Scherr, 1978). Multiprocessing systems run optimally with mu1titask processing TO MIS COMPUTER loads because single failures then only affect independently run jobs on the system. On the other hand, if the system involves a single task, the failure of a single component may prevent CPU CPU completion of the task. Efficient programming is increasingly difficult as the number of A B mUltiple processors increases. For a given application and total system size, as the number of processors increases, the size needed for each decreases. As the largest unit of proces sing power and memory decreases, the effort to modularize the application to that size and to control intermodu1e communications increases greatly. In addition, as the number of I/O I/O processors increases, the overhead to run them CONTROLLER CONTROLLER also increases. A B At failure, reconfiguration may be by an auto matic or semiautomatic switch. The fastest method is to have a second processor connected to the same memory and communications lines as the first so as to perform the same functions in TO FIELD DEVICES parallel. This configuration is called automatic switchover or hot standby. The primary processor FIGURE 2-3. CONFIGURATION OF HOT-STANDBY DUAL is used as a stand-alone computer to perform all PROCESSOR SYSTEM required functions. The secondary processor is always on hot standby, ready to cut over at any time. Inputs are received by both processors simultaneously, and calculations are made in a redundant manner. However, only the output from computer first updates its status from the check the primary processor is usually allowed to exit; point file. This method reduces the size of the the qutput from the secondary processor is com shared files. The frequency of checkpointing pared with that of the primary processor. If a depends on the amount of lost data that is accep difference is detected that is greater than pre table, the number of disruptions to the system determined tolerance limits, a determination is that are acceptable, and whether the cost can be made about which computer is at fault. The justified. A third restart method is to generate failed computer is shut down, and the other uses an audit trail. An audit trail records all input the register contents and program pointers of messages, which allows the program to rerun from the failed processor to immediately continue the time of the last valid set of data (Champine, processing. Figure 2~3 depicts a typical 1978). hot-standby dual-processor· system. If the file~ of the primary processor are not The semiautomatic switchover configuration also available, the required software must be avail consists of two identical computers. The dif able from another source. The secondary proces ference is that the change from one to the other sor cannot begin operation from the exact point is not automatic, and therefore the secondary of failure, and the starting point must be computer is not required to operate in parallel manually entered. at all times. When the primary computer fails, the secondary computer must be manually switched In a cold standby system, the secondary computer into operation. If the secondary computer has may be engaged in a different application while access to the files of the primary computer, it the primary computer is in op~ration. If the can quickly begin operation at the same place. primary computer .fails, this secondary proces This is usually accomplished by using a shared sing must stop and its functions must be trans or switchable disk or by recording data on a ferred to a manual backup or remain uncompleted. transportable medium. One method is to have this disk contain all required files for normal 2.3.9.2 ~rolonged Downtime Reliability. The operation. A second method is to periodically second type of reliab111ty 1S the prevention of update the files of the secondary system with prolonged periods of downtime. Here, both the the status of the primary system. Between up MTBF and MTTR are of importance. The MTTR may dates, critical events are stored (checkpointed) be decreased by improving preventive mainte to the switchable or transportable medium. Upon nance, buying increased or guaranteed maintenance failure of the primary computer, the secondary service, programming automatic restarts, or 9 providing backup components. If the frequency remote maintenance computer. This link provides of failure increases, the length of acceptable access to special test routines, special dump repair time most likely will be shortened analyses, a data base of , system problems and' because of decreased user tolerance (Yourdon, solutions, and interactive diagnostics by 1972). factory experts (Champine, 1978). 2.3.9.3 Protection of Data. The third type of 2.4 SOFTWARE reliability, protection of the data base, is becoming increasingly important as more users Software is the collection of instructions given have access to common data bases. Three methods to a computer to direct it to produce desired can be used to increase the reliability of the results. Covered in this discussion 'of software data base (Yourdon, 1972). At fixed intervals, are operating systems, language processors, li periodic copies of files may be made on a second, braries and utilities, data management, applica more reliable medium such as magnetic tape. In tion software, reliability and maintenance, and case of a failure, files can be restarted at the documentation. point of the last "dump" (copy to tape). Whereas hardware costs have been declining each An audit trail may be kept, recording all trans year, the reverse has been true for software actions and retaining a copy of the affected data costs. Software is produced by skilled in base records. In ~ase of failure, any uncom dividuals whose salaries have steadily increased. pleted transactions are reprocessed using the In a new computer system, application software original data record (Yourdon, 1972). A combina may be ~O to 200% of the hardware and system tion of periodic dumps and audit trails is called software cost (Kenney, 1978). As costs increase, an incremental dump. In addition to periodic manufacturer-provided software becomes a greater dumps; copies are kept of all file changes since factor in total system price. the last dump. 2.4.1 Operating Systems The third method is to record data on two disks. This provides a check of data integrity and a Operating systems software controls the internal backup in case of failure. This method does not operation of the computer hardware and software prevent both data bases from being destroyed by systems. Operating systems have been developed application program errors, however~ to manage the increasingly complex assemblage of tasks that computers perform. They 'are designed System integrity is of equal importance to hard to allow easy user access to resources and to . ware reliability. Errors that generate question allocate those resources productively. able data must also be identified and corrected. To ensure integrity, error detection and correc First-generation computers allowed execution of tion or retry must be resident in main memory, one program at a time, and control of the com~ mass 'memory, and I/O and data path areas. puter was given to an operator or user. As hard ware capabilities increased, the percentage of 2.3.10 Maintenance time spent executing (processing) user jobs de creased. System resources were no longer used Reliability and availability requirements in efficiently because with one user, a large per crease with time because of users' demands for centage of time was spent in queuing, setting, better service. At the same time, the cost of and controlling jobs. In addition, resources maintenance to provide this level of service were not used efficiently because with I/O-bound also increases. Currently, the charge for a applications, the CPU remained ~dle during I/O typical maintenance agreement is 5 to 10% of the operations. original hardware cost per year (Cabet, 1979). To alleviate this misuse of CPU time, newer Manufacturers ar~ using several methods to operating systems allow the loading of multiple provide increased reliability while keeping, programs into the system. MUltiprogramming maintenance costs low. Repairs that can be permits a second program to use the CPU while completed on site save technician time and the primary program waits for its I/O return. travel. Redundant hardware allows the system to Currently, many processors operate at 1 million continue operations until the part can be to 10 million operations per second but must replaced. Main memories can ,be installed with access disk memories at 50 milliseconds. Conse an error-correcting code that "corrects all quently, these processors have the power to single-bit failures a~d identifies all double perform 100,000 to 500,000 operations during the bit errots. This helps the system to 'continue time of a file access (Flynn, 1979). operations until a iechnician atrives. Operating systems are designed to use the compu Built~in maintenance processors can automati ter itself to relieve the operator of control cally identify and log many errors. Often this functions and to provide multiprogramming. They allows operations personnel- to replace the provide a standardized structure with which users failed component. For more difficult problems can obtain access to the computer. Aithough requiring maintenance personnel, the maintenance standardization imposes some restrictions, it processor can provide quick, accurate diagnos allows much greater efficiency in the execution tics. Taken one step further, the diagnostic of processing jobs and frees the programmer from processor can be linked via telephone lines to a ,any computer operations responsibility (Sayers, 1971) • 10 2.4.1.1 Features of Operating Systems. In • I/O management subprogram--The I/O addition to providing for better use of system manager schedules and executes I/O resources, operating systems integrate features tasks. This subprogram must control the appearing in second-generation computers (Sayers, space on disks used for direct access, 1971). Relocatability allows storage of programs allocate the use of tape drives and in a location other than the beginning of main printers, provide a directory to memory. Thus, mUltiple programs can be loaded external memory, close and open files, in the computer at one time. A universally used and provide I/O error recovery. memory control program must reside in memory along with application programs. 2.4.1.3 Types of Operating Systems. Five general types of operatlng systems exist. A Reenterability allows a program to be executed a serial batch operating system schedules jobs second time before it is completed the first sequentially, processing only one at a time. time. This becomes important for multiprogram Multiprogramming operating systems allow many ming because multiple programs may have to jobs to run simuitaneouslY. The CPU does not execute the same part of the operating system execute each job simultaneously but divides CPU concurrently. and I/O operations, allowing one job to be executed in the CPU while others wait for I/O Interrupts are messages sent between programs returns. To the user, mUltiprogramming appears within a computer. They alert the control to be the same as serial batch processing be program that external servicing for a program cause he or she may have to wait for entry into (such as receiving input) has been completed and the system and once the job is completed output that the program is again waiting for CPU time. is returned all at one time (Sayers, 1971). Multiprogramming jobs may be submitted in Channels are small, independent processors that directly (off-line) using a card or tape reader handle only I/O operations, such as data transfer or directly (on-line) using a CRT display or and scheduling and queuing I/O requests. They teletype. allow the CPU to remain free for data processing. Interrupts from the channel signal completion of Time-sharing systems attempt' to give the user a particular job (Lister, 1975). the impression of exclusive use of a computer. Time-sharing users enter and receive data and A linkage editor/loader formats a program for instructions on-line using a CRT display/ execution and assigns addresses to the code in keyboard or teletype connected to the computer. reference to the program beginning. When a pro Because the speed of human typing is slow com gram is loaded into main internal memory, the pared with normal I/O or CPU processing, the linkage editor stores the location of the begin operating system can provide a response that the ning of the program. Any references to the user perceives as immediate. This fast response program are then made through the linkage editor, time allows interactive user-to-computer communi which can compute real locations by adding the cations. Time-sharing operating systems assign program's beginning location to the relative each program a percentage of the CPU time and address in the program. rotate programs in and out according to this schedule. 2.4.1.2 Subprograms. An operating system can be divided into the following three main Real-time operating systems usually run only one subprograms (Sayers, 1971): program. The program is usually input from one or more locations on a time-critical basis • Executive subprogram--The highest level (Lister, 1975). For real-time applications, of control, the executive subprogram even the delayed-time operation of a time controls the other functions of the sharing system is too slow. A typical real-time operating system. A program or operator application is classification yard control, communicates to the operating system which requires instantaneous entering and pro through the executive subprogram. cessing of car movement readings to determine car retardation and/or switch positioning. • Task/resource management subprogram--The task/resource management subprogram pro Virtual memory operating systems are the fifth vides for the control of the use of sys type of operating system. With multiprogram tem resources. System resources include ming and time-sharing, the CPU is used more main memory, CPU time, I/O operations, efficiently but great amounts of memory are and the system clock. These resources required. To extend the relatively expensive must be allocated among the currently main memory, virtual memory systems treat part waiting programs and the internal opera of disk storage as main memory. The main memory ting system tasks. Task management is divided into "pages," usually 500 to 1,000 includes execution timing and control, words long, that are brought (swapped) into main job queuing and scheduling, priority and memory when needed. interrupt recognition, and system error recovery. This subprogram also arranges 2.4.2 Programming-Language Processors programs in main memory, brings programs from mass memory, and feeds programs Programming languages were developed to provide into the CPU for execution. a method for directing the computer to perform tasks for the user. The most fundamental way is 11 to make a list of the machine instructions that HOLs are English- or mathematics-like so as to must be performed to accomplish the required be easily learned, easily programmed, easily task. Because no translation is needed, the CPU changed, and hardware independent. Because may execute the "code" directly. learning and writing HOL programs is easier, the lead' time is much shorter than for a comparable The early users of computers found machine program written in assembly language. Standards languages difficult to learn, tedious'to use, for HOL compilers ensure that applications pro difficult to change, and error prone (Couger & grams can be transferred to different hardware McFadden, 1975). To facilitate generation of and ensure that programmers can work on many computer instructi'ons, language processors were different computers without retraining. The developed. These programs use the computer to relative ease of debugging, modification, and translate a user-oriented source language documentation makes HOLs useful for programs program into machine-readable binary that are subject to frequent changes~ Therefore, instructions. using a language such as FORTRAN or COB'OL is usually desirable for complex control algorithms, 2.4.2.1 Low-Order Languages. Low-order or . inventory programs, and other non-I/O-dependent assembly languages are written to closely re tasks. semble machine instructions. Binary instructions are represented with mnemonic codes, and binary HOLs are usually not used for PC applications addresses are translated to simpler relative unless they are extended to include real-time addresses and represented by alphanumeric codes. control process instructions that' enable the program to interrogate external interrupts and Duri~g the assembly process, each source to interface directly with I/O devices and statement--normally comprising a label, a computer timers. mnemonic operation code, and an operand (or a variable)--is translated into its machine The complexity of HOL compilation (translation) language counterpart, typically in octal-coded requires additional machine time and memory binary form. Beca~?e of the one-to-one equi space and, because of the flexibility of the HOL valence between the assembly ianguage and the instructions, compiler~ may generate some in machine language, the programmer is offered the efficient codes. Despite these disadvantages, flexibility of taking advantage of machine lowered programming, processing, and memory hardware features--for example, bit-position costs make HOLs increasingly attractive to most manipulation, special logic instructions, and users. I/O and interrupt devices directly accessed by assembly programming. The assembly language Among the HOLs in general use today are (Couger also enables the programmer to economize in the ~ McFadden, 1975): use of execution and memory cycle time and to achieve a better control of memory space use. • Scientific use--FORTRAN, ALGOL, PL/l Compared with machine languages, low-order languages offer easier programming, efficient • Business--COBOL, RPG instruction use, and easier error correction (debugging), and they do not require that the • Time-sharing--llASIC, FORTRAN, PASCAL programmer keep track of absolute storage locations (Couger & McFadden, 1975). • List processing--LISP, SNOBOL Because they offer the user the ability to take • Simulation--SIMSCRIPT, GPSS. advantage of hardware characteristics, assembly languages are suitable for classification yard 2.4.2.3 MIS' Software Language. The software sensor data acquisition programs in which inter language chosen for use in a classification yard face with communication I/O channels is the rule MIS computer system should be well suited to rather than the exception. Assembly languages file acces~ing, file manipulation, and report are applicable to detec'tor scan programs, I/O and display generation. A large 'amount of interrupt routines, and switch and retarder scientific processing or mathematical computa control programs. tion is not necessary in management applications. Assembly languages are still far removed from In general, MIS applications ona large computer normal human logic and thought. Problems to be fit well with high-level business- and file solved must be broken down into small, detailed oriented languages, such as COBOL. Progr~ms increments. Coding and debugging are slow and written ,in an HOL are preferred because they are difficult; and because instructions are machine easier to develop and modify. Programs written dependent, programs in assembly languages are in a standard machine-independent language can not readily transferable to a different manu b~ transfeired to other machines and can take facturer's computer (Couger & Mcfadden, 1~75). advantage of software developed on' other machines. If a microprocessor is used for an 2.4.2.2 High-Order Languages. High-order application or as a communication processor, a languages (HOL) are oriented toward users' lower level language may be better. Because of problems rather than toward machine hardware the smaller memory and processing power, micro characteristics. One statement in an HOL may be processors benefit from the efficiency of equivalent to 10 to 20 assembly or machine assembly languages. language instructions (Couger & McFadden, 1975). 12 2.4.3 Libraries and utilities A user can add, write, change, and delete files within his or her own directory. When files Many computers and operating systems are de external to the user are created, they are con livered with a set of independent programs and trolled by the file creator. In most file man routines designed to be of general use to most agement systems, the control of file reading, users. Data-handling utilities provide user writing, and deletion can be restricted to the callable control of printers, CRT terminals, user, specified others, a group, or any user, as tape drives, and other peripherals. These determined by the file creator. A file manage routines allow formatting of output, device ment system will usually allow multiple users to to-device data conversion and transfer, and read a f~le simultaneously but will allow only listing of directories, tables, memory ad one user at a time to write to a file (Sayers, dresses, and the like. 1971:). Sort/merge utilities are packaged routines that Backup files ,are often a~tomatically created to provide for the efficient sorting and merging of allow recovery if a system failure occurs when a files. Sorting routines take strings of unor file is open. Backup files may be checkpoint dered records and sequence them according to files, transaction data files, or previous ver user-specific keys such as control fields; cus sions or editions (Sayer~, 1971). tomer name, part number, and record number; ascending or descending order; and record size. 2.4.4.2 Data Hase Management Systems. Data Merge routine's take files and combine them in an base management systems (DBMSs) allow the ordered manner. creation of a more complex data structure and file organization. A data base has been defined Library routines provide an ordering method and as: locations for storing user-callable routines. Corrunon programs found in 1 ibr'aries inc lude: ••• a collection of interrelated data . mathematical functions', trigonometric functions, stored toiether with controlled data reduction routines, and regression analyses. redundancy to serve one or more The library maintenance program allows users to applications in an optimal ,fashion; add their own routines and programs to the the data are stored so that they are library.' . independent of programs which use the data; and a corrunoh and controlled 2.4.4 Data Management approach is used in adding new data and modifying and retrieving existing ,A method of organizing, accessing, and updating data within the data base. (Martin, long-term on-line storage of data files is re 1976). quired for most computer systems. Disk files are needed that allow easy access by all users A DHMS is a set of programs and user-available and that eliminate the need to reenter of ten routines or corrunands that create and maintain a used data and programs via slower speed tape data base, retrieve data, and produce output drives, card readers, and CRT terminals (Lister, data. Data base creation and maintenance entail 1975). file structuring, input transaction processing, logical and interactive maintenance, and file 2.4.4.1 File Management Systems. File manage- reorganization (Sayers, 1971). The simplest file ment systems are designed to create and delete structure is a sequential one. Records in the files, locate and access on- and off-line,files, file are not stored in any order, and the user allow file references by address-independent searches for a particular record' by sequentially symbolic names, permit and restrict the sharing passing through the file. of files, and protect and/or restore files in case of computer failure (Sayers, 1971). Files In a hierarchical file, the file structure re may be accessed by sequentially searching each sembles a family tree, with each record (parent) file for a label comparison, but most file man pointing to a number of lower level records agement systems use a mapping technique. Direc (children). Each child in return may act as a tories contain a ~ist of symbolic file names and parent to lower level records. If a structure their physical addresses in ma'ss memory. is defined such that a child may have more than one parent, the structure is called a network or In many file management systems, a mul~iple plex structure. level or hierarchy of directories is used (Lister, 1975). In a three-level hierarchy, a An indexed structure reserves a portion of the master file directory contains a pointer to each file for storing keys that index information in user file directory. Each user directory con the main body of the file. In a list structure, tains a list of user internal directories ,that each record contains a pointer to the address of in tu'rn contain a list of file names and their the next successive record. If the last record physical addresses. A complete file name con of the list points to the top of the list, this tains a part symbolic of its location in each is a cycle or ring structure (Sayers, 1971). directory level. For example, the file name CHAP.2 indire,ctory HOOK of user SMYTH could be A relational data base uses a simpler method of referred to as SMYTH BOOK CHAP.2. In addition, logically representing hierarchical data a file name may also contain a reference to its structures. .Pointers to multiple records are edition, for example, CHAP.2 and CHAP.2 OLD. eliminated. To link children to parents, the 13 identifying field of the record is a combination accounting, and other programs. Smaller and of the identifying fields of the parent and first-time users cannot afford the considerable child (Martin, 1976). software investment needed to use relatively inexpensive hardware. Software packages can be These file structures refer to the file organiza purchased as is or customized for the user, or tion of the data base, not to the structure of turnkey systems can be obtained. Turnkey ven user-accessible files of the file management dors provide a complete computer system including system. hardware, system and application software, in stallation, testing, documentation, and training. The input transaction processing of a DBMS en ables the user to define input formats, validate The lower costs of applications packages are input elements, convert data to internal fo~nats, offset by s·ome disadvantages, some of which are and then store the data in the file. Verifica the following (Kenney, 1978): tion,methods include range verification, internal comparison, and input sequence checking. Logical • Standardized or modified packages may maintenance provides for preprogrammed file main not fit a user's operations. tenance, .and interactive maintenance allows file manipulation from an on-line te~inal. File • Software is available for only a limited reorganization routines pe~it the reorganiza number of applications. tion, merging, and restructuring of files in preparation for data output (Sayers, 1971). • Once packaged software is purchased, the user must depend on its supplier for Data retrieval {s an important aspect of DBMSs. modifications and upgrades. Simple query languages provide flexibility to control the data retrieval •. Instructions usually • Packaged software can not be easily consist of a data base field, a logical operator changed. such as "equal to," "greater than," or "less than," and an operand. The operand may be a con 2.4.6 Software Reliability and Maintenance stant, another data field, the result of a nested instruction, or an arithmetic instruction. In Software reliability .can be determined only after structions may be connected using logical con a program is in use. Its reliability can be junctions such as "and," "or," and "not" (Sayers, measured by taking the number and degree of 1971) • errors found and by rating user satisfaction. Neither the numeric nor subjective method is Queries may search single files, mUltip1e files, adequate, however. or chain to secondary files based on results of the first file search. Queries may be made in a As with hardware, software has a high failure batch or interactive mode. rate in early life and again as it ages. Early. programming errors are found and repaired as the In addition to standard requests, such as for program is first developed and tested. Later, directory listings and input transaction the software "fails" because it is obsolete, listings, user-formatted reports may be produced outmoded by newer software techniques, new using instructions similar to those used for hardware requirements, and a changed applica data retrieval. The user may be required to tions environment. write a program to produce the required program generator. Functions controlled by report pro Software errors are eliminated during software grams include labeling, data formatting, and development by running the program in different top-of-form control (Sayers, 1971). test environments. With each test, the more obvious errors are found but soon diminishing 2.4.5 Application'Software returns require higher cost tests to locate the remaining errors. Programs designed to operate The second major software grouping is application in a limited environment can be tested easily software. Whereas systems software is concerned under most expected conditions and therefore with the internal operations of the computer have a very high degree of reliability. The system, application software ·refers to programs ·programs that must operate in mUltiple environ for activities external to computer operations ments or in a very general environment cannot be and specific to jobs accomplished by the com tested for all error possibilities. The reli puter system. ability of general programs, such as systems software, therefore is lower. In the past, many users used their own program ming staff to develop application software. An Typ~cally, a finished software product has one internal programming group was responsible for error per 100 lines of program and 1,000 errors designing, developing, supporting, modifying, per system software release. Of these errors, and upgrading all software specific to one site. estimates are that half are not programming As computers have become less expensive and thus errors but are errors in understanding the appli available to more and more users, applications cations requirements (Champine, 1978). software packages have been developed. Software packages are standardized and tailored to the The production of software remains an art. growing number of organizations needing DBMS, Little has been accomplished to improve develop retail sales, inventory, manufacturing, payroll, ment methods, production control, or quality 14 control. Some of the methods used to improve • Easy update, retrieval, and control of a software reliability and programmer productivity centralized data base. are use of programmer teams, structured program ming, top-down design, and design review walk • Coordinated system and ~oftware throughs, development. The hardware vendor usually provides and main • Large, well-rounded central staff with tains the system software. Software is licensed greater depth of abilities. to the user at a one-time cost and maintenance is usually provided at no charge for a specified • No redundant data files; maximum use of period. After that time, a user may buy con- storage. t inued software support. This may inc lude the correction of software problems and provision of Despi te these advantages, large ,cen tra 1 computers future releases of updated compilers and updated are a problem to some organizations. With a operating systems. If a user does not have the single computer system, if anyone link in the most recent software, problems may occur when system fails without a backup, the whole system support is needed. fails. As centralized systems grow, more com ponents are involved, thereby increasing failure Applications packages also carry a guarantee of rates. a specific duration~ After that period, however, obtaining software support may be difficult. If If an organization is growing, ~he entire central the user has made any modifications to the pro system must be replaced periodically by a larger gram, the vendor can later argue that the origin system. Because of their size, ,centralized of the errors is uncertain. systems can only be enlarged in very large and expensive increments. The difficulties of moving 2.4.7 Software Documentation all application software and peripherals to a new system can be considerable (Scherr, 1978). Software documentation provides an explanation of software design that can be invaluable when Moreover, in many organizations" centralized changes'must be made in the future, especially data processing does not correspond with the when the original programmers are no l-onger management style. Decentralized management available. Documentation comprises both com practices require more local control of resour ments within the program and separate documents. ces and an accounting system focused on regional and divisional profit centers (Champine, 1977). Documentation should include an overall func Centralized computer operations do not fit well tional design of the system, specifications for in this management approach because the central data files and formats" input and output formats, facility usually falls outside the ~ormal corpor and a detailed description of each mO,dule of the ate organization. High overhead costs and low program and how it interacts with other parts of responsiveness to line managers have plagued the program (Martin, 1965). Software documenta many companies (Scherr, 1978). 'For many organi tion should be a basic reference instructing the zations, centralization results in a detrimental user in how to use the software. complexity of scale (Becker, 1978). 2.5 NETWORK ORGANIZATION 2.5.2 Decentralization 2.5.1 Centralization A popular trend in recent years has been decen tralization of computer resources because the Typically, the high cost of computers has forced traditional hardware economies of scale are no the centralization of computing resources to longer being realized. Processing and storage take advantage of the economies of scale of a performance-to-cost ratios are 10 times those of centralized facility provides. In a centralized 10 years ago (Kenney, 1978). During the same computer system, processing and data storage are time, however, communications cqsts have de at one central location. Among the many advan creased at only half that rate (Champine, 1977; tages ,of having centralized data processing and Scherr, 1978). For organizations with many geo storage are (Champine, 1977; Kenney, 1978): graphically dispersed users, communication to these remote sites has become a major cost • Economies of scale in. hardware, consideration. Some organizations have found programming, and operations cost. that decentralized processing can be cost effective' in reducing communications require • Demand smoothing. ments (Champine, 1977). • Centralized implementation. For organizations where computer availability is important, decentralized processing can provide • Unified control, coordination, cost better reliability. The design and effectiveness accounting, and security. of a distributed processing system depend on a proper distribution of data. If most critical '. Hardware/software compatibility. or often-accessed data are site specific, they 15 can usually be physically distributed among Three situations can be regarded as typifying independent processing sites. distributed processing (Champine, 1977): Some advantages resulting from a distribution of (1) Large volumes of input and data computing resources between remote sites are: accessing transactions occur at geographically distributed points. • The system remains available through Fast response times are needed. central system failure and need not Communication to the central or other totally rely on data communications sites is infrequent and of low volume. hardware. (2) Large volumes of data are generated at • Complexity of scale is reduced by a central location. Data can be distributing processing and files to changed either centrally o~ at o~e ~f remote sites. many remote sites. Quick access to the information is required. • Better price/performance for some I specialized applications is realized (3) Remote locations generate and maintain because of reduced overhead. their own large data sets. These remote data bases must be quickly • Application development, implementation, accessible for inquiry and change. and expansion are independent. The need for one node to require information of another is infrequent. • Interactive response time is better. In a decentralized organization, the cost of • Greater control and involvement of users growth is site specific. Thus, the cost need are possible. not be carried as overhead by all the users. The decision to have some distributed processing • It permits decentralization of functions need not limit the design to distributed proces in a structure parallel to a company's sing, however. A combination of processing management organization but maintains structures may best fit the organizational central control. structure and management policies. • Growth and upgrades can occur in much 2.5.3 Functional Distribution smaller physical and cost increments. A simple centralized processing system can be • Informatio~ is accessible both centrally viewed as an I/O module communicating through an and locally in efficient site-specific operating system to an application program and file structures. Independent failures processor. The application program and processor do not affect data base access, and the in turn communicate through an operating system communications volume is reduced. to a data storage module. This simple system can be divided for distribution at three dif Disadvantages of decentralized systems include: ferent points (Scherr, 1978): • Hardware, software, and personnel may be (1) Between the I/O module and the duplicated. application program. • Control of system development, (2) ~etween the application program and standards, and expense is difficult. the data storage module. • With an increased number of components (3) Within the application program. in a fragmented system, more failures as a whole may occur. If the system is split between the I/O module and program, the independent processor is called • Efficiencies of distributed processing a front-end processor. This type of processor are lost when multiple 'sj.tes often exclusively handles I/O processing, such as code access the same data. conversion, message queuing, polling of remote terminals, and error recovery (Couger & McFadden, • If the data are replicated at different 1975) •. This split provides an efficient distri points to speed accessing, maintaining bution of processing when the I/O load is great. the accuracy of all sets of data is Examples are a network of terminals and terminals difficult. requiring a significant amount of screen format ting (Scherr, 1978). • Development and training are difficult. When processing is split between the data storage • Hardware maintenance is costly. module and the program, a back-end processor is created. Such a split provides a central access • Security tisks are increased. monitor for single or mUltiple ~torage devices. 16 A back-end processor can also be used as an (McGlynn. 1978). An example would be the geo independent data base processor. graphic distribution of similar tasks. such as accounting. entered and processed at the regional In the third division (a centralized computer headquarters of a nationwide organization. system within the application program). the structure of the application program determines A vertical or hierarchical distribution is how and whether the processing can be completed created when processing is split into mUltiple at different nodes. If processing can be split components of differing sizes and functions. and into tasks of equal importance and similar func a rigid multilevel master-to-slave structure is tion. the distribution is termed "horizontal" created (McGlynn. 1978). 17. CHAPTER 3: OPERATIONS AND FUNCTIONS OF THE YARD INVENTORY SYSTEM This chapter discusses. the gathering. processing. • Fast, efficient reporting and retrieval storage. transmission. and retrieval of inventory of infonnation using CRT tenninals and information in classification yards. A descrip direct links to other computers. tion of railroad operations is presented first. and then the computer functions are described. • Increased inventory control by giving respective departments complete inven 3.1 RAILROAD OPERATIONAL DESCRIPTION tory maintenance responsibility. As a railcar moves through the classification • Reduced manpower needs by reducing and yard. information on the car is updated to re eliminating manual tasks. flect its present position and status so that an accurate and up-to-date inventory can be main A track-standing inventory is usually kept for tained. receiving, classification, and departure tracks. The inventory includes the cars on each track and 3.1.1 Manual PICL their order on the track as well as the minimum car information. A semi-track-standing inventory Two major types of yard inventory systems are keeps a record of the cars in each track but not used to monitor car location and track status Ln their order; an MIS computer keeps only this the yard: manual and computer inventory systems. level of inventory detail. Unless more detailed In the manual PICL (perpetual-inventory and car records of car position are kept as part of a location) system, punched ~ards are produced rep yard inventory subsystem, this subsystem can be resenting each car. A rack of pigeonholes is part of either the MIS or PC system. Exhibit 3-1 used to represent each track in the yard. The is an inventory of arriving cars and cars in the yard office clerk manually sorts the waybills and receiving classification. and departure yards by punched cards by referring to the switch list. block number in Santa Fe's Barstow Yard. Within The selected pigeonhole corresponds to the track each area of the classification yard. information on which the individual car was switched. In is kept on that area's operations. this system, the physical track-to-track car movement is followed by moving the waybills and The rest of this discussion is structured accord punched cards from pigeonhole to pigeonhole. ing to the movement of cars through each area. Yard personnel can determine the cars on any track by looking at the punched cards in the 3.1.3 Receiving Yard corresponding pigeonhole. This manual system LS also referred to as a card-PICL system. Before a car arrives in the classification yard, an advance consist of the arriving train is A manual PICL system should provide centralized transmitted from the previous yard or the rail and current information on the location of cars. road's central office by telephone, teletype, or Unfortunately, centralization requires consider a computer data link. The data received are able communication between personnel requiring stored in a "train-due file." The advance the information. Providing current information consist contains the car ID number and lading, is difficult because of the use of antiquated origin, destination, and routing infonnation. data processing equipment, the difficulty of This infonnation stays in MIS files throughout maintaining the card inventory, difficulties in the car's stay in the classification yard and is infonnation reporting and retrieval, and the de included in the outbound consist when the car lays in providing switch lists at remote loca leaves the yard. tions. Human errors also frequently hamper the system. In addition to individual data on the car, the advance consist may provide the train ID number; 3.1.2 Disk-PICL the number of loaded and empty cars; tons car ried; length of the train; lead unit number, An alternative is the use of a disk-based com total units, and helper units; and estimated puter inventory system. The physical movement time of arrival. After receiving the advance of cars is paralleled by the movement of car consist. the yardmaster may assign the receiving records among computer files. Instant and direct track and the route through the yard. Once a access to these files is possible via computer track is assigned, the receiving yard display terminals located at sites throughout the yard. indicates that the track is reserved. Among the advantages· of the disk-PICLs are: When the train arrives, ID numbers are recorded • Faster and more efficient data storage using videotape, audiotape, automatic car iden and inventory processing. tification (ACI) scanners, or pencil and paper. j I I Preceding page blank I 19 L ______------.-~ EXHIBIT 3-1 SAMPLE CAR INVENTORY BY BLOCK NUMBER BLCCI!. VOLUME 79338-1349 BLOCK /I DESC DUE R-Tn B-YD D-YD o rHER TOTAL 1 -il/ATCARS 5 11 13 13 7 49 2 BOWL 'IRK 02 21 2 24 1 95 123 e GLENULE IZ 18 6 ~1 2 ::7 7 BAlIS TOW (ilOLDS 50 MISe) 27 87 66 .3 H1 58' 9 MODESTO-EMPIKE JCT 8 22 26 52 2 110 U BAKERSFIELD 50 AaEA GT10 1 14 15 64 3 97 11 PHOENIX GT11 1 e 17 34 e 60 12 BORON LOCAL GT12 e 9 e 11 2E 13 ALBQ WINSLO~ So EAST 0 15 13 ~ "1 29 14 CALIA So AREA GT14 3 17 14 31 4 69 15 CLOVIS 0 5 95 1 59 170 19 HOBART 14 18 '2 71 2 11:17 20 BARS'IOW UP 7 7 21 e 2 37- 21 RICHMOND AR!:A So TOFe 16 50 33 17 4 120 22 KANS AS CITY & BEYOND 13 57 52 42 2 160 24 S'IOCnO~HIP 3 14 27 1 e 45 25 STOCKTON-IIPBN 1 5 12 1 <1 25 26 HARBOR SHORTS GT26 15 24 14 41 5 9& 29 TORRANCE 2 14 1.3_ 26 1 54 30 SAN tiEGO 50 ARiA 2 11 4 1 48 6b 32 STOCKTON 50 ARBA 50SP 5 6 14 .31 ~ 56 34 SLSF TULSA G':'38 e 5 2 -z I:j 7 35 ~RD £IS'IRICT SHORTS GT35 0 12 14 21 41 BE 36 1ST £IST SROdTS GT3 0 5 2 l 11 16 37 PICO HI V};j(A 41 .3 20 1 71 36 SLS2 ~E~F~IS&BEYOND GT38 1 19- 11 0 e 31 39 '!AISER So 2ND ~ISTS dTS 5 15 8 1 33 62 41 SAN EERNARDINO GT41 4 -3 1 1 30 44 42 PARKER LOCAL saORTS GT42 0 15 3 12 e 3rt 44 SA~TA ANA e 4 '2 11 15 33 46 SNurR asp GT16 4 0 1 9 2 16 49 MOJAVE DIST SHORTS ~ 6 2 e ol E: 51 BARSfOW STGE YARD 0 e 4 e 45 49 52 BARSTOW TO SALTuS S~ORTS GT33 0 2 Ii' 2 4 55 ALEQ So NS DIS! SdORTS G!,3~ e 3" 2 2 21 26 57 ABILENE SET OUT GU6 e e 0 4 0 4 5F FCRT .. ORTH GT16 2 3 1 7 1 18 5S NEW ORLEANS GT15 0 e e 3 Ie 3 60 BROIIN,*OOD G1'33 2 2 4 26 I<: 4~- 61 ilOUSTON. II 3:3 0 2 5 0 7 62 LUBBO:K Gr33 0 e "Ii) 1 k!- 1 - 63 DALLAS GT3~ 1 2 0 1 'l ~ 13 64 FORT -iORrH G£3:3 .3 3 17 e 26 E6 FULLERTON ORA~GE AilEA Z 4 2- 18 1 25 67 FULLERTON ORHGE AREA "1 3 7 16 rt 27 6E: FULLERTON OilANGE Ai!r;~ e e 2 5 ;:: E EP FULLERTON ORANGE AREA e 10 1 6 ~ 17 ?l BELE~ G1'23 4 ~ 0 ;) 8 72 AMARILLC G123 Ii:" 2 4 e 6 n EMPORIA GT23 e 2 e "4 ~ 14 74 wELLINGTON GT23 0 e 1 4 ~ ~ 75 KIOWA G'I23 III e 4 1e 1 15 77 LA~I RADA 7 S ? :57 I<; 6e E1 ALBUQuERQUE IZ 15 5 Z 21 82 TRINIDAD CS Ii) i:: 7 e I:l" 7 83 PUEBLC So BEYOND 0 9 '2 e -Il 16 84 LAJUNTA 0 1 'l ~ 1 S0 VALLEY PARK MO - 22905LS; e "7 e 12 7 91 OCEANSIDE e 3 2" il 7 12 S9 "'UNASSIGNED'" Z 0 1 5 .. 6 H1 BARSTOW NEW YARDS ~ 11 0 1e 21 109 "'UNASSIGI'>ED'" 25 2E 11" 39 4 te7 115 ANTIOCR IZ 1 e. 2 11 116 PITTSBURG 2 IZ 1 ~ ";a 6 119 LOSA~GELES SP 1Z 12 19 41 125 "'INVALID STAtION NUMBER'" Z 1 "6 2 6"" 78 TOTAL 226 6"" 54~ 7S1 944 304~ Courtesy of Barstow Yard, The Atchison, Topeka and Santa Fe Railway Company_ 20 This information is.checked against the inven each car throughout its stay in the yard (Allman, tory of the arriving train. Corrections to the 1968). Given the receiving track to be pulled inventory are made, and arrival time and track and the track assignment of each block, a list location are'~dded to each car's record. In of track destinations for each car is made. In dividual car inventory records 'are then created Southern Pacific' s \~est Colton Yard, the terminal in the inventory file. If the arriving train control computer (TCC, a yard MIS computer) auto originated locally, the yardmas ter will not have matically sends the crest control computer (CCC, received an advance consist. In this case, yard a PC computer) the switch list when requested. clerks must enter car information manually when The CCC then controls all switching and retarding reviewing car ID numbers and when preparing the automatically. In Southern's Inman Yard, the waybill from bill of lading information. An engine foreman uses a printed switch list to expected completion time for prehump activities manually switch cuts. (A cut is one or more may also be noted. consecutive car; going to the same classifica tion track. A cut list designates the order of The car location is updated in the inventory cars to be humped and how they are to be grouped wi th each movement of the car thro'ugh the yard. as cuts.) Waybills, bills of lading, and other paperwork are given to the yard or arrivals office clerk. 3.1.4 Classification Track The status, of each newly arrived car changes on completion of mechanical and inspection work, A car's location in the classification yard is the completion of incoming paperwork, and the changed in the inventory according to the switch generation of the switch list. list. The inventory change can be made in real time (as the car is humped) via the PC computer, A switch list is a list of the cars to be humped, or the change can be posted from the completed in track-standing order, that designates classi switch list. Any misswitched cars must be de fication track destination. Switch list is also tected and the inventory adjusted. A sophis used as a general term for cut slip, hump lLst, ticated PC computer may measure the weight and and classification guide, which may have more length of a vehicle and each track's distance specific definitions in some classification to-couple measurement and add this information yards. Switch lists may be generated manually to the inventory record. by the yardmaster or automatically by the MIS computer; Exhibit 3-2 is a sample of a computer Misswitched cars may be detected by visual in generated switch list. A classification number spection or by the PC computer. Another method or block number is assigned to and remains with is to count with wheel detectors the number of cars entering and leaving classification tracks. EXHIBIT 3-2 SAMPLE COMPUTER-GENERATED SWITCH LIST SW ITCH LI 8T I JOB-IO CURT TIME' 01: 41 PM YARD I TRACK DIRECTION S LF.NGTH 650 CIJT-JD SEQ INITNUM[ YATS002500 1.1) DUPO 10 RF.ER X 314 '28 SSW NUTROCK OsNL27 SSW 2 YIITS002600 loB DUPO 10 BFFR >: ::l44 78 SSW Nt JTROCK OsNL27 SSW 2 3 YATS002"100 LV mwn 10 BF.ER X 314 '28 SSW NUTROCK OSNL27 SSW 3 4 YAT8002800 LD DUPO 10 BFER Yo 344 78 SSW NloITF1ClCK OSNL27 SSW 4 5 RICHOOIOOO cr1 ,,9? eM 110 5 6 QWEROOOOOI ED KC~lO 8 6 7 R I CHO(lOO.~2 CM 999 7 8 F'T 201180 1..1-' CM 999 r.FIOTFX :9 9 LN 02:,972 E8 DA2 999 ?? F.VANSVIl.L 9 10 RICH014000 eM ':",9 eM 10 11 RICH0210(lO cr'1 99', CM II 12 RICfl013000 cr·! 999 eM 12 13 YATS005800 EN Hr. 10 MXOOI HG NW AOT 13 END OF LIST CoUrtesv of Missouri Pacific Railroad 21 When the physical inventory count differs from compiled by the yardmaster manually or with the expected count, the inventory is adjusted. computer assistance. As each classification of The inventory system must also keep track of cars is pulled from the classification tracks, individual exceptions that occur at the hump. , inventory tecords are upda'ted manually or through Examples include (Graziani, 1977): the MIS computer. Cars are grouped in inventory according to their train number and scheduled • Overweight cars departure time. Because each car record contains a weight figure, a total weight for the train can • Side-shift cars be calculated to estimate the number of engines needed. Car IDs and waybills are compared with • Bad-order cars the outbound consist, and the train is mechani cally readied. The outbound consist is sent by • Hold cars telephone, teletype, or a computer data link to the next yard or to a central-office or system • Rehump cars. wide MIS computer; it then becomes an advance inbound consist. Inventory is not exclusively an MIS application: A parallel inventory may be kept in the PC com The MIS computer of a classification yard can puter for redundancy. The PC computer usually also be used in the preparation of outbound stores only the receiving yard inventory or an trains. Such a system requires that the number inventory of the four or five cuts waiting to be of outbound trains be entered into the computer. humped and the cuts just humped that have not Using inventory destination information, the been updated in the MIS inventory. computer can display the cars that are appro priate for a particular train. Each car is Changes in cars' locations on classification displayed with its location, destination block tracks are usually posted to inventory from the code, loaded or empty status, weight, length, completed work order or switch list. and special handling requirements (McClellan, 1977) • 3.1.5 Industry Tracks Canadian Pacific's yard MIS system (YARDS) The inventory system of a classification yard presents a yard scan track map on a CRT screen may also be used to monitor cars on industry to display car locations in the yard. The "map" tracks in the area. This inventory includes gives the track number and total number of cars information on the location of the cars, their for each track and displays a single-character loading/unloading status, the shipper's name, outbound train code in the location of each and the date and time of arrival. A bulk inven car. An example is as follows: tory is kept for industry tracks. The location of cars is kept only by geographic areas, because Track Car only a small number of cars are at specific No. Total Train Codes sites. The MIS computer can use this informa tion to compute length of stay for demurrage 14 11 PPLE ••• E31.466 charges and alert the railroad of extended 15 15 22K33 ••• 466.7JJJ88 delays. This can be very important because demurrage charges do not cover wasted car The yard scan given can be the actual or pro utilization (Sargent, 1974). jected map after switching. The tonnage report of Potomac Yard (RF&P) displays the total number 3.1.6 Repair Tracks and Yard Vehicles and weight of cars on each track of a departing train (Exhibit 3-3). The yard inventory system can be used to monitor cars in repair yards and permanent yard vehicles such as switch engines. The inventory of repair tracks, engine tracks, and work equipment tracks EXHIBIT 3-3 SAMPLE TONNAGE REPORT is usually a semi-track-standing inventory. T!"j If a car is found to be damaged when it is in O-HER T~~A It'! :~;'y't'1BOU;:: llJ'? spected in the receiving yard, the switch list i=1j:'"Tt::R TRACk 1 Rl,16 is changed automatically or manually at humping 5 r?ECUU=!R ::::3 CARS It-l TRACI'( :=:? :?11J TON:3 so that it can reflect the car's location on a fA- r?ECUI_.AR :~: 1 CAR3 m TRACI< :=: 1. :::::31-3 Tort3 bad-order track or in the repair yard. 7 [;::ECU'-.AR :::6 CARS It~ TRACk :~6 :35-5 TONS TPRII"l 109 :~4 TOTAI_ CAR:::: n'?5 TOTR,- TOI'~S The inventory of yard vehicles need not accur O-lTI::R RmUEST ately reflect their current location because Courtesy of Potomac Yard; Richmond, Fredericksburg, end Potomac Railway Company, they are continuously being moved. Nonetheless, it is important to know of any out-of-service vehicles and to store information regarding the scheduling of preventive maintenance. The MIS computer can also be used to select the 3.1.7 Departure Yards best departure track and makeup engine (Petracek et al., 1976). By adding the weight of all the Outbound trains are assembled in the departure assigned cars and comparing it with the power of yard according to a makeup list, which is 22 the assigne~ cars and available engines, an optimal solution c~n be found. Taken one step further, the computer can be used to issue crew assignments and 'track makeup instructions. EXHIBIT 3-4 SAMPLE FOUR-HOUR REPORT. 3.1. 8 Informati"on'Retrieval H1P F!ll_If;;1 HClUP F:r:::Pt]PT TO OCSJI. ;~;=:3 I;:'1E,/11·---:30 In addition to keeping an inventory by ID number, AI'"H:I'" TPACk: :? 120 1 1"1-.'6 advanced disk-preLs can provide other inventory T~: IJ_A:3'3II'"ICATION '-':flUS MT'i:3 CAP:3 ',' I,JA:3HII"iGTOtl :3 C' ':> information, including: ~,. OA" 131_AND l'~ ',: t6 .~t::. C:PO~" • Number of misswitched cars. • Number of damaged incoming cars and shop reports (Exhibit 3-13). In a second type of management evaluation report, operational statistics and standards are • Summaries of work completed, car used to evaluate the efficiency of the yard. movements, engine movements. Examples include: • Summaries of car location by track and • Track utilization. yard. 23 EXHIBIT 3-5 SAMPLE TRACK INVENTORY INQUIRY .... -. ,::-~ - i::nTEP TRACI< THEt·i EnTER :::: F·OR ~:;OI'TH n F"OR NORTH J'~I::: i::n:"'Tt:p T~~ACK 1. r.:'l·~b TRACK J9 SC'.THBOUND CLASS YARD !:. !...... ClAn:: 5 t:t-1PTIES 11 CARS E.?1 TOI'-18 F' Cr.:: I HIT nUt·mER OT AT 1 RFP 3113 t: 29 J9 '··1T\· DRI)INDUST 2 RF"F' J147 E 39 39 1··1T\· DRI) I !'rDOST .::.r=:""7--:. I ~-'-_II :?: >IL.J 567613 - :~~9 CIGAR!:: P.JREYTOBA ,_: Il !'··II.·J 1-.:It:.---...-.... (t:. 1- :3'3 CleAR!:: P.JRTOBC .-...-. :5 0::J:""J=~ ;~4313 E ~:. ..:- J:: 1··~pT 'r' .-.,-, 6 i;::FP ;~~417 E .:.. ..:. [t'lPTV .-...... :;:FP ;::447 t: I::'.'::, O·lPT'r' ;::: :::Cl'J L :~:'~ 1::P lCV POT'..JAI....BPI 95'31 'j ':::OU I.... ::~I? . F.~P ICI-::· POTI.)P,t BR I '35'31 liJ '::OU I...... :3'3 F.:R ICI< POTl)AtBRI 9591 11 '::;OU 530:::'39 1- 3'3 BRlCI·( POTI)At BP. I '~5'~1 FNTFP ~'F"I~)IIP=:T Courtesy of Potomac Yard; Richmond, Fredericksburg, and Potomac Railway Company. EXHIBIT 3-6 SAMPLE TRACK INQUIRY REPORT TRACK JNQIJIRY TR~CK YiIR[1 1 I..H.:1l:"D ::::-N OJ: 41 P~l t~:;-OCT-19 TOT CARS: 13 Lo~ns. :; f'-t1PfIE~3. :::J CAR FT: 68~·:i TONS: Tm~ FT. :;:: 1:3:3 SHHUS: ! SW ITCH I r ST ( S) SEQ INITNUMBER LKNU Y8LK ~PCD CNTNT .N~Xl·vSYs.nESD tB-TRN l.f:1-U~ T1~N-ID IO-ID ST 1. 'mTS002500 L[I·'Il.! [IUPO BEFR >: :3'14 :?l" ~,SW 82~Ol osNL27 OSNL2701 ~~ YAT~::-:;002600 I_B4D Dl.IF'O BEF:R:< 34·'1, 28 s~~w 82607 OSNL27 OSNL2701 :3 YATS002700 L[l4U ntJPO BFTR X ~~'1'1. 7fl S~~W 82~Ol OSNL27 OSNL2701 'l YATS00280(1 1...l)4U DUf-'O BF.T:R;{ :3114 ;~8 :";~W 82607 OSNL27 OSNL2701 ~;*R I CH001 000 ct-l n·i 77011 01 6 QWEROOOOOl EU4U KCMO 72008 01 7 Rr.CHOOOO22 81314 01 8 PT 201180 I...B5H Ci1 BLGP~ {\nIl0~t1 62~08 01 9 I.. N 02:397~~ EB [11\2 '?'? RJrH79 82715 01 10*RICHOII1000 ell 01 22011 01 I 11 END OF LIST Courtesy of Missouri Pacific Railroad, 24 EXHIBIT 3-7 SAMPLE INDIVIDUAL CAR INQUIRY i."ll ~:;OU l'5;:~06 I ;--{i)At_ I"D tJ-HRV ENTER P(I)UEST 1'.11. ':;01..1 15;::~OI:,J SOU 1. ':);:'i:J63 II 11 i::IPR P)[ II i. 54 0 130 060::: 0:3 CU;~::;:::; I FIE D I NTERCHAt-iCI:: I] 1 ;~7 ~361-3::: PEPORTE:D ~;OU SOU CU;S:3IF rrD 0110 0611 eo 1__ F !j 4 5 I) 15 HOSE :35;~;::9'31 !'~ORL,j I CH Ot-i PA'r't'iUR ?;?4-:::;OU -POTYD-SOU -Btm:T -CI'~ -cn ::; 1 ::-:: 061)5 005544 01 '31;:: -BAR"1AC t--\C I RRUSA l5BE: ;~~;:::::a-] 06~]::: 0:3 ::H)P 16121~] 06~]':;& 04 J::TOA 1410 06H] 11 C-iT("~: f.;:EOUE:::;T Courtesy of Potomac Yard; Richmond, Fredericksburg, and Potomac Railway Company_ EXHIBIT 3-8 SAMPLE DANGEROUS CARS REPORT "[1::-:: 1)AHGf::POU::; C1=!~':=; U)CATETI I 1'1 HORTHHOUl'm CCAS3'r'APD I=iFTER TRACJ< 05 156 Ir-HT !---j Ut'H:: E P. OT AT UTU-:: 50040 D .--..:- .'-..:- T1ANCE:ROU:; --. --. RCF::-:: ;::4t,;~2 T: -, ,.') DAt-{GEROU:3 - --. UTU< '?E.'~~~1:3 TI ;~;3 '.-:- T1ANGEROU~3 n'1U-:: 1401:::: T.1 1 ;:: 1--'.':" DAt-iGEROU:3 1--:- 1--:- UTU< 7416;~ TI --' ' .. } IIANCEROU; ~ICF::-:: ::::~=:;~4~] T.1 14 14 DANCEROU3 .-..-. .':)':. CAr-=: 50::::01 TI '.-:":: ,_"- DAI'~CEROU:3 1 ...... I=iC:F::< 1.:3 ;1·4E. D '-1'., ..-:1.';" .':' ...'') DAl'iGEROUS f:U==~~:< ;~~:3::::45 Il :37 :~:7 '[n~t·~I:;EJ;:~']IJ~; nAH\: 5;::411 n 4:3 4:3 nAI'-IGEROU:; DA!'~CiEPOU:::; CAPS U)CATED I t-~ ::;OUTHHOUl'm C'-A~3:3'l!=lpn A!="Tffi TRACI< 0 1. pl.·.!6 I ('-~ I T nut'mER OT AT CAr-=: 44'314~] D :::: .--..:. DAt-~GEROU~3 1=ICD::-:: 9:::0:3 D '~ 11 DANCEROUS AeD:':: '366':;& D 11 11 DAI'iGI::ROU3 ceo:: 4171:::::3 D 1--:---' 1--:---' T1AI'~G(POU~3 l=u::F:,:: 14504 D 1--:---' 1--:---' DAI'~CEROUS I--~Ar>:: 173'3:3 D 1--:'"-' 1--:---' DANGEROUS nAT:':: 17::::'34 D 1--:---' 1--:---' DANGE:ROUS CAr-:: 4491'3 II 14- 14 DAI'~CEROUS UTU-:; ::::4::::6:3 n :3E. :36 DAt--ICEROUS '-:17 """" TGA::-:: 1.415;:: 1 D ._11 .:,...... i DANGEROUS ENTEP REOUI:::3T Courtesy of Potomac Yard; Richmond, Fredericksburg, and Potomac Railway Company_ 25 EXHIBIT 3-9 SAMPLE CAR INQUIRY YATS CAR INQUIRY l)I, q2 P~l !5-0CT-'l9 INIT NUMB I..fE KND TON FT CONT ;HH.NEXT;>SY3;>Df::ST;Hh. w;>DESTitINFr'J;,* YATS002500 L [l4U 69 ·~5 BEF.R ): 3Q4[1UPO 28 c;SW Nt TTROCK I\R YARD BL.OCK: DUPO TRiHN HI: OSNL27 TRAIN BLOCK: SSW CURRENT L.OCATION: IN YARD 1 ON TRACK 1 I\T 09: 1'1 Ml ! 1-0(",T-79 CAR STATUS: SWL \)1 SF.T-O--OSNI.2"J MV YO TRCK MOVMNT TIMF ;, [lATE JNB/OIJTBND TRMN TrMF [II\TE ARR YARD 01, 07: 00 AM 21,-AlJG-79 LAST UPDATE': 08: 20 1\~1 !?-OCr-79 YATS CAR INQUIRY 01,: 42 PM '!~-OCT-l:9 INIT NUMB L/E KND Tor~ FT CONT' *<>*NFJlT*SYS<>llESTlH.. .,. iH.. I1EST*INFO"'" YATS002600 L B4D 69 45 BEER X 844DUPO 28 SSW NUTRl1CK AR YARD BLOCV" DUPI1 TRIlIN HI' (>SNL27 ,TRAIN [~l'OC:~:,' SSW , CURRENT I..OC!HION:· IN Yr,RI) 1 ON lRIlrK 1 IH 09: 14 Ari ! t-I1CT'-l9 CAR STATUS, SWL 01 :~ET-O-(lSNL27 I'IV YO TRCK MOW1NT TIME &; DATE INB/OUTBND .TRAIN TIME DATE ARR YARn 01 0'7: 00 AM ?6-AuG-79 . LAST· UPDIHF~: Of:): 20 (.1M t2-8CT-79 YATS CAR INQUIRY 01: Q2 P~l !5-0CT-79 INIT NUMB L/E I END OF LIS! Courtesy of Missouri Pacific Railroad. EXHIBIT 3-10 SAMPLE REPORTOF TRAINS RECEIVED AND FORWARDED PIPrPT OF TR~INS ~E(EIV~D AND FOP~~R"Fn MC1NTH nF JL'NE 19~C RFrnVFD FPr!O rr~\oI~RDEI' Tr1 nATE RH '('IlJ CEO CP ~r" DtH TrTH CI'/'I'L PH .Cl rrr CP Hr n~H TrUt tVl''! 7 PIP 2~ 7 0 ' ~ ~ 3 7 3 7~?6 1 ~ il 3 ~ " ~~ ~ ~ 17 0 3D ~~ 3 7 3 5 1 2· ~ r . P 4 7 3 7" e 2 ~ 7 2 q 4 31 111 7 ~ c Z~ 110 p H ? 7~ 1~0 3 29 13e; f , 5 'f 3 o 24 11>4 7 20 159 7 I- 14 3 1 31 10;5 5 0; 3 27 1"" l\ 7 10 4 2 2Q 274 t, 7 ?3 20e; q 7 5 Z ~ 4 ? ~ . 249 7 7 10 ,? 2A 237 l~ 7 t '7 27f; , 7 4 2b 71'l3 11 o o o 0 o o r 27t> 1 C o I> 7t CI Courtesy of Potomac Yard; Richmond, Fredericksburg, and Potomac Railway Company. EXHIBIT 3-11 SAMPLE REPORT OF CARS HANDLED CARS HANDlFD ~ONTH OF I'AArH 19AO TOTAL CARS RECFIVED ANO FORWAAD(O SOUTHBOUND N 0 A T H 8 0 V N.D D AllY AVEIU(,E PECEIVED FORWAADE~ PECFIVED FORwARDED GPANn C AAS DATE DAILY CU~'l DAllY CUM'L DA II Y CU~' L DAILY CUP'l'L TOTAL CVI"L PER OAY 1 1181 11Rl 1237 1237 1130' 1130 979 979 4527 4527 452; 897 2078 740 1'177 709 183 0 71b Ib95 30~2 758'1, 3794 818 289b 885 281-2 1085 2924 72b Zlt21 3514 11103 :nOl e9,1 ~'893 1 al7 1,199 721 3b45 1034 3455 4089 15192 379~ "9 39"2 353 1,552 '0 3 b4 5 88 3543 490 15682 313f Courtesy of Potomac Yard; Richmond, Fredericksburg, and Potomac Railway Company. 26 EXHIBIT 3-12 SAMPLE REPORT OF DAILY INBOUND AND OUTBOUND TRAIN STATISTICS Rl:prRl OF r IP ~ t:> R f'lC r c:; S Fr' ~rR 24 Hr'lJ~S FNf'TNG 115Q PI'! 06/0Ql80 JNB[1\I~r TJl/TI'IS t r.~ns E"'~TIfS TOTAL IHP TtJn ~ 0 1 ? 12 RFP RrAO 7 "'17 144 5~6 ~ rt' RWY ~ 25P 51 30C; o:r J:I ~'Y Z 114 35 14Q rR RP f 270 32f- ~46 fH (' PR 4 84 ~7 171 on04 RP 1 33 t-7 100 TOT Al 7Fl 1101 72'- 1 PZ3 niT R N' ", 0 TI"HNS t OAr.S t=~f'TJFS TnT At IHP JNf" ') 1 i" ., ]I; RF~ p 06" 7 743 4('1q "52 S (1C I<~Y 'l ]1': 5 777 1.32 r.t("l p. ~:Y Z 137 t~ 203 CP PP '1 C' £JIb 274 pqO pr.r p~ ~ 134 t-,6 200 OEH pp 1 72 Zq 101 TOTAl 31 13~q 11?4 24Q3 r,PANn TOT Al ~q 2470 1e4f 4316 Courtesy of Potomac Yard; Richmond, Fredericksburg, and Potomac Railway Company. 27 EXHIBIT 3-13 SAMPLE DAILY STOP REPORT NC!HI->BClI'NO D Pl v C 10 0 ~I-'rp PEPCRT AS r~ O~~5 61l0/PO IN/OV T RCIoD COOF PC -I !!O-2 PFP-3 CC-4 SOU-5 Set-? ICPO INTT ~UP'BER "'0 l/ E RO r: TENTS I"BTrN6TTON ('(NSIGNEf S Y/',B CL TP'E OAT~ DE FEC T I-'''S CC'P'MENTS P PH i'711 8 l 1;1 PAPHI PHPERElL "A II F" I~ 1 ~ !I 0415 fM OIl"HIi rR C'N «;7 •• •• N RS LX 11C21 0 L ~1 Pl qC HAVDEGRIoC "'0 OIoiEIIlINO 1~4 (1055 ·tCCl ~ IP IIRAKES rNO~. 9 R RIIGX 11091 B 71 Tfl(~f'1I SCRANTON PA ~ E IGrl1l'\rt-J lC;O 0200 H9 DGrl1 BUlGF'" 27 E FL I 7~fl G F 71 EP'1lTY S PAPT "'0 BETSTEEl 112 1n5 M'9 Cl!T lEVF" ]0 ~ srl 20591 B l 71 PPRPPO rI-iE~TfR PA SC(PloPfl! 112 1440 607 ClA~C:YOS,",CP t-3···· B CC 23 O. 51 P E 44 "'TV rlilfl" IllS t'n t'.AIIP~PCL'P )(39('1 (I?20 tce rTI-IFI< 1;1·· l GAT)! 6~271 TIl E 77 E"'PTY SOL VAY NY lC PCI-fl" If' 176 1159 t04 BP" p GA TJ( 6561:11 TV 7Z 'CI(I BAlTIMCPF 1"1'\ D Elf'I-E" IC 2 c,0 Of-OJ t-06 C EN TEll TP6IlFII c5.· •• p set 11411?1 F l 51' INGH t: .HHHHCI~ MI" QIHl'CHF 1 ~ t 0255 tC7 PI1AKF IITG(;TNS 7~ •••• T ('P 301041 'F != 51 MTY ~AlTP'ORE MD AGF~'T 154 0130 bC" ClASSYOS'"'OP ~? .. Y PC 369201 Rl( F 77 E"PT't R rCI-'MQ"I1'\ VA AGENT II? ,~~ (\ 6(111 (" AliI< HI! Til rN 311 srL f3" 3f1l !! l 7' PULPPD SYOSSET NY r:1( fAI"ECrp 110 0030 tOf:. Cl ASSYOSl-lr O ·101 .. •• T NO: 2~32 B l .. 1 oUlPPD l FV JTTC~N PA "l'l T rr ~I( 15t 0230 f-oe rL ASC: YOSI-ICo 51···· A SCt 1'26~ B l 71 FURl.) I-IrRSFI-'EAO NY P FR H'RN TT 176 1020 6rt SIll,STFIJ ~1··.· T SOC 16732 ~ F 33 EP"PTY ~PP~~S PA ClE~~ClJT 12(' Oleo 6re OCCP,STf'lE 52" P AC F X 24622 Tll E 5f. E"PTY SCI-IFNfCH NY GENElFCTP 1 ~ 6 0025 f.!'9 CTl-lfP Z9 Courtesy of Potomac Yard; Richmond, Fredericksburg, and Potomac Railway Company. 28 • Individual car throughput. time ~n yard Louis-San Francisco railways, about 6,200 versus a standard. reports a month are now paperless. Of this number, in July 1977 Southern only found 23 • Percentage of time that the hump ~s in exceptions (Isenberg, 1977). Illinois Central use. Gulf Railroad reported in 1979 that 43% of its interchange volume was by paperless transfer • Amount of time required for trimming (Hall, 1980). Electronic interchange transfer operation. requires fewer employees and less paper and storage. and it provides faster, more accurate • Switch engine utilization (cars per interchanges with a complete audit trail. engine hour). 3.2 COMPUTER FUNCTIONS 3.1.10 Interyard Information Processing This discussion of yard MISs is limited to the Inventory data and management information are functions of the yard inventory system. Figure only used within the yard and by the railway's 3-1 depicts the relationships between the yard central office (systemwide MIS) because the 'MIS functions, and Exhibit 3-14 lists the information pertains only to conditions within products of those functions. In this.section. the classificatio~ y~rds. Consist; interchange; the MIS software functions are described in and financial .information. on the other hand. chronological order. parallel to the physical may be sent to other rail yards and/or to movement of a car through the yard, and a more another railway. detailed discussion follows on the structure of inventory files and their relationship to fre 3.1.10.1 Consists. In a manual system. the quency and order of inquiries and reports. consist information arrives by teletype or as a paper tape and is reproduced on a punched card In this discussion, a number of references to for the PICL (Railway Gazette. 1965). With a the inventory files are made. Typical yard data computer inventory system. the information· may bases divide the inventory records between three be entered as paper tape. cards. or via a C~T files: the car index file. in car ID order; the display. When two computers are linked together . car record file. in random order; and the track or share a common central computer. the inventory file. in track-standing order. The information can be transmitted directly. distribution of data between these files is determined by how often any item of information As detailed in Section 3.1.3. consist informa is accessed by car number or track order. Any tion is stored as part of. the PICL of. the clas information that is rarely accessed is stored in sification yard. When the train departs. an the car record file. That file is structured to advance consist as well as an estimated time of save memory space but is more difficult and time arrival are sent to the destination yard of the consuming to access. outbound train. 3.2.1 Overall Functic:mal Description 3.1.10.2 Interchanges. The processing of interchange reports can be assisted by the 3.2.1.1 Inbound processing. An advance consist systemwide MIS and computer-to-computer may have to be translated into the standard for communication. Incoming receipts require as mat of the yard, especially if it has been sent minimum data an equipment code. initial and from another railroad. When the train arrives, number, and loaded or empty status indicator. the consist is confirmed, and a receiving yard For loaded cars terminating within the yard '·s inventory is created, as follows. district, the contents and industry's spot number must also be recorded. These data are (1) ~eceive advance consist' usually received by telephone, teletype, tele copier, or message delivery. Other data are • Input entered upon receipt of the waybill. When all data have been received, the MIS computer auto - Train ID matically reproduces statements and audits - Estimated time of arrival foreign statements (McClellan, 1977). - Individual car information. Paperwork on the outbound trains can also be • Output interactively produced using information from the yard inventory system· and waybill. Individual car records - Train arrival record with estimated A second use of computers is the transfer of mix of blocks. interchange information. By sending information electronically, some railways have eliminated • Processing--The MIS computer or a the exchange of interchange reports printed on front-end communications processor paper. In the case of the Southern and St. communicates with the sending computer. 29 FIELD EQUIPMENT PROCESS CONTROL COMPUTER SWITCHING . CLASSIFICATION OF CARS TABLE INBOUND OUTBOUND ADVANCE CAR INVENTORY OUTBOUND COMMUNICATIONS COMMUNICATIONS CONSIST TRAIN LIST PROCESSOR SYSTEM PROCESSOR MANUAL SEARCH TRACK REPORTS INVENTORY FOR STATUS AND UPDATES CAR REPORTS ALARMS FIGURE 3-1. YARD MIS FUNCTIONS Information on the train and individual (3) Create receiving yard inventory cars is received, acknowledged, and checked for errors. The incoming car • Input information is translated into the format of the individual car record used - Record of actual car order and ID in the yard inventory file structure. numbers. Train arrival information and a count of - Train arrival report. car destinations are stored as a train - Individual car paperwork (waybills arrival record. and consists). (2) Empty car disposition • Output • Input--Arriving car record of empty car. - Standing-order track inventory of re ceiving tracks. • Output--Confirmed destination for car. - Upgraded car record. - Arrival record in history file. • Processing--The destination or block of all empty cars is checked by sending an • Processing--Verify car order in arriving empty car disposition inquiry to the train by observing videotape or receiving railroad or to yard or the television ~onitor; via ACI; or from systemwide MIS computer to confirm the inspection report. Verify and upgrade existing destination or to inquire individual car recorda from waybills. whether any exists. The car record is An interactive MIS computer allows updated when a reply is received. The completion of this function on a CRT central or systemwide MIS computer may terminal and keyboard. On the also perform the function of completion of the record verification, communicating with external yards or the car records become part of the railroads. inventory car record files, and the 30 EXHIBIT 3-14 YARD MANAGEMENT INFORMATION SYSTEMS Detailed Car Record • Update train approval/departure history. • Detailed individual car records • Move detailed car records to history. • History of car movements in yard • Prepare advance consists. • Waybill consist information. Inventory ~eports Inventory of Cars by Position in Track • Track-standing inventory. • Track-standing inventory (track ,. Track o'ccupancy from inventory records. occupancy from PC computer). • Inventory 'summa''ry by track, total • Limited:individual car records;(weight loaded/empty cars, tonnage. from PCicomp~ter). • 'Hump sequence (humping order of l.nbound • Reco~aj:of cars in shop and hoid tracks trains as determined by operational criteria)'. • Industry, track inventory. • Inquiry by car ID, locaiion, status, Arrival Processing weight, block number, arrival/departure time. • Add car records to detailed car record • Track status. • Add cars to inventory of receiving yard • Track overflow ~eport (distance to • Input inspection ,report vi,a CRT terminal couple from PC computer). ,. Update traiw arrival record • Traffic evaluation inquiry, length of stay in yard. • Update, train arrival/departure history. • Cars/tonnage per track or block or Classification outbound train. • Determine train humping sequence. • Per diem by block. • ' Provide automatic classification and • Alert tracks that need to be pulled • track assignment. • War~ings/alarms from PC computer. • Provide automatic swing (depends on operational criteria). • Arrival/departure summary report. Car Movement~-Inventory Update • Shop reports. • Receive inventory updates from PC 'Other computer. • Resource scheduling • Record moves made independent of the hump, or arrival processing' (via terminal • Dynamic track assignment or manual input). ' • Accounting. • Produce inventory update report. CommunicatiOns Departure Processing • ,To/from. PC computer • Monitor train preparation. • Advanced· consists -. Prepare consist report. • Empty car dispo:;;ition inquiry • Print outbo~nd train 'sheet. • Waybills • Upda~e i~ventory and 'train departure record. ' • Interchange repo.rts. 31 inventory of the occupied receiving yard Block or destination inquiry from tracks is updated with the standing systemwide MIS or other yard or rail order of the arriving train. The road. arrival is recorded in a train movement history file. • Output (4) Upgrade car record with inspection report - Track assignment for each car in car order. • Input-~Inspection report. Block or destination inquiry to system wide MIS or other yard or railroad. • Output • Processing--If the car' record contains a - Updated car record with inspection block assignment; a track assignment is time. made from the classification table. A - Reclassification of damaged cars. block assignment may be swung from one track to another if the normal track is • Processing--Inspection records are full, if the track allocation has been entered directly via a CRT terminal or changed (dynamic track assignment), or as a batch input. The inspection time if the car is a bad order or exceeds a and results are recorded in the high/wide restriction. individual car records. Any cars that must be rerouted to repair/shop tracks If a block number has not been assigned or to hold tracks because of a high/wide ~nd it cannot be made from the destina restriction receive new corresponding tion on the waybill, an inquiry must be classifications or block numbers. made of the receiving railroad (empty cars) or the systemwide MIS computer. 3.2.1.2 Classification. Classification of cars Similarly, if the destination of the car is completed via a hump or flat switch movement. is unknown and unavailable from the way Cars in the receiving yard are sorted to a track bill, an inquiry must be made. Other with cars of the same block or destination. The wise, the car is classified onto a hold MIS computer determines the proper classifica track. tion and records the inventory changes. The process is as follows. (3) Communication to PC computer (1) Train humping sequence • Output--Track assignment. • Input • Processing--Transmit to PC computer track assignments for the train to be - Estimated block mix of arriving humped. The file size within the PC trains. computer determines whether track - Estimated time of arrival of arriving assignments are transmitted immediately trains. before humping or whether a number of Receiving yard inventory. and length assignments can be stored in the PC of stay in receiving yard. computer before humping. - Classification track occupancy. Outbound train connections. 3.2.1.3 Inventory Update. Car movements made before departure makeup and made independent of • Output--Order of trains to be humped. humping or train arrival must be entered into the MIS computer to keep inventory records • Processing--The simple.st method of accurate. The process is as follows. scheduling the classification of trains is to hump the earliest arriving train (1) Inventory update from PC computer first--first-in/first-out (FIFO). A more elaborate scheme is to classify • Input specific ~rains out of order so as to provide more cars to meet the calling - Track location of each car. times of outbound trains. If any train - Misroutes, bad-order cars, hold cars, has been in the receiving yard over a swing cars. certain length of time, it would - Car weight. automatically be humped first. - Distance-to-couple changes. - Track status changes. (2) Track assignment • Output • Input - Updated car record (location and - Receiving yard track inventory. weight). - Car records of cars to be classified. - Updated track record (number of - Classification table--Destination/ cars, occupancy, status). block number, block number/track. 32 • Processing--If only the track location information on the train and its contents is is sent from the PC computer after forwarded as an advance consist. Car records humping, only exceptions from the switch for departed cars are removed from the active list need to be returned. Otherwise, a car file and transferred into a history file or record for each car must be sent·, either logged and then deleted. as a group or as each car crosses the clear point of the classification track An additional function of outbound processing is and is no longer under the control of the monitoring of outbound train preparation the PC computer. This record includes including the movement of cars from classifi the car ·weight for each car. If track cation to departure tracks. The outbound pro status and distance to couple are kept cessing steps are the following: by the MIS computer, these records are also passed to it from the PC computer. (1) Monitor train preparation Changes in weight and car location are made for each car record. The track • Input record is updated with the number of cars, distance to couple, track - Train departure schedule. occupancy, and status changes. - Tracks/blocks to be pulled for each train. (2) Other inventory update - Departure track occupancy. - Crew and engine availability. • Input - Car record for cars of applicable blocks, including car length and - Car number or old car location weight. - New car location. • Output • Output - Crew assignment. - Updated inventory record - Track makeup instructions. - Updated car record. - Graphic monitoring of departure. - Available departure tracks of required • Processing--When a car is moved in the length. yard, the change must be recorded in the - Engine requirements for weight pulled. yard inventory. If terminals are located in the field, the change may be made • Processing--A number of techniques can directly; otherwise, a call is made to be used to help with departure train the computer operator or to a terminal makeup. The train departure schedule location to report the car move. This notifies the trainmaster of train calling function is also used to reorder cars ~n times. Classification yard inventory inventory if a mistake has been made. information can then be used to display for the trainmaster the location of cars (3) PC alarms to be pulled. Departure yard occupancy and the total length of cars to be • Input--Alarms from the PC computer. pulled determine possible departure tracks. The total weight of the train • Output can be used to specify engine require ments. The makeup crew schedule, if - Notice to operator/users known to the MIS computer, can be used - Log file. to assign crews to the makeup operation and issue crew assignments. • Processing--Alarms and warnings from the PC computer may be sent to the MIS All this information can be displayed computer for display on terminals or for graphically to the trainmaster-and/or recording. yardmaSter to assist in decision making. As each task or move is com (4) Inventory update report pleted and the trainmaster is notified, the monitor program is updated to monitor • Input--Inventory changes. the train preparation. Similar methods may be used to monitor inbound trains. • Output--Log report of changes. (2) Prepare consist report and outbound train • Processing--All inventory changes either sheet via the PC computer or yard movements should be reported to inform the yard of • Input changes made. - Inventory of departing train 3.2.1.4 Outbound Processing. Once a train Car records of departing train departs, inventory records must be changed to - Engine and crew of dep~rting train reflect the loss of cars. Additional informa - Departure time. tion on the departing train is stored, and 33 • Output to maintain the accuracy of the yard inventory. Examples include pulls, flat switching, rese - Consist report quencing, coupling tracks, and cars pulled from - Outbound train sheet. shop tracks. • Processing--Individual car records are If a single car has been moved, ,its identity and compiled for the consist report, a new location must be entered. Car identity can printout of the advance consist. The be made by car ID number or by the position of outbound train sheet contains train the car in the track (e.g., track 35, line 14). departure information: tracks pulled, If a car is identified by its ID number, a file engines used, crew used, cars in train, in car ID order with a reference to the track . total length, time called, departure location is helpful to find the .correct inven time and track, train symbol, and tory file location to be changed. If the car -is destination. identified by track and line number, a file in car ID order is not needed. The new location (3) Update inventory and departure records may also be identified by track and line number (track 35, following car number 16) or by car ID • Input (following car number XXX1234). - Outbound track If a group of cars is to be moved, the cars may - Departure time. be identified by a range of cars (~ars IDI to car ID7), track location (track 17, cars 15-32), • Output or by relative location (car IDl plus six cars south or track 17, line number 15 plus 16 cars). - Inventory adjusted' for departed cars. - Departure record in histo~y file. 3.2.2.2 Search for Car. Searching for a speci - Detailed car records are moved to fic car is difficult if all car records are in history. inventory order. In that case, :the user must search sequentially through all inventory • Processing--The inventory of the records. If a second file listing cars in car departure track is used to move each ID order is available, processing time is saved detailed car record to a history file by searching this file. after the train departure time is added to the record. The inventory is then A method for saving file space {s to create a updated to reflect the departed cars. A "hashing" algorithm. A well-defined hashing train departure record is created for algorithm evenly distributes cars among equal the train departure. size "buckets" (file location). When a search is made for a car by ID ~umber, a hashing key is (4) Advance consist computed and only this bucket need be searched for the car. The algorithm creates artificial • Input classifications that are randomly and evenly distributed, in contrast to actual car ID num - Consist record bers, which are unevenly distributed because of - Car report. a n~mber of factors--traffic flow, yard loca tion, time of day, season, and the like. • Output--Advance consist. 3.2.2.3 Track Status. An often-requested re • Processing--The MIS computer or port is a track report listing cars in inventory front-end communications processor order. The frequency of this report and the compiles advance. consists for the amount of additional information required influ departing train from the consist report ence the. amount of information kept in the track and car records. This information is standing inventory file. In addition to car ID, translated to the format of the outbound track reports often include location, loaded/ consist and of the receiving computer. empty status, contents, destination, and weight. In this case, if this report is requested often, 3.2.2 Inventory File Structure the track-standing inventory file maybe de signed to store car ID, loaded/empty status, The structure of MIS inventory files is deter- contents, destination, and weight. Exhibit 3-15 .mined by available storage srace, processor is an example of a track inventory file contain efficien~y, and the frequency and type of infor ing often-required information. mation inquiries and inventory changes. Most MIS inventory systems are bound by CPU or re If additional information is also needed for sponse time; therefore, the structure of files other reports but less frequently, it is usually should allow for efficient compilation of stored in randomly accessed car record file to reports and inquiries. save storage space. 3.2.2.1 Manual Inventory Update. When inven 3~2.2.4 'Levels of File Structure Sophistica tory changes are made within the yard and are tion. This section discusses the three levels not automatically reported (arrival, humping, of sophistication used in inventory file struc and departures), they must be manually reported tures. The major objective in file design is 34 EXHIBIT 3-15 SAMPLE INVENTORY FILE Pa~e _1_ or 1 File NRrne _....;C::..:L::..:I:.::.NVF~-=I~L.:::E ____ DescrlnLion Cars Located At Potomac Yard ~ Industrial Characters p~r Record__ l_l __ Record!! per Block ---!±L Revision 110. Date ----- Runs Using This Rec·oro __I:..-..!I.!!N~B~OU~N~D:.!2,-- ______ FH.LD nr:r..A TIV E IIUMJI Ell I'RCXJ RAM NUMBER POOITION OF CIIAR MODE DESCRIPTION REF~ENCE ACTEHS 1 0 4 X Car Initial 1 -T-- --1;- 3 K . ___ S:ar Number _ ='T -- --3- 7 ._____ 1 X L = Load E = Empty. ______1 ___ ----1.-'--.-.--1--_ D = pangerous 1 ----1- ______1--____ X = ~xp10sive ------i -- ______._ G = Liquified Petro. Gas ---1--'- 4--- 8 ._~. R Gros:;_.Tons ___. ______1 ___ 5 .9 ---1.... R ..c.1.sssification Track I ---..6.... _ ---1.L--t- 1 R Ac tud Track i ------. ------+----_. ------+------_. --.------~.-----I ------<------1------_._------.- --_.. _- -.------_._-_. ------.-----.---. ----.- ---.------.- . -_ .. ------.- f---.---- .------1------.. ----. ------.---.-l------l------. -- .. ------I -----f------.------.------1------.-----.-+------f------.. --. -----t---.------.. - --_._-----_. ---_ .... -.-.- -.-- --_.. _------I-----l-.--~------.--- --.. ------._------.. -_. ------/----.--...... ,------.1---. ---+------_.------~----.------I------'--j---·--·------..------+------,.-- -----1.------+.------l------.-.------. -----I ------1------1-- . ------.---.--- --.--.------j------+-----+------f------. - ----.-----+------1.--...------. ------1------1----_.--.------.. ------_. --.---.. -.------_. ------.-----... ------_.- -- - . ------1----..,..---. ------_._-_. - .... ----._----- .. - -- -_.- ----.-- - ._-_ .. - ---. ------_. ------_ .. --- -- .. - --.--.. -- - .--- -'- --1------. --.--.--.. - --- - .-... --. --.-_ .. - . ---,...---1--_.--.------.-,--'-1--" ---. ----f------.. ----.-.---- .----.. ------.--.------.. ------..------.--.------.. --- 1--",'-'- ---.. ------.. ------.. _._------1-- --- ·----1----·-- .---.------. -' ------.. - Courtesy of Potomac Yard; Richmond, Fredericksburg, and Potomac Railway Compeny. 35 to limit file storage requirements while or The inventory file has a block of storage for ganizing the files in a way that speeds proces each track. The size of each track area is used sor searches for frequently used reports and to record the maximum number of 'cars on the inquiries. Figure 3-2 depicts three file track; a table gives the address of each track structures. header. This is an inefficient ,usi of storage because partially filled tracks have extra stor Minimum Inventory File Structure--With a minimum age space. Inventory information is stored here, inventory file-structure, limited information as are car 10, block number, length, weight, and reports are available, and only inventory infor loaded/empty/special status. mation is accessible. The car record file con tains car 10 and track location, and it is best Car movements are made by track location or by -stored using a hashing algorithm to permit more track and car 10. Inventory is a sequential efficient searches for the car 10. file; therefore, any car deletions or insertions necessitate that the entire file be rewritten. This requires processing and file access time. MINIMUM INVENTORY FILE STRUCTURE INVENTORY FILE STRUCTURE WITH OPTIONAL MIS RATA DETAILED CAR RECORD CARlO CAR RECORD INVENTORY R-ECORD (HASHED ORDERI INVENTORY RECORD (HASHED ORDERI (RANDOM ORDER) (TRACK-STANDING ORDERI CAR 10, TRACK NO. TRACK 1 CARS IN TRACK (WITH CAR STANDING ORDER 10, BLOCK WEIGHT, (WITH CAR 10, STATUS) BLOCK, WEIGHT, LOADED/EMPTY / SPECIAL STATUS, LENGTH) TRACK 2 POINTERS TO CAR RECORD , . TRACK n FILE STRUCTURE OF COMBINED YARD INVENTORY AND MANAGEMENT INFORMATION SYSTEMS CAR 10 CAR RECORD (HASHED ORDERI (RANDOM ORDER) INVENTORY RECORD' TRACK HEADER WITH POINTER TO FIRST CAR • • LINKED LIST • FOR EACH TRACK POINTERS TO BLOCK ASSIGNMENT RECORD CAR RECORD INVENTORY RECORD HISTORY RECORD BLOCK ASSIGNMENT HISTORY RECORD RECORD BLOCK NO .. TRACK NO. F(GURE 3-2. THREE INVENTORY FILE STRUCTURES 36 The mlnlmum inventory file structure gives only history files for each car. Car record files track location by car ID. All other information contain car information and more extensive MIS is accessed by track location. Inventory list information. The-information is accessible from ings and switch lists are made efficiently, as pointers from the car ID and inventory files. A they are made in file order and require only one pointer to the block assignment file allows block file access. This file structure assumes that and track assignments to be changed easily. few inquiries will be made by car ID. It is most likely to' be used with an inventory simula The inventory file has a header record for each tion where events are posted to the yard inven track containing the track number, block number, tory file only after the physical movement. length, and length left and a pointer to the first car on the track. Each individual car Inventory File Structure with Optional MIS record contains car location and pointers to the Data--An inventory file structure with optional car ID file, car record file, and to the next car MIS data is designed to act as a yard inventory on the track. Car movements are made very easily system, interface with a PC computer, and keep a by breaking and remaking pointers ~n inventory. minimum of MIS information. In a typical config uration with this file structure, the majority The yard history file (Exhibit 3-17) contains in of yard MIS data would be stored on the system chronological order the car record of those cars wide computer located at a central remote site. that have left the yard within a specific period. Revised switch lists are sent at the end of The block assignment file contains for each block hUmping to update the remotely kept inventory. a description of the block, currently assigned tracks, secondary tracks, and companion blocks. The car ID file contains car IDs and pointers to The addition of the block description allows for car record and inventory files. These records more frequent, flexible changes as required by are also hashed into smaller groups for more dynamic track assignment. efficient file searches. If the inventory is double linked in two direc The car record file (Exhibit 3-16) contains most tions, inspection lists may be printed easily in of the required information, including any MIS either direction. Inventory updates may be made information. The information is easily acces quickly by changing pointers" and this facili sible from pointers from the car ID and inven tates the upkeep of a real-time inventory- tory files. Records are randomly stored to save receiving inventory updates as each car passes storage space. into the classification yard as reporfed by the PC computer. The inventory file (Exhibit 3-15) contains car records in track-standing order. This file con 3.2.2.5 Enhancements for File Structure. To tains only car ID, weight, block number, -and enhance file structures, a hashed ID file can be loaded/empty/special status. This is the mini used for fast access, but it uses more memory. mum required to produce switch lists and useful Many times, information is only needed for a car inventory inquiries without accessing the car in the context of an inventory inquiry. To save record file. This system would be expected to file accesses, the information most likely to be have static block-to-track assignments. Because required with an inventory inquiry should be this inventory file structure is an inefficient stored in the inventory file. If a switch list use of space, a trade-off is made between more is to be generated, all the information required efficient data storage and the data stored that should be in the receiving yard inventory file are often accessed in inventory inquiries. so that no other files- need be accessed. These accesses would require more processing and file access time if they were located in the car If the car ID is included in the inventory file, record file. The amount of car data stored in a car movement need only be specified by track the inventory file is kept to a minimum. In and ID, not by the specific location on the quiries may be made by either car ID or inven track. With mUltiple users accessing and chang tory location, as both have pointers to the car ing the inventory, the actual inventory position record file. Car movements may be made by track on a track may change quickly and the car move and position, track and car ID, or car ID; the may be made on an incorrect car if made by track last is the least efficient. position only. Pointers allow all car information to be more Points from the ID file and inventory file may accessible by car ID, inventory, or by sorted also be used to provide access to car infor subsets by track, weight, and/or block. No yard mation. This saves_storage because the indivi history is kept. This design uses more complex dual car records may be stored randomly. Changes software, but offers a wider and more flexible, in inventory location therefore do not affect range of reports. the location of the car record file. This method is a trade-off against keeping some of the infor File Structure of Combined Yard Inventory and mation in the inventory file. When the car Management Information Systems--This file struc record file is independent and reached through ture is designed to store more MIS information, pointers, it is accessible through either ID or provide an easily accessible yard history, and inventory files but is not as easily accessible easily change inventory as required by real-time for inventory inquiries as when the information inventory. The car ID file contains ID numbers is in the inventory file. The information most and pointers to inventory, car record, and often sought may be kept in the inventory file, 37 EXHIBIT 3-16 SAMPLE CAR RECORD FILE Pails _I or ~ File Name MASTERFILE Dsscription CARS LOCATED AT POTOMAC YARD & INDUSTRIALS Characters per Record 200 Recorde per Block ~ Revision No. Date Runs Using This Record 1 - INBOUND2 5 - RECOVRIC ------~~~~~~------ FIELD RELATIVE tJUMlIEll PROJRAM NUMBER POSITION OF CHAR- MODE DESCRIPTION REF&RENCE ACTms 0 I· B 'Sho~ Defect Code I .~ X______.- I 4 ~ In it i a I I 5 5 3 K Car Number I ~ B I X L=Load E=EmPtv I 5 9 2 -- r--~'- Kind of Car I 5 II I B Classification Track I 5 12 I ll. ___.. Ra i I road In I 5 13 I U - Ra i I ro~~ Out I 14 I B Gross Tons I 15 I B__ Net Tons I --L-+- 16 6 X Contents I ~ -1: ___ 22 q --D.e.sJj nat ion r:" tv I 5...-.- 31 2 X _. Des tina t ion State I -----.. -- - . 5 .JL- 9 -- _J__ . _C2nU9Me- 42 2 ~--- ~cial Ic:i1.cIJICtiCC:i 3---L._-L-. ....L_ .. ~ 44 --1 __ ..5.- - - 5 . X Qff-Goios JUC~tloD 4~ 4 X off.:.G2lnSJ.B.Q£l_d __ _ ----1- ...5....- ___IS ____ 53 3 _Origio Station th,lmb!l[ ---I I 5 56 1 X-- _.- Shop Reported Code _1_.~ 57 I - --~.--- X=INPCFILE P re~a i dlCo 11 ec t I 5 5B I K __ ~a~bill Month _1__ ...5....- ____ L. __ 59 I _Wa'ib ill Da:L_ .. I .2 60 2 r--J-- Billing Road Code I 5 62 3 K _Wa:tbi 11 Number I .. - ~ - J>5 9 - . --~----- Shipper I ~ 74 9 X Origin Cit:L I 2 B3 2 -~-- .Or Lsl!l..lli.1~ I 5 /j5 2+ X Final Road I _5_ B9 I lL Rout-os Cod !l =-.8.s.e.oL s'b.l.i29.e.r.. I 5 90 I -'L ___ Mo~e . . _L-~ ~_I_------I -.~--- -- ~'iP.!~Ch[~BL Ope r.a to r ___._ I 5 92 6 - X_._ ~r.rly~mbo I I 5 9B I __ X___ Arrival Motor Initial I 5 99 2 - ._1< ____ -Arr'i va ~otor'-Number I 5 101 .- __1___ - -,-J __. _ ...8.r.I:l'lE...L.S_~liy~ ____ I .5. --- 102 _1____ _K__ -Arrival l:io!,!r . I S ---- 103 I . - _t< _____ Arrival Minute I -L- - ~-.-- ArrTVa I Month-- 104 K .. I 5 --1--___-_. ---K_. _____ . ------105 f------. .ll.ui~_LQ~_ I _ .2 106 _1 __ - __1$ __ I-.!nters;hangli.l Hour _._. I .2 .--!Ql_-- 1 -- -~----- J ~~~r,=hang~Mi nUj:_e_ . ___ --- lOB --1---' K Interchange Month -:----}- Courtesy of Potomac Yard; Richmond, Fredarlcksburg, and Potomac Railway ColTlpany., 38 EXHIBIT 3-16 SAMPLE CARE RECORD FILE (Concluded) Pace _2_ or 2 File Name ------MASTERFI LE lll!scription CARS LOCATED AT POTOMAC YARD &. I NDUSTR IALS Characters per Record 200 Recordll per Block: _4_ Revision 110. Date ------Runs Using This Record ------I - INBOUND2 5 - RECOVRIC FHlD RELATIVE NUMllEfl PRCXJR.AM NUMBER POOITION OF CHAR MODE DESCRIPTION REFERENCE ACTEI1S 109 IK___ Interchange Day I 5 ___-t- __I!-'IL"O'-___ I __ .1.. ____ Uode . I .3- III __+- I X. U Cod_!L- ._ I 5 112 I X I-C.Qde .--l-._-1.------+"'--:-1-:-13~---t-·--;4'----._-+:__--..J..Ll..-. _-...,..·-t~Pigm.ack Initial - .. ___ J ..5 __ 117 3 K...f.l ggyback Number J 5 120 4 . .15 _____~_t2.m!'!aL.Trans.Commod~v No. I_~ ___-+_...... ;;;.124-:,- _ _t--:1=-----+-~-.--. ~tua I .Track (Locat i0.!!L I 5 ____-+ __ .!-r.;;.25;<.- _ _t---i5__ ----+---:;.X-- __ ~ epa r tu re Symbo I I 5 ____-i ___'T11 .... 310,.....-_--+ __2.-----+- ..- -,K __ Departure Motor Number I 5 132 I K Ordered Hour _ I 5 133 I K Ordered Minute I _~ 134 I ·-K---- j)rdered Month _. __I__ .~ _____1 __ 7'13=-:5~------1--___ =---K~= Ordered Day ____1_·_ ~ 136 I ____ L_ ~~rture Sheet .Number· . -, II ~ __ ___-+- __.,-;13:-;7=- ___ . 40 .. X Routing From SCL ______~.- ___:_- .L- 177 4 ___L_-.flaced Year,Month,Day,Hour I 5 ____1-_,,181r.1:- __+_-;:4:- __-I ___~ _____ ~l!ed Year,Month,DaYtHour I ._5 __ _ 185 2 K Industrial Patron/Locator -----+-..",.,,,.--,---1--;:----- _____ =~~ £o_d_e ___.. ____ .-:----=-.~-.,.,_--I-.-:..I-- _5 __. 195 5 K ._~~i fted Year,Month,Day,.Hour _I_~ __--= ______-+ ______------1---. __ .__ ~ nute . __1____ 5 __ - --.-- -~------I------...------f-----· - -.------. ------+------,------t------+--.------1------.------+::~~~~~~=~~~:~::~~~~~-+------=--===-+------.:=-~~.~--~·======-+I-=====-·~-=·:=· ------l------t------~-- .. ------.--- ··----1------t------r------...------1------·------~-1·------.----... ------.------.. ------1------1------+--'------If--.------I----·--t-----· -- ---. ------i------.-.. ------.------1------.~------. ------.. -.------j------I ------'----+------t------. -- ---.--.------.------+.------1------. -- --. -----.. ---.------+------1-----.- '------.--.------.--.. -----·------1------1------f------.. _-- . - .. -.------. ------ 39 EXHIBIT 3-17 SAMPLE YARD HISTORY FILE Pa~e _lor ..L File Nallle _ _'''cO... RRE...... ""c .... FI.... L ... E ______Descrip't,1.on Departed Cars Characters per Record 200 Recordll per Block ~ Revision No. Date _____ Runs Using This Record _.....::..5-~RE=C~OVR~I~C:..-______ FIWl RELATIVE tlUMlI Ell PRCCRAM NUMBER POSITION OF CIIAR- HODE DESCRIPTION REF&RENCE ACT EllS 0 1 X Sho~ Defect Code 5 --C-· 4 X Car Initial 5 -- --_.-__ 3 ------L._ 'K Car N\,Imbl:I ~--- L ___ _ -1 X L - Load Eo: Empty -L- -- ___ 9._._ 2 ._ X Kin4,...Q.f Cal: 2 __ ..11-_ -- -- _.- _ -1-._ R .tla.s:i1 UI;at 1QIl IUI;k. ....L_ 12 1 _11 .RailrQad -L-___ In ~------13 _..ll RailIQad Out 2 _...l4 1 R ~ross Tons .5 ---- ..l.5. __ -L-__ 1 ~ ..He.t. Tons 16 6 -X.... Contents --L.._ -- ._9 X 5 ---_. ....:.....2211 ______..2 ___ DI::3t1I1ati.QII City --.-X..-_. __ _Uestioat1lm...--~ ______L _ --- __11_·,_ _ -L___ -.-X. ___ J&n.SJ.gll~ ______. ____ _--L-_ --- __ l!L__ ' ~la..l..lnU.r.l.!..c.ti2ns_. _____ -~-- _.-X. .2-. ___ --- Qi.f.=.G.Q.:i.ng, .J.u.M..li.on ______..2. __ ----_.- -~--- ~~---- ~ --- --1L- J)li.~ng",.B,Q.q<;l____ --- _2-. ------~--- ..1C __ _.2. ____ ---. _iL_-_ 3 Qd.giJL.S.t..a.t.i..~rLl:Ij.1.mQ.~t.. ______--i6.. ______1 ___ Shoo Reootl.,ed Code ______5____ f---.X-----1l __ ~L- __ 1 _ ~crru PreHi.lSLCQ1l~_. __ _5 ____ 28 --L K Haybi 11 Month_ ____ .2. ___ --29. __' _. 1 K _WEbill I2a~ _2- ___ ---~. 60 2 K Billing Boad Code --_5____ 62 3 .- K \1a~bill Number ---_L 65 .. - 9 - X Shipper 5 74 9 X Qrir;in Cih-____5 __ 83 2 X _QtJ.Ri,n State 5 --_.- 85 4 X Final Road 5 __8_9 1 l\_ Routing Code Agent Shippe 5 ------___ 2 ____--_. _ 90 1:-._1 U Nove Tyee ---__9). ______1____ --- _5_____ ---- -~--- ~~nchLC_RJ' Oper~!9L _____ --- n . _----P_ ')( AI:!: i lid S;aDbcl .5. -- .. - _ .3~._ 1 ---X..- AII:i:llal MctQJ:.._lp..itiAL ______.2._ . -_ . __2.. ___ ----K ___ ....5.. ___ -- --.- -~---- Arrillal~~mber ------,---l.oL __ .. _ _-.-l. ___ K ___ _1l.r.I.:i.Yal...s.b M t N!.!Il1lutr ______. __ ..5 ____ ---- ..5__ . __ ----- _102 ---.!. K ArI1:lwl HQl,u;: - --.. ------1:---_._-----.------.------:------.------_._------.- .---.--- -_._--- --_._------.------_. ----' Courte.y of Potomac Yerd; Richmond; Fredericksburg, and Potomec Railway Company. 40 EXHIBIT 3-17 SAMPLE YARD HISTORY FILE (Concluded) POGe _2_ Of 2 File NRIlle! _~C::.;A::.:RRE=C::.:fc-=I:.=L=.E ___ Descr lpt-lon Cars Located at Potomac Yard & Industrial Characters per Record 200 Records per Block: _4_ Revision 110. Date _____ Runs Using This Record --'5;...-...;;.RE=C..;..OVR..;..;....;I"'C'--_____---, ______ FIELD RELATIVE tJUMlJ Ell. PRCXJRAM NUMBER POOITION OF CfIAH- HODE DESCRIPTION REF&RENCE ACT EllS --- _103 1 K Arrival Minute 5 104--. 1 K --IDival Month 3 10~ __--- ___ 1 -- K Arriv~ _2._ "-- 106 1 K Interch::mge Hour - 5 .-- 107 1 K Interchange Minute 5 -5-._- 108 1 K Interchange Month ------"--;-- - 109 1 K - InterchanKe DO!Y. 5 110 1 X D Code 5 -- III 1 X U Code 5 112 1 X I Code _5___ __4__ 113 X Pip;gyback Initial - 5 117 3 K Piggyback Number 5 ._-- 120 4 __K__ ._ _.Standard Trans. Co~?,,:!!.!:i..ll() 5 12-4-- --'-1-- __B__ --5--- Actual_.'!'rac~i19ca~j.onL-- _ .-- --12-5-- --5----- X___ --_.- ~arture Symbol ---_. _5_. ___ -130-- . __2______2 ____ 1------K peparture_tlotor Num~er ---- Ordered --- --~-- --~-- K _Hour_. --5----5 ---- 133 1 ---1<--- _Qrdered Minute ------11l:- ___ -.1...- K n,.,1 ",."rI "Month _---L __ 135__ __IL_ _1--_ ...ordered Da~ ---.------~-- 136 - 1 K ne~artu:t:e Sheet t:lumbe:t: .-5_ - __110 x _ B.o\LI:ine f:t:om...s.cL... ______.. _--L ----1-_131- -.5..-. __ 177 K Pl::tc~d • Y~ar. Month..J)~ _B:c...... ~ -. -2-__ lal ~ ----K ..flil.leQ.:.~L.MQD.th.....Dj!,Y-,.Jlr...... _--1 ___ .-.li!i-_ --K.. Indu~tr;l.al ~atrQIlLLQ~atQr --.-- ...QQ9.e __ -2___ ------L-___ 125 5 ---K...__ _Sbili~. ~!L.fu:...lli!).__ ------.'------f--.------.------. ------.------. f--.------"- ---_. --- ,---1-._--- -_._--f-- .------. .. ------, ------_. ------_. ------_. ----,-f------1--_._- ---- .----- _.- ---.. ---.... ------_.------ 41 while MIS and secondary information might be second inventory module must be :added by pro kept in the car record file. viding a pointer in the last record of the first module. Dynamic allocation of inventory file space may be used to save the excessive amount of storage A second method uses a linked l~st for each required by having a static memory record for individual car. As each car is added to in each possible physical inventory relocation. ventory~ the last car's pointer points to the The first method is to have a minimum space for memory location of the new car" When a car is car records in inventory order, for example, deleted or moved, the pointer of the car pre space for 40 cars' for each track. When more ceding is changed to point to the car following than 40 cars are in a single track inventory, a it'. This. method no longer requ~res that the in ventory file or module be rewritt.en 'upon every insertion or deletion. 42 CHAPTER 4: OPERATIONS AND FUNCTIONS OF THE PROCESS CONTROL SYSTEM The most connnon 'applications of the PC computer settings, and the order in which trains are to in hump yards are automatic routing and switch be humped. The hump conductor may visually ing of cars and automatic speed control. The verify that the switch lis~ and .actual train PC computer may perform many other functions in makeup agree. the yaid, however, ~ncluding routing trai~s from the receiving yard to the hump, generating the 4.1.1.4 Bad-Order Car Detection. The PC pin-puller's list, detecting bad-order cars, computer can also be programmed to stop the controlling hump engine speed, keeping the track humping process if a bad-order car is detected. inventory and car location records, issuing A dragging equipment indicator installed on the operational reports, aligning switches and pro hump lead sends a warning signal to the computer viding area protection during trim operations, when dragging equipment deflects the vertical and determining power requirements for makeup steel plates of the indicator, closing an operations. Exhibit 4-1 lists connnon PC electrical contact (Petracek et 'aI., 1976). functions. Inspectors can enter car numbers into the PC system via terminals located at inspection 4.1 RAILROAD OPERATIONAL DESCRIPTION points along the hump lead; bad-order cars are then automatically switched to repair tracks. 4.1.1 Receiving Yard to Crest Instruments to detect broken flanges, loose wheels, and overheated bearings may also be Trains in the receiving yard are ready for installed and interfaced with the computer. humping once the cars have been inspected and the brake systems have been bled. Train lists 4.1.1.5 Hump Engine Speed Control. Radio remote are updated in the MIS computer or in both the control can be used to regulate the speed of the MIS and PC computers to reflect any changes in hump engine. A requested speed is transmitted the makeup of the trains. These lists should be via radio to the locomotive's on-board control accurate before the switch list and pin-pu11er's system. The requested speed is compared with list are compiled. the actual speed measured by axle tachometers to control propulsion, braking, and emergency 4.1.1.1 Generating a Switch List. A central (as systems (DeIvernois, 1972). The requested speed opposed to a yard) computer may assign a classi may be constant, or it may be varied to maXlmlze fication code to each car in the train based on yard throughput by not having the speed set for the classification table (which contains the the worst-case situation (i.e., ~here a trailing classification tracks and the var{ous criteria car is likely to catch up to preceding car if for assigning a car to a particular track) and cars are humped too fast) (Petracek et al., waybill information (destination, consignee, 1976). Another method of controlling locomotive deliver-to-road, and so forth) (Martin & Durand, speed is to transmit recommended speed via radio 1974). The yard MIS computer translates this signals to the engine, where it is displayed to code into a classification track assignment, the engineman in digital form or as a colored which is passed to the PC computer in the form 'light (e.g., red = stop, green = fast, yellow = of a switch list. Alternatively, the classifi slow, flashing red = back up). cation table may be transmitted to the PC com puter from a central data computer, from which 4.1.2 Crest to Classification Tracks it generates classification track assignments for cars. 4.1.2.1 Automatic Routing and Switching. The switch list usually is transmitted from the MIS 4.1.1.2 Generating Pin-Puller's List. A pin computer to the PC computer. The PC computer puller's Ilst is developed from the switch list should have a switch list storage capacity equal and track assignment instructions. The number to the standing capacity of the receiving yard. of cars in a cut is determined by the destina If there is no provision for a stored switch tion of contiguous cars and the maximum allow list, an operator may enter the track destina able cut length. The pin-puller's list may be tions at a terminal when humping occurs or read in hard-copy form with written annotations or it them off punched cards. As a car goes over the may be a CRT display, which allows changes to be crest, its ID number is removed from the CRT made until cars have passed the pin-puller. display in the control tower. 4.1.1.3 Routing from Receiving to Crest. The Knowing the classification track destinations, hump controller enters humping requests (i.e., the computer progressively aligns the switches which receiving tracks to pull) at a terminal. for each cut as the cut travels through the Cars affected may be flagged to indicate they switching area. As a cut rolls forward, track are in transit to the crest. The PC computer circuit repeaters or loop circuit repeaters can align the receiving yard switches to route a associated with each switch detect the cut's train to the hump if the MIS computer has given presence and the switch is thrown in accordance it the receiving track inventory, current switch with the assigned track destination. Wheel 43 EXHIBIT 4-1 COMMON PROCESS CONTROL FUNCTIONS A. Receiving Yard to Crest G. Trim Lnd Routing to crest Switch alignment Swi tch alignment Control of inert skate Automatic B/O (bad order) detection (hot Track lock/unlock (last switch set away box, dragging equipment from blue-flag track) Automatic height detection H. Returned to MIS Computer B. Crest Weight or weight class for each car Pin-puller's list or display Distance to couple for each track Hump engine speed--radio control Inventory update (flag misroutes and B/O, Weight for inventory record and speed hold, and swung cars) control Final switch list update or individual update as car clears C. Automatic Routing and Switching Track status (lock/unlock) Classification guide received from MIS or I. Alarms manual input Cut length detection Misroutes Car identification and verification Track overflow Automatic switching--precrest to clear point Speed control errors Automatic swing to B/O or rehump track or Equipment failures when track c10sed Catch-up and cornering conflicts Car location update Stalled cars Alarms, correction/avoidance Short track circuit Distance-to-couple, occupancy measurement Missing, extra. out-of-sequence cars Editing changes to resequence cars D. Automatic Speed Control Track swing required (overflow or locked track) Weight scale input Hazardous car to be humped Weight classification Car out of order Distance-to-couple input Weather input J. Reports Calculate rollability Master speed calculation for single and Hump use multiple car cuts Total number of cars humped Master retarder control (feedback) Updated final classification list (note bad Exit group speed calculation for single order and hold/height exceed cars) and multiple-car cuts Log of manual operations Group retarder control (feedback) Log of stalls, misroutes, track swings, cornering/catch-up conflicts, and extra, E. Manual Rout ing and Swi tch Ali'gnment missing, and resequenced cars Speed distribution report and log of speed Manual reroute switching control errors Add or delete missing or extra cars in Log of equipment failures inventory (inventory adjustment) Log of track overflows Swing car to B/O or rehump Swing assignments Swing when track closed . Height restrictions for each classification Set switches for backing over the hump Manual hump engine control K. Inquiries F. Manual Override for Speed Control, Route Track status (lock~d, blue flag) Selection, and Switching Track occupancy (distance to couple) Associated swing assignment (B/a and rehump tracks) for each classification track Hazardous cars 44 detectors or car presence detectors are used to Distance to couple is determined by the use of prevent switches from operating under long cars track circuits. The axle acting as a shunt or cuts that span the track circuits. A wheel across the track circuit, the impedance of a detector sets up a magnetic field in a section classification track is measured from the of rail. When a wheel passes, it changes the clearance point to the nearest axle of the car field, inducing a current in a nearby coil. The that last entered the track. The impedance of electronic detection of this current indicates the rails varies directly with the distance from that a wheel has passed. The computer counts th~ circuit origin to the nearest shunt, so the pulses from the wheel detectors and compares correlating impedance with distance to couple 1S them with the known number of axles (which were possible (Petracek et ,aI., 1976). For cuts counted by wheel detectors near the crest). A longer than a specified length, an arbitrary presence detector senses that a car is over a rolling resistance factor is applied, based on 'switch by detecting a shift· in frequency caused the number of axles and weight. The length by the car passing over a coil that controls the above which a roning resistance cannot be ob frequency of an oscillator (Petracek et al., tained depends on the length of constant grade 1976). between the crest and master retarder and the intermediate and group retarders. Photosensors In addition to ensuring that it does not throw at the crest determine the length of a cut. a switch under a car, the computer checks for cornering po~sibilities and stalled cars (cars 4.1.2.3 Car Location. PC sy~tems track cars as stopped short of the clearance point) before they travel from the crest to their respective setting switches. If either of these situations destinations in the classification yard using exists, the cars following are routed to a bidirectional wheel sensors. The PC inventory fouling track and a misroute is reported. In may be stored until all cars in a train are the case of cornering,* the following car may be humped, at which time it is sent to the MIS routed to the same track as the preceding car, computer in the form of an "as-humped" list. and a misroute is reported. Alternatively, inventory update records may be transferred to the MIS computer as each car High cars, wide cars, and overweight cars can be reaches its designated classification track. automatically routed to special tracks unless the Sensor inaccuracy, mistakes in pin-pUlling, and hump conductor manually overrides that assignment the like cause discrepancies between sensor and sends the car to the track assignment of its obtained tracking information and the switch original destination. The hump conductor's con list and pin-puller's list. Corrections are sole'may have various pushbuttons for routing entered to reflect the true location of the cars. cars to loaded repair, empty repair, hold, and In some cases, the PC computer provides such MIS clean-out tracks. Any misroutes or swings are functions as an up-to-date listing of all cars logged and theri reported to the MIS computer. in each of the receiving and classification iracks and an up-to-date record of total tonnage 4.1.2.2 Automatic Speed Control. To determine and number of cars on each receiving and classi the correct eX1t speed of a car from a retarder, fication track. A record of each car may also the computer combines the following information: be kept in track entry order and switch list car acceleration, car weight, distance to couple, format. track grade and curvature, route information, and weather and wind conditions. Track grade 4.1.3 Classification Track to Departure Track and curvature and route information are already in the computer at the time of humping. Field 4.1.3.1 Align Pullout Route. If the trim-end sensors are used to collect the other measure supervisor wishes to pull a cut of cars between ments. the classification and the departure tracks, he can enter this request on the PC computer from When a cut of cars rolls down the hump, wheel an on-line terminal. Signals are sent to align detectors or photocells sense its presence and the switches between the classification and signal the computer to monitor the radar output departure tracks. Providing 'there i~ no con (Williamson et al., 1973). Radar measures car flict with a protected or blocked area, the speed by sending out a beam of radio waves and switches are aligned. The supervisor releases measuring the reflection of those waves off the the area lock after the pulling operation so moving car-using the principle of Doppler fre that other pulling operations can occur. quency shift. Velocity measurements are taken ahead of the master and group retarders. An 4.1.3.2 Makeup Requests. Via an on-line ter electronic coupled-in-motion scale measures the minal, yardmasters enter train makeup requests weight of the cars. Each axle load is measured specifying classification track numbers from separately and then summed to obtain the gross which trains are to be made up, initial and num weight of the car. ber of the first and last cars of the block, location of the transfer in the yard, and avail able road engine power. The computer then up dates affected inventories and prints updated *Leading and trailing corners of two consecutive inventory summaries in the yard office. Gross cars collide because of insufficient separation car weights (determined during the humping at a branching point. operation) are added (starting with the first 45 car of the first classification track specified) 4.2 COMPUTER SOFTWARE FUNCTIONAL DESCRIPTION until the total weight equals available engine power. If the yardmaster has requested too many 4.2.1 Operating System: Executive Program or too few cars to be pulled by available power, the PC computer reports this. The PC computer The operating system hardware controls the in also reports if the requested power for the total. ternal operation of the computer hardware and weight is exactly correct. The yardmaster can software systems. The operating system is also then obtain additional power, add cars, or called the executive program, system monitor, or proceed as planned, depending on the report he system supervisor. It is a collection of pro receives. grams, many of which are provided by the computer vendor and refined or augmented by the user. The Bidirectional wheel sensors can be used to count real-time operating system for the railroad clas axles as cars are pulled from the classification sification yard PC application is a specialized yard. The computer notifies the pullout clerk and often yard-dependent system. It should if the car tracking data do not agree with data perform the following duties: already in the computer. The clerk can then take the necessary corrective actions after viewing • Acc~pt interrupts from I/O devices, time the move by television camera or on videotape clock operator, and so on and maintain (Martin & Durand, 1974). This function can also job request queues. be performed by the MIS computer (Section 3.1.7). • Schedule and allocate program execution 4.1.4 Operational Reports times in accordance with the priority levels of the programs and the resources The PC computer can be designed to produce a available. number of operational reports, including: • Allocate spaces in both main memory and • Misroutes. secondary memories and perform file management (i.e., program loading, • Full track. overlay, linkage, and so forth). • Speed errors. • Perform utility functions, such as operator interface, failure detection • Equipment failures. and management, accounting for computer utilization, file protection, and the • Destination change. like. • Total time of hump use. Figure 4-1, a conceptual representation of a yard PC computer software system, indicates the • Number of cars humped. relationship between the real-time operating system and the other software subsystems. • Final switch list. The software functions of a PC computer in a • Updated switch list after humping. hump yard may be considered from two standpoints: (1) the geographical area of the yard or (2) the • Swing assignments. nature of the function. Geographically, the PC computer covers the following areas: • Classification track assignments. • Precrest (from receiving yard to the • Operation logging. crest). • Pullout query. • Crest. • Technician and yardmaster reports. • Crest to master retarder. • Height restrictions for each • Master retarder to group retarder. classification. • Group retarder to tangent retarder. • Updated group tally. • Tangent retarder to coupling point. • Receiving yard tally. • Pullout end and departure yard. • Classification track inventory. The PC computer software can be grouped • Inventory summary for yardmaster. according to: • Departure yard log. • Sampling routines • Data reduction routines 46 OPERATOR INTERFACE REAL·TlME OPERATING SYSTEM LIBRARY BACKGROUND PROGRAMS JOBS LANGUAGE REAL·TlME DISPLAY MANAGEMENT PROCESSORS FILES PROGRAMS REPORTS CAR COMMAND DETECTOR IDENTIFICATION AND SCAN AND CONTROL SPEED MEASURES ALGORITHMS ! SOFTWARE ------ COMMUNICATION NETWORK IN YARD FIELD SENSORS SWITCH AND AND DETECTORS RETARDER CONTROL CLASSIFICATION PROCESS FIGURE 4'1. CLASSIFICATION YARD PROCESS CONTROL SOFTWARE SYSTEM • Control function routines The data reduction software is essentially a continuation of the sampling routines, whereby • System monitoring and MIS routines. raw input data are translated into information useful for decision making. For example, the Depending on the field devices under the PC com activation of a wheel ·detector is translated, puter's surveillance and control, the sampling along with other input information (e.&., system technique can either be on a fixed-time incre clock time), into car speed. ment bas·is (cycling) or on an event-occurrence basis (interrupt). The determination of which The control function routines generate control technique to use is a trade-off between data signals from both input data (reduced) and pre resolution and computer resource cost. stored control parameters and decision rules. 47 The system monitoring routines manipulate and • Switch alignment for front-end trim organize the existing input and output infor operation. mation into statistical and management reports. • Area trim protection. The software packages currently in use are briefly described below. 4.2.4 Crest to Master Retarder 4.2.2 Precresi Control The purpose of the postcrest,PC function is to check arid verify pin-pullers' ~~(ions, collect The precrest control function covers the pro car velocity' and other physical data for speed cessing of train arrival information that is control, and update the car inventory. This relevant to the automatic alignment of the function is aided by wheel detectors, photo switches from receiving tracks to the hump cells, radars, weight scales, and so forth. approach. In this function, the information on arriving trains and certain operational manage The typical routines (see Table 4-1) are as ment decisions (e.g., the classification table, follows: the switch list) are transferred from the MIS computer to the PC computer. ACI reading and/or • Postcrest wheel detector processing. receiving inspection reports will correct any last-minute discrepancies that have existed • Photocell detection routine. between the train consist and the physical inventory (Section 3.2.1.1). • Radar detection of cut length. While the inventory data of the receiving area • Determination of car axle count. are being verified and corrected, the operational management decision function of the MIS is gen • Posthump car 'identification and erating track assignment decisions based on pre verification. established criteria, classification tables, decision rules, and the current and predicted • Weight scale routine. track utilization of the yard. The track assign ment determination is a necessary step for gener • Weight classification. ating the switch list, pin-puller's list, and the routing sequence from the receiving tracks to the 4.2.5 Master Retarder to Group Retarder hump. At this time, the PC function receives the st4itch list from the MIS function. The PC com (1) General puter performs automatic routing from the re ceiving tracks to the hump and maintains precrest The PC computer functions from master re car inventory. tarder to group retarder are to check and verify pin-pullers' actions, collect car This function is usually supported by two major velocity and other physical data for speed routines: the routine for automatic routing control, and update the car inventory in from the receiving tracks to the hump crest and the posthump file. As cuts enter and leave the receiving yard inventory routine. Table 4-1 the master retarder track section, the summarizes the input, process, and output for speed control function detects and measures these routines. the presence of a cut and its velocity and determines retarder control action. At the 4.2.3 Crest Control same time, the software function monitors changes in track inventory. Although the The crest control function extends from the routing of cars and switch alignment are receiving leads through the crest. The determined at the hump, an elaborate set of principal function is to ascertain humping .witch logic software routines is required sequence, effect accurate pin-pulling, measure in the posthumping process to prevent and control hump speed, control and verify misroutings, collisions, and derailments. proper routing, and initiate corrective actions when necessary. Under this function are eight (2) Master retarder control software routines (see Table 4-1): • Input • Route and engine control. - Axle passage detection from wheel • Determining optimal hump speed. detectors placed before the master retarder. • Generation of pin-puller's list. - Velocity reading from entrance radar • Hump wheel detector input processing. unit. • Hump speed calculation. - Car speed control i.nformation (e.g., weight class, cut length, height), • Hump operating display. - Requested'release velocity. 48 Table 4-1 SOFTWARE ROUTINES FOR PROCESS CONTROL COMPUTER Routines Input Process Output PRECREST CONTROL Routine for auto Receiving track inventory This routine is to align the switches so as Command to align receiving yard matic routing Switch list to move the next batch of cars from the re switches for the next batch of from receiving Track assignments list ceiving tracks to the hump in accordance with cars heading for the hump yard to crest Current switch settings humping sequence. Receiving yard Train consists This function can either be performed by the Car ID by track and by position inventory routine ACI data MIS computer or the PC computer, or both. If to be maintained in the PC com Receiving inspection report automatic routing from the receiving track puter on-line file to the hump crest is to be done by the PC computer, a requisite is that the PC com puter have on-line' access to the inventory file by car, by track, and by position. CREST CONTROL Route and Switch alignment settings This software routine is to ascertain whether Go or no-go signal to hump shove engine control from receiving tracks to the route switches from receiving tracks to lights crest hump approach are aiigned properly, in Speed category number to shove \D""" Hump speed instruction from accordance with the automatic routing plan lights dynamic speed control cal generated by precrest control route selection Speed control command to cab culation or from a pre software. The control signal is sent out in determined average speed one or more of the following ways:' Current hump signal status • Go or no-go signal to the hump shove light. from the hump approach This is the simplest form of control command. track circuit • Simple speed control instructions to the Automatic routing plan shove lights, e.g., stop (red). fast (green), as generated by pre or slow (amber). crest control • In a more automated system, the speed con control instruction goes directly into the cab engine control. Determining Desired yard throughput This routine helps 'to increase the throughput Speed control instructions to optimal hump parameters of .the yard by assigning the highest hump hump engine speed Penalty factors (as a speed feasible;' yet at the same time it tnus-t function of the routing minimize the probability of misroutes due to and attributes of the cut) to car catch-ups. The cost of correcting mis in case ofmisrouting due routes often negates the intended th'roughp,ut to catch-ups gain. The determination of hump speed depends on the route pattern selected (distance be tween switches, track layout, etc.), the tag number of the cut (e.g., ,if the current cut goes to the same classification track as the previous cut, the two cuts may be relatively close to each other), and many other speed control and rollability considerations to be determined with inputs from other parts of the yard. Table 4-1 (continued) Routines Input Process Output Generation of Track assignment list From the switch list and track assignment in Pin-puller's list (static) pin-puller's list Switch list structions (an operational management decision or CRT display (dynamic) Post-humping surveillance under the MIS function), a cut list is devel feedback oped. A cut,is determined by the common des tination of contiguous cars and the uppe'r limit on the number of cars allowed in a cut. The pin-puller's list is traditionally in hard-c~py form, with written annotations and modifications. In a more dynamic system the pin-puller's list is a, CRT display, and the sy'stem can accept last minute changes or co'rrections as long as the cars have not passed the pin-puller. The cars' that are not to 'be humped (but will be rerouted) are also displayed. Hump wheel Signals representing The sensing of axle passage over the wheel de- Net count for each wheel detector input passage ofaxie over tectors generates a priority interrupt to the detector processing each sensor PC,computer: The computation of axle count Net car count by direction Time of each passage involves the time of passage of each axle and the elapsed times between axle passage times, as well as the correlation of passage data VI between wheel detectors. Usually two sets of o detectors are placed at the crest to enhance computation (particularly in a bidirectional movement situation) and provide redundancy checks. Hump speed Data from hump wheel This routine is to compute hump speed based on Current hump speed calculation detector processing the passage times of ' the first and second axles routine and the assumed length between axles. Conceptu ally, the hump speed (in feet per second) is the difference between the two axle passage times (in seconds) divided into the wheelbase (in feet). Hump operation Data from hump speed wheel The hump wheel detector process routine gives Updated "as-humped" list display detector processing confirmation that a car has passed, the crest. CRT display routine This information is used in conjunction with Switch list the switch list to establish the identification of the car that has just been humped. As each car passes the wheel detectors, it.s, 11) is re moved from the top of the, CRT display, and the whole CRT page moveS up one line. The purpose of the display is to give visual veri fication of the accuracy of the on-line record. A mistake may occur if the wheel detection routine miscounted the axles or if the switch list is out of sequence relative to the physi cal order of the cars. The ~ars that passed the visual verification go into the "as-humped" file. Table 4-1 (continued) Routines Input Process Output Switch alignment Instruction from hump On occasion the hump engine performs trim opera Control signals to align switches for front-end supervi~or's console tions at the front end of the yard (from the for an area between the crest trim operation Computer flags indicating crest to classification tracks), such as for and a track blocked or locked areas rehumping. The instruction for front-end trim comes from the hump supervisor, and the switch alignment is done automatically for an area, provided the trim operation will not conflict with another protected or blocked area at the time. When the trim operation is com pleted, the hump supervisor releases the area lock, and the switches.go back to automatic routing control. Area trim Instructions from yard Requests may come from the yardmaster or area Switch alignment instructions for protection master or area supervisor supervisor via on-line computer terminals for locking all switches leading into via on-line console performing trim operations in an area (defined the trim area for area protection. by tracks, leads, frogs, etc.). This routine The switches within the trim areas identifies all the switches leading into the are released from automatic control defined area and locks them out from external and turned over to area supervisors control until a release command is issued. for local control. During the area lock, the area is not acces sible to automatic routing or humping. The VI control is given to the area supervisor or foreman for local manual or semiautomatic control. The significance of the area lock to the humping operation is that the locked tracks may necessitate that some cars be rerouted to slough tracks. POSTCREST CONTROL Postcrest wheel Signals from wheel detectors This is a front-end processing routine to reduce Cumulative axle counts for each detector (placed between the crest wheel passages and passage times to axle counts detector processing and the master retarder) and length between axles [based on a measured Passage time of each axle indicating the passage of (or assumed) speed]. To enhance detection re an axle. The input comes liability, two sets of wheel detectors usually into the computer on a are installed (between the crest and the master priority interrupt mode. retarder). This information will be compared with photocell and radar data for validity check. Photocell Photocell beam contact The photocell detects the beginning and the end The determination of the beginning detection routine changes create an inter of a cut (the coupling joints constitute a con and the end of a cut and the rupt to the PC computer tinued state). The passage times of the front sending of a signal to the radar Switch list and end of a cut will help to verify wheel de unit to turn on and off the radar tector data and enhance identification of car Doppler pulse accumulator for car inventory between the .crest and the master re length measurement tarder. The photocell signal also is used to Cut passage times (both front and turn on and off the radar Doppler pulse accumu end) lator for car length measurement. Another Car height category function of the photocell sensor is to detect the height of cars for rollability measurement. Table 4-1 (concluded) Routines ______-=I~n~p~u~t~ ______Process Output Radar detection Radar pulse return The radar Doppler pulse accumulator is turned Cut length measurement of cut length on and off by the photocell's detection routine. Cut length data are calculated and used for speed control and car identification. Determination Wheel detector, routine On a priority interrupt basis, wheel detector Determination of the number of of car axle count information data (axle passage and passage time), photocell axles for each car and length Photocell routine infor data (beginning and end of a cut, coupled cars), between axles mation and radar data (cut length) are checked and Car speed Radar routine information correlated to determine the number of axles for each car. An assumption is made about the standard distances between axles, distance from coupling point to the first set of axles, the maximum number of axles on a car, and so forth. Posthump ,car Output from the determina This routine reconciles car and cut information Updated car and cut identification identification tion of car axle count in the switch list and pin-puller's list with in crest-to-master retarder in and verification routine the sensor-obtained information by confirming ventory file Switch list the number of cars in each cut, car lengths, Pin-puller's list cut lengths, and so forth. In the event of a,discrepancy (may be caused by sensor inac VI curacy or mistakes in pin-pulling), corrective N entries are made to reflect the true tag number of cars. A crest-to-master retarder,car inven tory file ("as-humped list") is'maintained in order of car position and cut configurations. Each car record also contains data on speed control and rollability functions. Weight scale Car axle count and identi The scale (placed after the car ID and speed Enter scale weight to car record routine fication information' sensors) obtains the gross weight of each car in the "as-humped" list for rev Weight of car and, based on other attributes from the car enue and speed control purposes Car record record (car type, capacity, tare weight, length, Initiate rerouting in the event the height), the routine determines whether the car car is overweight is overweight. If so, the car is rerouted. The gross weight of the car is recorded in the car record for ,two purposes: for waybill infor mation under the MIS function and for speed control. Weight Weigh rail reading The weigh rail's function is to classify each Weight category classification to classification car into a weight class (e.g., light, medium, master retarder control heavy) to activate master retarder control. This function is a locally distributed PC function that may be handled by either an analog device or a microprocessor. Its output will go direct- ly to a master, retarder control. It can be viewed as an inner loop of a speed control function (the outer loop being the scale weight routine processed by the PC computer for a more global application). - Axle passage detection from wheel initiates failure-mode actions for a detectors placed after the master possibly impeded PC operation •. retarder. (3) Car location update routine (or car following Velocity reading from exit radar unit. routine) • Output • Input--Car passage information (both entrance and exit) from wheel detectors - Entrance speed. placed before and after the master retarder. - Retarder control command. • Output--Updated car location record - Speed control information to be passed (i.e., change car location from in front on to the next control point. of the master retarder to in back of the master retarder). - Car ID and movement information to be transferred to the next control point. • Processing--Although this is a specific function to update car position records - Failuremes.sages and initiation of from the postcrest zone to the post failure-mode operation (a result of' master retarder zone, the software detection or radar failure). routine should be a generalized yardwide car-following system that moves a car • Processing--The PC computer for retarder record from one zone to another as long control (whether it is for master, group, as the zone boundaries are defined and or tangent) has either a centralized or the car movement information is trans a distributed design. Under a cen mitted to the PC computer. In many tralized design, the mainframe PC yards, the PC computer maintains computer accepts raw input data from individual car records only from the field sensors and then computes and crest to the clear point. Carrecords sends retarder control commands directly for the rest of the yard (receiving to each retarder control. The computa areaL. pullout end, departure area, etc.) tion is based on a global speed control are maintained by the MIS computer. objective function and·the integration of sensor input information from all the (4) Switch logic for conflict avoidance zones and areas under the control of the total PC system. Under a distributed • Input design, each retarder is controlled by a separate PC unit (e.g., an analog con - Wheel detector input to indicate the troller or a microprocessor) that is entrance or exit of a cut. often installed locally at the retarder site. The local PC unit functions as Track and switch layout parameters of the "inner loop" of an overa 11 ·PC track circuits that require special system. Figure 4-2 is a schematic of a attention. typical distributed retarder control system. _. Car -loca tion informa tion on those cars being moved from the crest to the The wheel detectors and radar units classification tracks. provide input to the retarder control system. Besides velocity measures, the - Actual switch position as read by field sensors also provide axle passage roadside equipment. time and count, which are necessary for correlating car passage information with • Output car ID and associated speed control descriptions (weight class, height, - Control signals to switches including length, etc.) as measured during the application of fixed time delays previous PC functions. (i f necessary). The speed 'control logic then determines - Routing error or conflict warning the desired release velocity of the cut messages to flag a potential problem and calculates the control setting of condition. The routing error should the retarder. The actual exit velocity trigger corrective actions in the information is then used for speed automatic routing and car location control functions elsewhere in the yard. software. The master retarder control routine also - Indicator for switch obstruction checks the reliability of the wheel condition when the actual state of the detectors. If the detector is switch differs from the requested determined to be malfunctioning the position. routine generates failure messages and 53 ENTRANCE EXIT WHEEL ENTRANCE EXIT WHEEL DETECTOR .RADAR RADAR DETECTOR ~_\"""'" ~/_-~ RETARDER t----\~ ~/---; \ \1 CONTROL COMMAND RADAR VELOCITY INPUT RADAR LOCAL VELOCITY PROCESS CONTROL INPUT UNIT CAR PASSAGE REQUESTED AND RELEASE VELOCITY VELOCITY DATA YARD PROCESS CONTROL COMPUTER FIGURE 4-2. EXAMPLE OF A DISTRIBUTED RETARDER CONTROL SYSTEM • Processing--This switch logic is to cut, a potential cornering situation forestall any possible car catch-ups or exists. If a collision is preferred conflicts due to limitations of the over cornering, the software routine track/switch configuration, exceptional generates instructions to leave the physical characteristics of cars, or switch unchanged for a safety margin abnormal speed dynamics that may result time delay after the passage of the in collisons, cornering conflicts, or first cut at the switch point. derailment. Although described in this section, these logical routines are - Car Stall--The stalling of a cut after applicable at almost any area from the a switch may cause a cornering master retarder to the coupling point. accident if the switch is thrown and a The potential conflict situations and second car passes. In this situation, the methods of solving them differ from a logic may be chosen to leave the yard to yard. The following are SOme switch open to the track circuit of examples of these situations: the first cut and divert subsequent traffic from arriving by properly - Car Catch-up--A catch-up condition adjusting upstream switch settings. develops when a successor cut enters a switch track circuit before the Short Track Circuit--When a car is predecessor cut clears the circuit. much longer than a switch track If the second cut does not share the circuit (e.g., the track circuit is 60 same switch setting as the first, it feet long and a car is 100 feet long), ends in the wrong track circuit and a the switch must not b~ thrown until routing error therefore exists. the car completely clears the track Corrective entries are generated for . circuit. the subsequent routing plan of the misrouted cut. Also, the car-location - Multiswitch Zone--Certain zones are record must reflect this error. defined by more than a single switch. This is very prevalent when two or - Cornering Conflict--If the distance more switches are very close and they between two consecutive cuts at a must be thrown in tandem to safely branching point is very close and the route a cut. In this case, the switch velocity of the second cut is suf logic generates a special control ficiently great relative to the first command for the zone (or zones) affected. 54 - Check Switch--The switch software also position of the cars is used to update verifies the actual switch position car inventory and car location records. after a switch ch'ange command has been The stop position can also be estimated given. If the state is not changed as using a distance-to-couple track circuit requested, adjustment entries must be (Section 4.1.2.2). made, until the obstruction is removed. 4.2.8 Pull-out End 4.2.6 Group Retarde~ to Tangent Retarder (1) Exit (skate) retarder control The software routines governing the area from the group retarder to the tangent retarder are • Input very similar to those in the other areas. The differences are mostly in the physical charac - Input from lock-unlock routine. teristics of the switch/track layout, speed control parameters, and the input fidelity of - Detection input from track circuit to field 'sensors. The software routine for group, indicate the exit of last car in a retarder control can be viewed as identical to pullout operation. that for master retarder control--the type of wheel counting devices; velocity measurement • Output--"Open" command to exit retarder. devices, and retarder PC functions are the The retarder is normally closed. same. The car-following routine (to move the car record from zone to zone) and switch logic • Processing--The skate retarder is routines also are the same for this area. usually closed. It opens during the pullout operation (when the track is 4.2.7 Tangent Retarder to Coupling Point locked from the crest end) and closes after the last car clears the track The retarder control, car counting and location circuit. updating, and switch control of the tangent retarder to coupling point area are similar to (2) Track lock-unlock routine those for the other areas. The principal differences are in the switch/track layout • Input geometry and the characteristics of field sensors (e.g., the number of wheel detectors or - Request from hump supervisor the number of radar units). The only major additional control function in this PC area is Exit retarder open indicator the detection of car movement and car stop location., The car movement detection routine is Alarm condition indicator briefly described as follows: - Car movement data. • Input • Output - Move or no-move input from track space equipment. - Track lock instructions for switches - Car ID and previous speed control data. - Track unlock instructions for switches. • Output • Processing--Except under alarm condi tions in the yard, most of the locking - position of car stoppage and unlocking instructions are results of humping or pullout operations. The - Coupling velocity of each car processing is mainly generated by a request from the area supervisors or - Track occupancy estimate. the hump supervisor. • Processing--After a cut passes through 4.3 LEVEL OF AUTOMATION the tangent retarder section, the PC system must know where it. stops on the Although fully automated proces~ control is the track. This can usually be detected by de facto standard for new and recently upgraded using track space equipment for motion classification yards, PC systems vary greatly or no-motion indications. The changing from yard to yard. The major determining fac consecutive space readings imply the tors in these variations are economic considera motion of a cut from one section of the tions, present and anticipated throughput, and track to the next. A constant state the age* of the yard. Significant variations among two or more consecutive space. readings indicates a stoppage of the cut. The speed with which these *In new yards with high traffic volume, a fully readings are changed forms the basis for automated system may have been installed. In estimating coupling velocity, which is older yards that have been upgraded, often a used for the calibration of speed combination of manual, semiaut~matic, and control parameters upstream. The stop automatic operations is found. 55 based on the level of automation include: With manual retarder control. a ,retarder opera semiautomatic switching/manual retarding and tor. located in a building alongside the re semiautomatic switching/automatic retarding. tarders. manually controls the retarder force and the duration of the force. He uses his The semiautomatic switching system is known as a experience, observes the car's rolling behavior. relay system. Pushing a track destination but and considers the type and often the weight of ton (or buttons) sends a destination code to cars .in determining his control ,action. switching circuits. which align switches for the cut as it proceeds to its assigned classifica With semiautomatic switching/automatic retarding, tion track. A certain number {usually four or one computer is used to route cars and produce five) of track destinations can be stored at one fixed exit speeds from retarders. The engine time in the storage unit in the hump conductor's foreman, rather than the computer, has the switch office; additional relay storage units are in list. When his train is ready to be classified, front of lap and individual switches. Switch the engine foreman goes to a control console in repeater relays route the destination code of the hump tower and punches in the classification each cut to the next appropriate storage unit track assignment for each cut as it approaches (the one in front of the next switch to be the crest using destination codes obtained from thrown) as the cut shunts the track circuit the switch list. preceding each switch along its route. As each "' cut's destination code is transferred from the In this type of system, the computer systems :' fir.t relay storage unit (in the hump conduc automatically control the retarders. tor's office) to the next storage unit. the hump conductor may enter the destination of another cut (GRS. 1957). 56 CHAPTER 5: SYSTEM DESIGN This chapter describes· analysis methods for MISs in most cases are designed and installed by systems design in railroad classification the railroad itself, with perhaps the assistance yards. The goals of systems design are to of consultants and vendors. The design and analyze yard requirements, design alternative specification of the system must therefore be solutions, select feasible options, and define completed in much greater detail than is re functional and hardware specifications. The quired for a PC system. Functional specifica implementation following system design is tions must be further refined into a detailed discussed in Chapter 6. software design specification. This document is eventually used in program design and coding. Because process control (PC) systems and manage The hardware study results in a detailed hardware ment information systems (MISs) have different specification document, which is used as part of purposes and end goals, their designs also dif the request for proposals (RFP) sent to hardware fer. The PC application has traditionally been vendors and is used for the design of acceptance considered reasonably straightforward, and be specification and testing. Test plans and imple cause of the problem of interfacing with yard mentation schedules must also be completed in field hardware (e.g., scales, switches, re detail. tarders, track circuits), its design has most often been left to the signal manufacturers or The design of the yard computer system is divided systems vendor with little design effort by the into four steps: the survey phase, analysis yard. (The most notable exception is Santa Fe's phase, software design phase, and the hardware designing of the PC equipment at Barstow Yard.) study. Figure 5-1 indicates the relationship In analyzing process control, railroad designers between these steps. The design cycle need not gain a concrete idea of their own requirements proceed step by step; tasks may overlap or be before approaching a system manufacturer. Having completed concurrently. The concept of a struc a detailed functional specification, a prelimi tured systems design is one of the many popular nary design, and an estUnate of hardware require systems analysis techniques used. Others in ments, the railroad can better specify the system clude the BIAIT, BSP, PSL/PSA, and SADT methods required from a turnkey vendor. Thus, the (Townsend, 1980). Structured design stresses vendor/supplier need not do preliminary design the use of graphic tools to represent functions work. In the end, both railroad and supplier of the computer system (Page-Jones, 1980; benefit from a better system design that meets Yourdan, 1978; Auerbach, 1979). In each phase of the actual needs of the yard. the des~gn, the computer system is partit~oned PHYSICAL CONSTRAINTS MANAGEMENT HARDWARE SPECIFICATION PROBLEM DEFINITION AND CONSTRAINTS BUDGET AND SCHEDULE SOFTWARE SPECIFICATION PERFORMANCE '------~REQUIREMENTS USER DESCRIPTION OF CURRENT OPERATIONS AND USER REQUIREMENTS FIGURE 5-1. SYSTEM DESIGN CYCLE 57 and data. flow diagrams are used to represent, in The entire "project" team ch~nges in size and com a simplifiedfo~, input, outP~t, and function. position during ,the project life. cycle. From the development of software ,and har.dware speci 5.1 SURVEY PHASE fications to software development .. and testing, the number of EDP personnel grows, and then In the survey phase or feasibility study, yard usually tapers off as the, acceptance test and engineers explore alternative procedures and systems installation point is reached.· Concur equipment to decide whether the likely benefits rently, the user involvement increases. justify the expense of the changes to be made. Constraints. from management will structure the 5.1.2 Development and Implementation scope, budget, and schedule of the project. A Planning and Scheduling preliminary staffing plan (Section 5.1.1) and . , preliminary schedule (Section 5.1.2) are also After the project team has., been organized, it established. These are revised throughout the must" specify the tasks. to be performed during analysis phase. Discussions with knowledgeable development and implementation and prepare a users provide a description of the environment checklist of tasks. The task list depends on and its problems. The feasibility study pro the type of system to be implemented, but the vides a guide for systems design and includes: basic activities are the.following: (Hartman, 1968) • Complete feasibility study. • Management recommendations, goals, and a descript10n of project charges. • Complete systems design. • A general description of the • Develop hardware and software organization. specifications. • A summary of requirements, objectives, • Develop acceptance test plan and tests. constraints, and current problems. • Complete procurement process., including • Overall project schedule including any benchmark testing required for project team staffing and project vendor selection. delivery date goals. • Develop and test software. 5.1.1 Organization Planning and Staffing • Prepare system documentation. The organization of the systems project team depends on a number of factors, such as: the • Train users. size and complexity of the proposed system, whether it is to be completely new or a modifica • Prepare site preparation plan. tion of an existing system; whether the computer system configuration is to be decentralized, • Convert to new system. regionalized, or centralized; and whether the development responsibility is centralized or • Run acceptance test and install system. within the yard. Nonetheless, the first step in planning and staffing any systems project team The task list should include not only the is to select the project manager. The manager, prescribed activities, but also a realistic in turn, selects personnel from both the EDP evaluation of the time required to perform each department and other departments or divisions. activity (both in terms of calendar days and person-days of work) and the name or title of Project leaders are usually chosen from within the person who will be responsibile for the the EDP department for MISs, but they may be activity. chosen from the signal department for PC systems. Project teams include people with expertise in The implementation and installation cycles for systems design, systems software, data base man MISs and PC systems in most cases are different agement and design, and operations. User repre because,PC systems are less likely to be fully sentatives for the team are 'chosen from other developed in-house. Usually, only larger departments and from each yard if a centralized railroads have the in-house expertise required or regionalized system is planned. Representa to develop specialized hardware and software. tives should be at least at the supervisory level Therefore, PC systems are usually purchased as a and have a thorough knowledge of the operations package from an independent vendor. that will be incorporated into the new system. In PC system, for example, the yardmaster is Because most railroads have some degree of MIS likely to'be included on the team to provide capability, most yard,MIS computer systems will information on and ideas for system design and be an upgrade of an exis'ting system or they must specifications. User representatives not only link to a centralized systemwide MIS computer. become members of the project team, but also The development cycle of an MIS upgrade is the assign operating personnel under their super same as that for a new system but must take into vision to work with members of the project team, account interface and conversion details in the as required. hardware study, acceptance test, and implemen tation stages. 58 PC system development requires organization plan After the task list has been completed, the pro ning and staffing, implementation scheduling, and ject team ,prepares a preliminary PERT diagram, the development of functional specifications. In critical path diagram, or other project control many cases, detailed design need not be carried charts showing elapsed times and start and com further because final design is often a task of pletion dates for all the specified activities. the vendor. The remainder of the project in This ensures that all necessary activities are volves procurement~ design monitoring, user performed in the proper sequence and on time. training, and site preparation. After the critical path and total project time are known, iterations of the chart will probably The case study at Potomac Yard involved the pro be made to adjust the time frame', by changing curement of PC hardware and software and the schedules or manpower assignments. Figure 5-3 development of additional MIS software, but it is an example of the critical path diagram from required no additional MIS hardware. Therefore, the case study. as Figure 5-2 indicates, software changes were scheduled to begin iamediately. If additional 5.2 ANALYSIS PHASE HIS hardware had been required, it would have had to be installed before software coding began. The analysis phase further defines the project This is because existing systems are often too within the goals specified previously in the small for development or incompatible with the feaaibility document or project charter. Users replacement hardware and operating system. provide additional information on the'present o 2 4 6 8 9 10 11 12 13 14 IS 16 17 18 19 20 21 COMMON PROCEDURES ORGANIZATION PLANNING AND STAFFING • • SYSTEM DOCUMENTATION • DETAILED IMPLEMENTATION SCHEDULE • • • USER TRAINING • ECONOMIC JUSTIFICATION FUNCTIONAL SPECIFICATION ~. .------~.~ -..-----~.~ MANAGEMENT INFORMATION SYSTEM SYSTEM DESIGN SOFTWARE DEVELOPMENT. ON·LINE TO ALL TENANTS REAL·TlME INVENTORY SPECIFICATIONS TESTING. AND INSTALLATION ~..------~.~ ~..------~.~ • • • • PROCESS CONTROL SYSTEM GATHER ADDITIONAL INFORMATION FROM PC VENDORS PROCUREMENT PROCESS SYSTEM DESIGN BY VENDOR • • ...... ------~.~ ------ACCEPTANCE DEVELOP TEST DESIGN OPERATIONAL PROCEDURES • • • • SITE PREPARATION INSTALLATION Note: The .cele glve. an ,"Imlte of rhe 11m, required 'or the call Iludy prolect Implementation cycle. . ' O.her ",oloe'. will VI", ,Ignlliclnlly. - FIGURE 5-2. IMPLEMENTATION CYCLE 59 The goal of the analysis phase is to document in a, readable and, understandable form the functions and goals of the new system. The analysis pro vides both a link between user needs and the design of changes to me~t these needs. In addition, the analysis provides predictions of benefits, scheduling, and performance character istics. The functional specification is used to communicate the system design to both users and management. The goal is to produce a design that is compliant with both users' needs and management's, constraints. The functional speci fication should be sufficiently comprehensive to use during implementation to evaluate the suc cessful completion' of system goals. To remain valuable in later phases of the software design EVENT cycle and in the implementation and installation NUMBERS ACTIVITY cycle, the functionaf specification and docu ments that evolve from it must be easy to modify 1 - 2 Direct communications to each tenant railroad 1 - 3 Organization planning and staffing as required from user feedback and changes in 1 - 4 Gather additional information from PC vendors overall goals and constraints. In general, 2 - 7 MIS real-lime inventory because functional specifications depict only 3 - 4 Detailed implementation schedule 4 - S Economic justification study the logical flaw of the system, they should be 5 - 6 Functional specifications unaffected by changes in hardware, vendors, and 5 -13 System documentation operational personnel. ' 6- B PC procurement process 7 - 9 MIS system design specifications B -10 Develop PC operational procedures 5.2.1 Assessment of Current System B - 11 PC system design bv vendor 8 -12 PC ilcceptence test design 9 -12 MIS software development, testing, and installation The first step in the analysis phase of systems 10-12 MIS and PC lIser training design is to learn about the current system and 11 -12 PC site preparation 12 - 13 PC installation its environment. The analysis of current pro cedures is used to create a model of current functions without regard to expected changes in FIGURE 5·3. SAMPLE CRITICAL PATH DIAGRAM the yard environment and functions performed. The volume of current and expected yard traffic system, and the project team explores the feasi influences eventual hardware and software design. bility of alternative methods to implement Information on the current hardware directly re changes and decides which ones to pursue. A des lates to the hardware study. Railroad and yard cription of the recommended system is produced as objectives, management structure, and institu a functional specification. tional considerations are not quantifiable but influence the design and selection of system In the analysis phase, the project team develops des i gn options. Data on cu'rrent cos ts are used a preliminary hardware configuration design. ih the cost/benefit analysis. This is used for cost/benefit estimates but, more important, it becomes the basis for the hardware The structured analysis method relies on data study. Additional configurations and perfor flow diagrams to model the current physical data mance details are developed in the software flow. For example, current clerical operations design phas'e. can be diagramed on the basis of the movement of waybills, as shown in Figure 5-5. Additional Structured analysis is used for analyzing user data on the physical environment are also requirements, seiecting a system that best pro gathered as part of the current system'model. vides solutions, and documenting a structured Data such as current traffic distribution, yard description of the system. Figure 5-4 illus layout, and hump speed are required for the PC trates the seven steps of structured analysis: spec ification. (1) model current system, (2) derive logical equivalent, (3) model new logical system, (4) The operation of all areas of the yard that may develop alternative functional configurations, affect the eventual computer system must be (5) measure costs and benefits, (6) select best examined and documented. 'Areas examined include option, and (7) package results as a structured clerical procedures, present computer and com functional specification. The results of the munication systems, communication within the analysis phase include the structured functional yard, communication outside the yard, inventory specification and guidelines for hardware re control and record systems, ma~agement reporting, quirements. Other results may be: a tentative yard traffic volumes, classification procedures, ., equiPment configuration, a performance document, current automatic car control in the yard, cur a tentative design, an RFP (depending on detail rent yard layout, and the current track hardware. required), file and data layouts, resource anal ysis (disk and main memory), and more detailed 5.2.1.1 Information Gathering. The gathering project scheduling and personnel planning. This of information on a classification yard may be information is needed for budget and scheduling organized in terms of system functions. The estimates for management. description and volume of the functions of yard 60 COST ESTIMATES DESCRIPTION OF FROM HARDWARE STUDY CURRENT OPERATIONS OPTIONS REVISED BUDGET AND SCHEDULE NEW LOGICAL MODEL CURRENT LOGICAL MODEL PHYSICAL REQUIREMENTS SELECTED OPTION FUNCTIONAL SPECI FICA TlONS FIGURE 5-4. STRUCTURED ANALYSIS STEPS INSPECTION CLOSEOUT REPORT SHEET 5.0 r-2.0. 4.0, EXCEED SHOP WIB PICKOUTS 5.0 CONSIST REPORT 'Z.. ~'Z. ADVANCE REVISED ARRIVAL CONSIST SWITCH LIST DEPARTURE 1.0 2,0 3.0 4.0 5,0 7.0 RECEIVING ~WIB AGENCY WIB CLASSIF· W/B_ KEYPUNCHING WIB- GENERAL WIB CREW YARD ICATION OFFICE CLERK CLERK CLERK 5.0 4- f.6.0 -7.0 PICKOUTS SWITCH LIST CARDS CONSIST REPORT ~5,0 "3,0 PICKOUTS RELEASE SHOPI EXCEED W/B FIGURE 5-5. FLOW DIAGRAM OF WAYBILL PROCEDURES FROM CASE STUDY YARD 61 inventory and PC systems are used to design COMPUTER models of both the current and future computer MIS PC FUNCTIONS systems. The functional model of the yard Inwntory Humping Speed Reliability evolves into the functional specifications used Structure Control Rnpon. Volume Time in software design. The volume descriptions are Quantlflars used to determine file requirements and the size ~ Number of can X of hardware components in the hardware study. Hump rota X X X Report Yard volume quantifiers may define: (1) a frequancy X X physical attribute, such as the number of tracks Volume of and their lengths; (2) a car processing volume, Inqulrla. X X such as distribution of arrivals; or (3) the size of a specific computer function, such as reporting frequency. Each function is described FIGURE 5-6. SAMPLE MATRIX OF FUNCTIONS AND QUANTIFIERS by a number of the numerical quantifiers. Each FOR STRUCTURED ANALYSIS quantifier, in turn, may affect a number of func tions. For example, the average number of cars alternative yard scenarios are of different sizes humped as a train is a quantifier for the hump or traffic volumes, for example, quantitative control function, and it also affects the switch values are scaled to reflect these differences. list generation function, the PC-to~IS communi cations function, and the yard inventory update Once quantitative data have been sathered, flow function. A matrix of functions and quantifiers, charts can be used to document the current proce such as that represented in Figure 5-6, provides, dures in th·e yard. These represent the sequence in terms of discrete data, a complete description in which a person or machine completes a series of the yard, including interrelationships between of functions. Each flowchart contains a number each function. of boxes representing func~ions, with arrows between each function to represent the physical With the matrix structure, data can be gathered relationships and data flows between functions. systematically, independent of interrelation Figures 5-7 and 5-5 present examples the current ships. Functional descriptions and numerical operations documented in the case study of Poto data are gathered on the current situation and mac Yard. For each person or machine, a more are developed for. one or more hypo.thetical detailed description of the internal process must alternatives from the feasibility study. If be documented. Exhibit 5-1 details the current 5.0 GENERAL OFFICE CLERK 60 COMPUTER INBOUND ADVANCE CONSIST TRAIN SHEET INBOUNDI INTERCHANGE AND 4.0 CARD S INTERCHANGE ARRIVAL REPORTS HAZARDO US COMMODITY 14---PRINTOUT r- - - -- I----REVISED SWITCH LIST YARD UPDATE f---.--- RADIOITE LEPHONE TRACK UPDATE 14___ NOTIFY G ENERAL OFFICE C LERK - - --- 1-----CLOSEOU T SHEET OUTBOUNDI 104--- CAR LIST ADVANCE ADVANCE CONSIST CONSIST 104--- OUTBOUN o TRAIN SHEET - - - -- INQUIRY TERMINA L SHOP REPORTS TERMINAL/PRINTER MIS REPORTS ·R.I.r to Figur. 5-6. FIGURE 5-7. CURRENT COMPUTER PROGRAMS AT CASE STUDY YARD 62 EXHIBIT 5-1 CURRENT MIS PROGRAMS AT CASE STUDY YARD_ Inbound (cars' enter' inventory) INQUIRY (c?ncluded) Reads RFPCOMFlLE; one record per car, once INQUIRY Files Accessed Sort per train ' Creates MASTERFILE (200 characters, 4/block) Return routing Builds CLlNVFILE; contains lO, loaded/empty By line MASTERFILE, By 10 and (L/E) ststus, weight, block numbe'r, and latest listing CARRECFILE, tenant track number (11 characters, 45/block) 60DAYFILE line Creates statistical record Produces inbound train sheet Dangerous cars FLAGFILE Last event ,Interchange reporting to RFPCOMFlLE (dis play CLlNVFILE For all last hump, 10, dangerous Yard Update' ,(inventory change from hump,ing) track number, loads ' block number, L/E) Inventory re'cords moved to WORKFILE, deleted in CLINVFILE 'Four-hour report--' FLAG FILE Last event Cu tof fs en tered by line CLlNVFILE By tenant WORKFILE updates CLINVFlLE, deleted in (display last hump, line and WORKFILE L/E for each block, block num Move recorded in MASTERFlLE total per line) ber NEWYARDM records, movement in CARRECFILB Per diem FLAGFILE Last event Track Update (i~ventory change) (display lO, CLINVFILE By block block number, number Records in-y~rdmovement on CLINVFlLE 'and track number, MASTERFlLE L/E of specific Reports shop move'ments to RSICFlLE block of cars) Outbound' (cars' leave inventory) Track inventory- FLAGFILE Last event by yard and CLINV FILE By track Updates STATISFlLE track (dis play number Updates CARRECFILE last hump, L/E/wt Reads CLlNVFILE to OUTFlLE, deletes CLINVFlLE totals) Moves consist information to RFPCOMFlLE or cards Track inventory- FLAGFILE Last event Prints outbound train sheet by yard and track CLINVFILE By track NCRINSET moves MASTERFlLE to CARRECFlLE (display last number hlDDp, L/E/wt (read ' Interchange (create interchange report) totals, listing twice) of lO, LE, Input of day/month block, track) MASTERFlLE and CARREDFILE read to create ICFILE Track inventory-- FLAGFILE Last event Information to tenant lines via RFPCOMFlLE by yard CLINVFILE One yard or cards (display last Daily or monthly reports printed hump, number and weight totals, num- MIS REPORTS ber and weight of cutoffs by block) File Frequency Track inventory-- FLAGFILE Last event STATISFILE by track CLINVFILE By track Trains received and forwarded Daily (display last number Cars handled Daily hump, L/E/wt In/outbound train statistics Daily totals first and In/outbound train statistics Monthly last car's 10, Statistics to Richmond Monthly L/E, block, track) FLAGFILE Tonnage report- FLAGFILE Last event SCL load count Monthly by outbound CLINVFILE By block B&O, CONRAIL tonnage Monthly train (display number last hump, number INQUIRY of cars track number, ,block num INQUIRY Files Accessed Sort ber, and tota I weight for specific Car status blocks and totals Current MASTERFILE and/or By lO for train) All history CARRECFlLE Car status with waybill Current MASTERFILE and/or By lO All history CARRECFILE 63 Potomac Yard MIS computer programs. Another Functions in the yard can be grouped into sub example of a flowchart of yard operations is systems of similar functions. An example from Figure 5-8. Exhibit 5-2 provides details for the Potomac Yard case study is the yard inventory this example. subsystem. Figure 5-9 shows the relationships 0.0 0.0 ...----...1 TELECOMMUNICATIONS EMPTY CAR DISPOSITION 1.0 RECEIVING YARD CLERK WAYBILLS 2.0 WAYBILLS PICKOUT AGENCY WAYBILLS DEPARTMENT EXCEED AND 3.0 SHOP CLASSIFI· CATION CLERKS 4.0 GENERAL 4.11 CLEAR 4.2 MAINTAIN 4.3 ASSEMBLE 4.4 OUTBOUND OFFICE SHOP/EXCEED WAYBILL OUTBOUND 'PROCESSING CLERK WAYBILLS INVENTORY PAPERWORK CONSIST REPORT OUTBOUND dr=!' TRAIN SHEET :: OUTBOUND TRAIN SHEET ~------~ 5.0 CREW CLERK FIGURE 5-8. FLOWCHART OF FUTURE CLERICAL OPERATIONS AT CASE STUDY YARD 64 EXHIBIT 5-2 DETAILED PROCEDURES FOR NEW PAPERWORK PROCESSING AT CASE STUDY YARD 0.0 Telecommunications 4.0 General Office Clerk 0.0 Empty car disposition 4.1 Clear shop and exceed waybills In: Advance consists In: Shop car report Empty car disposition Height clearance Do: Create consist file Waybills from 4.2 Update destination from empty Do: Release shop and exceed height car disposition waybills for classification Out: Advance consist to 3.1. Out: Waybills to 3.3 4.2 Maintain Waybill Inventory 1.0 Receiving Yard Clerk In: Waybills from 3.1 and 3.3 1.0 Ani val Track update report printout In: Train arrival paperwork Humping report printout Do: Train arrives, route waybills to Do: Waybills are sorted and filed in agency track-standing order Out: Waybills to 2.0 Waybills are pulled for classi fication and departure 2.0 Agency Department Out: Shop and exceed waybills to 4.1 2.0 Routing Departure waybills to 4.3 In: Waybills from 1.0 4.3 Assemble Outbound Paperwork Do: Check routing, photocopy, and In: Closeout sheet from trainmaster forward pickout requests Car list printout Out: Waybills to 3.1 Hazardous commodity printout pickout waybills to 4.3 from 3.2 Waybills from 4.2 3.0 Classification Department pickout waybills from 2.0 3.1 Update consist records Consist report printout from 4.4 In: Waybills from 2.0 Do: Pull departing waybills" Videotape of arriving train Assemble waybills and hazardous Inspection report commodity printouts, outbound Advance consist train sheet, and consist reports Do: Check consist against videotape Out: Assemble paperwork to 5.0 Update consist from waybills 4.4 Outbound Processing Update consist class/status from Do: Prepare consist report and out inspection report bound train sheet using CRT Update waybill from empty car terminal disposition Out: Outbound train sheet printout Out: Waybills to 4.2 to 4.3 3.2 Inbound Consist report printout to 4.3 Do: Enter arrival information to in bound train 5.0 Crew Clerk Out: Hazardous commodity printout 5.0 Departure to 4.3 In: Outbound train sheet from 4.3 3.3 Classification Consist report from 4.3 In: Preliminary classification guide Waybills "from 4.3 Exceed and shop waybills from 4.1 Hazardous commodity printouts Do: Verify classification guide using from 4.3 CRT terminal Do: Log information in outbound log Out: Waybills to 4.2 book Out: Paperwork to departing crew *Refer to Figure 5-8. between various functions. Figure 5-10 shows in 5.2.1.2 Current Level of Automation. A complete more detail the input and output and relationship survey should be conducted of the current hard between MIS functions, programs, and files. An ware, software, and communications equipment used overview can be drawn, as in Figure 5-11, to show in the yard and any hardware with which new yard the interrelationships of subsystems within the hardware would interface. This list should in total system. For each flowchart, detailed clude for each item of hardware a complete des information gathered [software programs, file cription, original cost, expected time of re sizes, and information flow (data dictionary), placement, replacement cost, and space, power, and the frequency of each function] should be and environmental requirements. EDP personnel identified and listed in a separate document. should be contacted about which hardware compon The logical processes of each function and the ents are irreplaceable because of custom design. format of all input (communication, keyed en Figure 5-12 is an example of a system configura tries, cards) and all output (reports, screens tion from the case study. for inquiries) should also be documented. 65 r INVENTORY UPDATE TERMINAL RADIO [ CONSISTS rTERMINAL INPUT ~_ (FROM PCI r OR TELEPHONE INBOUND YARD UPDATE TRACK UPDATE OUTBOUND r-HAZARDOUS COMMODITY (PI LHUMPING REPORT (PI LTRACK UPDATE (PI r-CONSISTS (TO COMMI L-. ARRIVAL/INTERCHANGE r-0UTBOUND ~ REPORT (TO COMMI TRAIN SHEET (PI L..,. CONSIST REPORT (PI r REHUMPING I r TERMINAL INPUT INVENTORY INOUIRY AND CLASSIFICATION -- UPDATE MIS REPORTS LCLASSIFICATION r- TERMINAL OR PRINTER GUI DE (TO PCI L...- CAR LIST INVENTORY FILES Note. (PI, Printed Output IPCI, Process Control System COMM, Communications Subsystem FIGURE 5-9. YARD INVENTORY SUBSYSTEM AT CASE STUDY YARD 5.2.1.3 Physical Attributes of the Yard. A com charge of management made in the feasibility plete study of the yard must include data on study. Figure 5-14 depicts the functional traffic, yard layout, and current field equip (logical) model of the upgraded yard information ment. Traffic data should comprise arrival and control systems in the case study. No schedules and mix of cars, number, type, and assumptions of hardware are made when developing frequency of moves within the yard, and depar the logical model. Figure 5-11 presents the ture schedules and mix of cars. For the yard functional grouping (partition) used in the case layout description, the project team should pre study to design hardware alternatives. The pare a track diagram, specify track capacity, and logical interface between subsystems indicate formulate a detailed list of all field 'hardware. how the physical systems will communicate. Current humping rates and crew schedules should be computed. In the structured analysis method, a complete description of each logical system includes data 5.2.2 Develop Functional Model of the New System flow diagrams and a data dictionary. The data dictionary lists all files and the specific data The first step in modeling the new system is to required at each interface and describes the define a logical (functional) equivalent to the process involved in each step in the data flow current physical syst~m. The actual tasks are diagram. This description is the basis for the generalized to represent the underlying goal. To eventual functional specification. represent the logical equivalent of the physical data flow, only functions of the yard and their In many cases, one functional model may not be interfaces are represented using a data flow dia adequate because the level of sophistication and gram. The representation is independent of scope of functions may not yet be well defined. physical hardware. Figure 5-13 is a simple data The feasibility study may have indicated a number flow diagram from the case study. of options to be analyzed. The choice between options is made as more comparative information The abstract representation of the current-system is available after the cost-benefit study (Step is then used to develop a similar representation 5). of the new system. Requirements and goals of the new system are added as functions of the new To fully develop alternatives, the project team logical model. This new model must meet the must define the functional requirements for the 66 YARD INVENTORY SUBSYSTEM FILES AND INPUT/OUTPUT PROGRAMS PROGRAM CALLS INVENTORY UPDATE PROGRAM HAZARDOUS COMMODITY (P) (4.3) INBOUND CONSIST FILE ARRIVAL/INTERCHANGE CLASSIFICATION REP,ORT to COMFILE CLERK 13.2) MASTER FilE STATISTICS FILE CLASSIFICATION GUIDE (TO PC) CLASSIFICATION INVENTORY FilE VERIFICATION BY CLASSIFICATION . CLER K (3.3) YARD UPDATE OUTBOUND PROGRAM (FROM PC) INBOUND PROGRAM YARD TERMINALS INVENTORY ...-___ [MASTER FILE UPDATE HUMPING AND TRACK CAR RECORD FilE UPDATE REPORTS (PI (4.2) INVENTORY FilE INVENTORY UPOATE PROGRAM GENERAL OFFICE CLERK (4.4) MASTER FILE OUTBOUND TRAIN SHEET OUTBOUND INVENTORY FILE (P) 14.3) CONSIST REPORT STATISTICS FilE (PI (4.3) CAR RECORD FILE ADVANCE CONSIST TO COMFllE - INVENTORY FILE MASTER FILE TERMINALS INQUIRY AND MIS REPORTS ....,...-.---1 CAR RECORD FilE PRINTERS STATISTICS FILE - FIGURE 5·10. NEW MANAGEMENT INFORMATION SYSTEM PROGRAMS AT CASE STUDY YARD 67 COMMUNICATIONS SUBSYSTEM upgraded yard. General guidelines should be a by-product of the original feasibility study. FILES AND If further clarification iorequired, the project INPUT/OUTPUT PROGRAMS PROGRAM CALLS team members must intervi~1 both users and man agement. This approach, however, most likely CLASSIFICATION ADVANCE CONSISTS will produce ambiguous results requiring a CLERK (3.1): CONSIST (COMFI LE/TENANTS) number of different functional alternatives. PROCESSING ADVANCE' CONSIST FILE Described below are some alternative MIS CONSIST (3.1)' functions. INSPECTIONi REPORT (3.1): The purpose of the yard MIS" is to provide better and more timely information so as to enhance operational efficiency. Its function can be TENANT subdivided into two groups: (1) those that pri TENANTI COMMUNICATION , COMFILE RAILROADS' AND TRANSLATION I marily benefit system central data processing and (2) those that benefit the local yard. How ever, policies and procedures regarding the division of responsibility between central and" local 'differ "from one railroad to another; a clear-cut grouping scheme is therefore not pos EMPTY CAR COMFILE/TENANTS sible. Exhibit 5-3 depicts a division into DISPOSITION INQUIRY [CONSIST FILE (0.0) systemwide MIS, yard MIS, and PC functions. Discussions in the design manual should be limited to local yard functions and their relationship to central systemwide functions. Section 5.2.3 discusses the distribution of TERMINALS' functions between central and yard locations. TERMINAL MIS REPORTS (PI' COMFILE COMMUNICATION INSPECTION REPORT: 5.2.2.1 Communication. The communications function is to take information from yard com puters and transmit it to "the systemwide MIS Note: (P) = Printed Output; (PCI = Proce •• Control System; all number. in ( I rafar computer. Some yards, such as Potomac Yard, may to Figure S.a. have more than one systemwide MIS computer. At Potomac Yard, the MIS computer must communicate FIGURE 5-10. (Concluded) with the computers of six different railroads. TERMINAL TERMINAL FIELD SENSORS INPUT INPUT INVENTORY ARRIVAL! INTERCHANGE PROCESS UPDATE YARD REPORT CONTROL INVENTORY COMMUNICATION COMPUTER SUBSYSTEM OUTBOUND SUBSYSTEM DISTANCE TO CONSIST COUPLE RECORDS SWITCH INBOUND CONSIST ADVANCE -{ LIST RECORDS CONSISTS EMPTY CAR HUMPING REPORT FIELD EQUIPMENT INQUIRIES TRACK UPDATE REPORT TENANT RAILROADS TERMINAL AND PRINTER OUTPUT HAZARDOUS COMMODITY PRINTOUT OUTBOUND TRAIN SHEET CONSIST REPORT FIGURE 5-11. SYSTEM INTERFACES 68 DISK DISK PRINT DRIVE DRIVE ER NO,3 NO,4 BATCH ....______OPERATOR·S ______--t COMMUNICATIONS CONSOLE ----I CONSOLE CPU CONSOLE CPU (BI (AI DIRECT COMMUNICATIONS LINK INQUIRY INQUIRY INQUIRY LINE CRT CRT CRT CRT CRT TENANT COMMUNICATIONS TERMINAL TERMINAL TERMINAL PRINTER TERMINAL TERMINAL TERMINAL TERMINAL TERMINAL FIGURE 5-12, SAMPLE HARDWARE CONFIGURATION FROM CASE STUDY YARD MOVEMENT TRAIN IN YARD CALLED INCOMING CAR PAPERWORK OUTGOING t---_CAR PAPERWORK FIGURE 5-13, SAMPLE DATA FLOW DIAGRAM OF CURRENT OPERATIONS FROM CASE STUDY YARD The method of telecommunication must also be of arrival and departure reports to the system established. Existing communications may be by wide computer or other yards is required. The telephone or by teletype, but new functions may number of reports will correspond to the expected require direct communications or communications number of trains arriving and departing. to an intelligent terminal that keypunches the required information onto punched cards. System If' advance consists must be. sent and received, wide reporting requirements for consists, in the expected volume must be estimated. If con quiries, and interchange reports are used to sist information is often inaccurate, it cannot estimate the volume of messages and the frequency be used for the planning of yard operations until and size of the messages. Sometimes, the two it is verified by the arriving train. The size communications computers will not use the same of the consist record for each car influences format, symbols, or abbreviations. In that the communications load. case, the communications function must also translate some of the messages, which requires Through inbound processing, the arrival of a both additional processing power and the storage train is recorded, and its individual cars are of translation tables. The capacity of the com entered into the inventory. To design the munications used and the volume sent dictate the program, the project team must study current in amount of buffer memory required. bound processing procedures and decide how they should be done in an upgraded yard. The project 5.2.2.2 Yard Status and Car Records. The team must consider: wbeth'er car lists in a spe project team must determine whether transmission cific order are required for inbound inspections; 69 ROUTING SPEED CONTRe ! UPDATED ADVANCE I CAR CONSIST iLOCATION (Electronic Commun'ication) CRT TERMINAL UPDATED CAR LOCATION OUTBOUND CAR RECORDS ADVANCE CONSIST (Electronic Communication I FIGURE 5-14. SAMPLE DATA FLOW DIAGRAM OF FUTURE OPERATIONS FROM CASE STUDY YARD how the completed inspection results are depends on the present and expected operating reported; whether the results are to be entered procedures. The project team must decide whether onto terminals placed in the field; and how soon data entry terminals will also be required in all inbound processing must be completed so as the departure yard and identify when the outbound not to delay switch,list generation for humping. processing becomes critical (e.g. ,when slow pro The longer car records remain as part of advance cessing might delay a departing train). consist or inbound records before becoming inven tory records, the larger the file needed. 5.2.2.3 Inventory. The size and structure of the inventory files depends largely on the size If waybills are kept as computer records, the of the yard and the size and number of inventory project team must determine how they are entered; reports and inquiries required. (The relation whether they arrive as part of the advance con ship of reports and inquiries to file structure sist, and whether a repetitive waybilling program was discussed in Chapter 3.) The size of the is needed; if so, the team must assess whether inventory, is determined by the maximum expected waybills will add a load to the printing required number of cars that might ever be in the yard. or will require special higher quality printing. The size of the record for each car also influences the file size. A record containing Outbound processing removes departing cars from only ca~ IDs will create a much smaller file inventory and builds the departure and advance than will car records containing destination, consist reports. Whether the program also load, and status codes. The actual record size prints inspection lists, monitors departure is determined by the report requirements and how preparation, and estimates engine requirements frequently the reports are needed. The number 70 EXHIBIT 5-3 FUNCTIONAL HIERARCHY Note: C denotes centralized, and D denotes decentralized. SYSTEMWIDE MIS Inventory by yard, detailed car Interyard communications (C) inf orma tion Paperless record ~xchange for Detailed waybill information/ waybills and interchanges (C) routing Advance consists (C) Demurrage/interchange ,records ,Agency system ' Empty car disposition Motor power unit disposition Accounting YARD MIS SYSTEM Detailed car information, track Determine humping sequence of t~ains number, consist information, Expected cars by block to be humped and history, by car ID Expected train departure Inventory of industrial tracks Interyard communications (D) Yard history by train arrival/ Paperless record exchange for way departure bills and interchanges (D) Clerical handling of waybills Advance consist to/from other Routing by waybill (local cars) yards (D) Routing by waybill ,(D) Accouridng (D) MIS reporting ,Resource scheduling Advance consist to/from sys'tem-, Dynamic track assignment wide MIS (C) YARD INVENTORY SUBSYSTEM (Part of either yard MIS or PC system) Inventory by car position in Inventory reports/inquiry track; track car movement Outbound car list lii'"Yard Switch list generation Classification table Swing tracks by block PROCESS CONTROL SYSTEM Physical control of cars Speed control Reports, Distance to couple--track Alarms--height, cornering, catch occupancy up, lockouts, hot-box detection Automatic routing and switch Hump engine speed control control Manual control override Return updated switch list Trim-end switches of tracks must be known, as well as the length time, memory space to hold the classification of each track and the maximum trac~ occupancy. table, and a communications medium to transmit The project team must decide whether, car move the results to the PC computer. To design the ments' and inventory corrections will be id'enti switch generation function, the number of trains fied by car ID or just by the track position; and cars humped each ,day and their block distri whether the inventory will include all receiving, bution must be known. The complexity of the departure, classification, and shop tracks; and classification is determined ,by the number of whether yard engines will be included in the in cars humped, the number of blocks and tracks, ventory. The information required for cars in and the car distribution. This will also indi shop tracks is determined by the reports cate the memory required for the classification required. table. 5.2.2.4 Switch List Generation. Switch lists The project team must also determine whether are created by matching the block or destination permanent or temporary changes will occur often. of each car with an assigned track in the classi If so, a program must be designed to accommodate fication yard. This function requires processing 71 change of the classification table when neces department or will be a computer-to-computer or sary. If the PC computer is to update inventory man-to-machine (computer) interface. Data flow as each car clears, communications will be more diagrams depicting required functions can be frequent than if an updated switch list is re used to guide the design of alternative hardware turned after each group is humped or if the configurations. The relationship between two exceptions to the original switch list are different functions can be analyzed by noting returned. the volume, type, and frequency of information transferred, files that are shared, input and If a number of rehumpings occur each day, they output devices that are required, and people must be manually entered or if all the rehumped required for each function. Dependent functions cars are pulled from one track, the track inven are more likely to be grouped within a subsystem tory can be used for the switch list generation. or software module. Figure 5-15 is an example The operation of the hump determines the criti of a data flow diagram showing such groupings. cality of the switch list generation and the required availability and allowable downtime of Computer functions are distributed among computer the MIS computer. systems: systemwide MIS, yard MIS, and PC com puter systems (see Exhibit 5-3). The distri 5.2.2.5 Reports ·and Inquiry. The type of report bution of functions between the railroad cent.ral determines the size and type of file management and the yard is often determined by present EDP system required, and the frequency of issuance resources and data processing management philo of these reports and inquiries also influences sophy. Once the location of functions is deter the processing requirement. The reports and mined, functions must be allocated among units inquiries also determine the nUmber, size, and of hardware. Determining factors include cost, locations of printers and inquiry terminals. functional specifications, and redundancy Reports and inquiries might be limited to speci requirements. Functional distribution can be fic terminals or individuals. The frequency of structured along a number of dimensions in issuing a report will be less if the report is cluding: location in the yard, common processing only produced on an exception basis--printed functions (communication, I/O, data entry, file only when the information is out of the ordinary. manipulation), application (real time control, Any report that need not be processed immediately car inventory), and location within the yard is queued to be printed later. In this manner, organization (e.g., clerical, engineering, the computer can process it during a slack signals) • period. The systemwide MIS computer is located at systems 5.2.2.6 Other. The project team must also con central. Among the possible applications are:. sider the number and location of terminals and systemwide inventory; processing of interyard printers. 'For long distances (greater than 2,000 and interrailway consists, waybills, and finan feet), terminals require boosters to receive cial information interchanges; central traffic signals from the computer. If access to the control; and planning and simulation. Union computer or specific programs and information is Pacific's Complete Operating Information (COIN) restricted, the project team must document these system, which tracks car and train movements, details. If the yard computer is to be used for s'ervices inquiries and produces records on move additional functions, such as engine and crew ment history, current movement, and the yard monitoring, management decision aids, and location of cars. Other examples are Southern accounting, the project team must also design Pacific's Total Operations Processing System those functions to estimate their effect on the (TOPS), Missouri Pacific's (MOPAC's) MIS functions. Transportation Control System (TCS), and Canadian National Railway's TRACS. 5.2.3 Develop Functional Configurations Systemwide MIS computers usually do not provide The goal of systems design is to determine the a track-standing inventory within specific yards. best configuration for the functions defined in This function is provided by the yard MIS com the logical model. Many functions in the logical puter. A yard MIS computer usually: is located model of the yard will require automation. The at the yard, provides processing only for that automated functions may be part of one large yard, and. is separate from but in communication computer or they may be divided among a number with the PC computer. MOPAC's Yards and Terminal of smaller systems. System (YATS) is an example. YATS uses a compu ter 'system in the yard to maintain a computerized Step 4 (Figure 5-4) is to designate which func car inventory, support local management informa tional processes will be automated and which tion requirements, generate car classification will remain clerical/manual tasks. Alternative work orders, permit data entry via CRT terminals, hardware configurations can be developed in a and provide a real-time, on-line data base for systematic manner by exploring the distribution local operations analysis (Digital Equipment of functions among independent units of hardware. Corp., 1975). In addition, each YATS site can Elements that constitute the functional design be used to access the TCS, a centrally located of the proposed system can be used as building systemwide MIS computer. blocks within the configuration of hardware and software components. For each alternative, each Another example of a yard MIS system is Union functional interface in the logical flow diagram Pacific's Terminal Information Systems (TIS). A will be internal to a computer or a person/ TIS computer communicates with a yard PC computer 72 ADVANCE CONSIST EMPTY CAR INQUIRY AND REPLY COMMUNICATIONS PROCESSOR ,/ I "I • I \ " /. - - --- ,...... VALIDATED " \ RECORD \ I VIDEOTAPE OF ARRIVAL / \ \ / \ / / CLASSIFICATION ...... TABLE I - MAIN MIS \ COMPUTER - CLERK WITH - INTELLIGENT TERMINAL FIGURE 5-15. EXAMPLE OF DIVISION OF FUNCTIONS TO DEVELOP A CONFIGURATION to transmit switch lists and receive reports of inventory movement. TIS differs from YATS in that it has the capability to act as the yard MIS computer in a number of yards. TISs are to be located in major yards and can be expanded to RAILROAD handle additional smaller or satellite yards, CENTRAL with each yard having a separate data base and OFFICE the same local data entry/inquiry capabilities. RAILROAD YARDS 5.2.3.1. Geographic Distribution of MIS Hardware. MIS hardware configurations may be centralized, decentralized, or regionalized. In a centralized configuration, the yard MIS com FJGURE 5-16. CONFIGURATION OF A CENTRALIZED YARD puter is located at systems central with the COMPUTER SYSTEM systemwide MIS computer. Individual yards do not have on-site computers but communicate with central computers via communications lines and I/O terminals. Figure 5-16 presents a typical MOPAC's Yard Support System is another example centralized system. Yard I/O terminals are of a centralized system. MOPAC has independent typically CRT terminals and teletypes, as in yard computers in its largest yards but uses Southern Pacific's West Colton Yard. At West programmable communications terminals in its Colton, the yard (TCC) and systemwide (TOPS) MIS smaller yards (Lynch, 1977). These terminals computers are located in San Francisco. Micro store and process a small inventory but are wave communication links connect to CRT termi primarily data entry devices for the systemwide nals, teletypes, and printers in the yard. TCS. 73 Centralized control need not be limited to hard information to on-line terminals located in ware configurations. Standardized hardware and classification yards (Lay, 1980). This con software packages and operating procedures in figuration concentrates "the flow of data input yards indicate centralized control. The major and transmission to the central headquarters' factors that suggest a centralized system is computer complex. The geographic coverage of preferred are the rail network characteristics regional centers is determined by operating (a linear rather than grid system), a homogeneity ,territories' and traffic volume. of applications, the low cost of communication lines, and the labor union rules governing Union Pacific is pianning to i~stall computers staffing in local yards. for its TIS system in 13 major yards. These will be independent yard computers linked to the Under a decentralized approach such as the one central systemwide COIN system in a decentral depicted in Figure 5-17, the yard MIS computer ized configuration. When expanded, these com is installed at the individual yard and is under puters will act as regional centers handling the the control of local management. Examples of processing and communications of smaller systems where independent yard computers are satellite yards. 'remotely located are MOPAC's TCS/YATS and' TCS/lncoterm systems and Family Lines Rice and Management philosophy and the structure of Strawberry yards. existing computer resources are the greatest determinants of MIS network architecture. (This CONRAIL is decentralized with some modification. is discussed in more detail in Section 5.2.5.) One inventory is kept at each decentralized In the installation of a new system or modifi local yard, and a separate inventory is kept for cation of an existing system, the most difficult each yard at a central location. The yard design problem is the distribution of functions resident inventory file structure is optimized among the hardware at each site. to produce a track list, while the centrally located yard inventory is designed to optimize 5.2.3.2 Functional Distribution of Yard the search for individual cars. Hardware. Yard MIS and PC functions may be allocated to local hardware using a variety of Although the computers are physically indepen approaches. For example: dent, links to a central system require the existence of some central control in hardware • MIS and PC functions are performed by" and software. Usually, data input and report the same computer. writing software are customized for individual yard needs. • The MIS computer and PC computer are separate and are linked through off-line The regional approach may be viewed as a compro data communication only. mise between the centralized and decentralized approaches. Under this system, yards are grouped • The MIS computer and PC computer are into regions, with each region having its own parallel linked with a larger cent~al MIS computer. The regional yard computer may computer performing railroad system MIS reside at the system central or at a large functions. An on-line linkage also classification yard. Most yards have'only I/O exists between the two at the local 'terminals connected on-line to the re~ional level. computer. Figure 5-18 presents a tYPlcal regionalized system configuration. • 'MIS functions are divided between an MIS or communications computer and the PC Grand Trunk Western Railroad uses regional com computer. The yard inventory is kept by puters to collect data from and send processed the PC computer. CENTRAL COMPUTER SYSTEM RAILROAD CENTRAL OFFICE ,RAILROAD YARDS YARD YARD COMPUTER 110 110 110 110 110 FIGURE 5-17. CONFIGURATION OF A DECENTRALIZED YARD COMPUTER SYSTEM 74 has a distrubted system with five minicomputers in the yard: • MIS - One' inventory control mlnlcomputer - One backup minicomputer (hot standby) • • ' PC system - One minicomputer for retarding and hump engine control. - One minicomputer for automatic route switching. - One backup minicomputer (hot standby). FIGURE 5-18. CONFIGURATION OF A REGIONALIZED YARD These are supported by a central computer 235 COMPUTER SYSTEM miles away in Atlanta. When a train arrives in Sheffield, the central computer transmits car and • The PC computer is s ubord i na te to the train data and a classification code for each MIS computer. car to the MIS minicomputer. The MIS transmits various information, including a classification • The MIS computer· is subordinate to the track assignment for each car and a switch list PC computer. to the PC system (Martin & Durand, 1974). An other example is CONRAIL's Elkhart Yard, where In addition, an MIS, PC, or combination MIS/PC five separate processors are used for automatic computer may actually consist of a number of switching, automatic retarder control, PC backup, smaller computers. An additional computer may MIS applications, and MIS backup. act as a backup to the primary computer. With distributed processing, functions are distributed One variation of distributed process control is equally among multiple computers that link to a partially automatic system in which mini- or each other to share the processing burden. micro-computers or microprocessors perform very specialized tasks in the yard without communica Santa Fe's Argentine Yard is an example of a PC ting.with each other. Another variation is where computer with backup. MIS and PC functions are PC functions are distributed among several data separated, with a computer in the terminal office linked but not control-linked computer systems. building handling MIS functions and two computers For example, the use of a microcomputer at the in the hump yardmaster's office in charge of pro pullout or trim end and a larger PC computer at cess control. One of these PC computers directs the hump end. PC operations and the other is a backup. 5.2.3.3 Case Study Example. A simple example Two yards that have one computer performing both comes from the Potomac Yard case study. Figure PC and MIS functions are Canadian Pacific's 5-11 depicts the major subsyste~s involved and Alyth Yard and Southern Pacific's Eugene Yard. interfaces between them, and Figure 5-19 shows At Alyth, two computers--one primary and one the three configurations that can be developed backup--provide automatic retarding, routing, from the major subsystems. The current Potomac and hump engine control and produce operational Yard configuration is such that all MIS func reports and car inventory. Eugene Yard has one tions are in one processing system. One computer for PC and MIS f 75 MANAGEMENT INFORMATION SYSTEMS PROCESS CONTROL COMPUTER COMPUTER COMMUNICA nONS INVENTORY PROCESS CONTROL SUBSYSTEM SUBSYSTEM SYSTEM CONFIGURATION I COMMUNicATIONS INVENTORY AND PROCESS CONTROL COMPUTER COMPUTER COMMUNICATIONS INVENTORY PROCESS CONTROL SUBSYSTEM SUBSYSTEM SYSTEM CONFIGURATION II MANAGEMENT INFORMATION AND PROCESS CONTROL COMPUTER COMMUNICATIONS INVENTORY PROCESS CONTROL SUBSYSTEM SUBSYSTEM SYSTEM CONFIGURATION III FIGURE 5-19. FUNCTIONAL ALLOCATIONS OF EACH ALTERNATIVE CONFIGURATION FOR CASE STUDY YARD the microcomputer, the internal. logic of which is necessary for a comprehensive evaluation of would control humping to provide smooth the feasibility of the proposed project. deceleration. A number of alternatives will have been devel Another example is the use of a smaller front oped, and a cost/benefit study is one method to end processor to provide communications control quantify each alternative. Important cost fac and queuing for the MIS computer. In the design tors are how long yard services will be disrupted of a distributed system, independent functions during the project and the delay until benefits must be found that require few communications are returned from the investment. back to the main cpu. This allows the detached processors to work independently to minimize A gross estimate of hardware requirements for interruptions that hinder system efficiency. each alternative is necessary to estimate costs. For a PC sys tem, many rail roads have a vendor 5.2.4 Measure Costs and Benefits develop the hardware and software or install a predeveloped package. Informal costs estimates The fifth step of the analysis phase is to may be obtainable from vendors.. For a· more measure the costs and benefits for each option. detailed analysis, the hardware study should be These data become one basis for selecting the begun (see Section 5.4). best system design. Although only relative costs and benefits are required for the comparison of 5.2.4.1 Cost Analysis Methods. The purpose of alternatives, a complete cost/benefit analysis the cost/benefit analysis is to estimate all 76 costs and bene fits over the life of the computer different life cycles, a standard length of time system. Life cycle costing is then used to find for the study must be set. equivalent monetary values with which to compare different alternatives that have varying equip 5.2.4.2 Benefit Analysis. Benefits are much ment and manpower costs incurred at different more difficult to identify than costs -and very times. Future costs can be discounted to an difficult to quantify accurately. Because a equivalent present value, annual cost, or monetary comparison is being made, a monetary benefit. value of benefits must be attached when possible. 'Some benefits are easily identified and quanti The present-value method assumes that each year .fied. For example, if any equipment or personnel of expenditure delay has a positive value equal would be eliminated if a particular alternative to the interest that could be earned. Because were selected, this saving can be considered a of the positive value of delay, any future costs benefit. (future value, FV) may be discounted by that interest to find the present value (PV). The The following possible benefits can be formula for converting future value to present identified with the installation of computer value is: assistance: PV = FV/(l + i) for a single year • Lower clerical costs PV FV/(l + i)n for n year~. Reduction in per-unit processing cost - Space saving To determine the total cost for any alternative, - Reductions of redundant operations costs for each year must be estimated. For - Elimination of tedious, routine jobs. recurring costs over a number of years, the following formula is used: • Improved accuracy of data, ~Elimination of clerical steps PV - Built-in data error checks. 1(1 + 1)n • Better recordkeeping where - Automatic data collection PV = present value at beginning of - Reduction in duplicate files. series A uniform annual cost • Faster reaction time i = discount (interest) rate n = number of years. - Information is more up to date - Easy access to timely information For example, this formula can be used to compute - Faster response to problems. the present value of yearly maintenance for hardware. • Improved information The total present value equivalent for an - More detailed information available alternative is found by totaling the present for management decisions. value of each year's expenditures. The total is - Problems can be detected and corrected therefore: early. - Less important information can be n filtered out. PV = ~ FV(j) j j=O (1 + 1) Tables 5-1 and 5-2 identify some specific benefits derived from the use of MIS and PC computers. Although quantifiable benefits are where gained from improved clerical operations, of FV(j) the cost incurred in year j greater importance is the improvement in yard i = discount rate operations and service. The difficulty is to n = years of the life cycle estimate the amount saved as a result of better PV= present value. decisions and operational imprQvements. To quantify these benefits, actual performance For each alternative, cost estimates must be made improvements in yard operations must be esti for equipment, installation, software develop mated' and the monetary benefits estimated from ment, and annual operating costs. Exhibit 5-4 that. This is a difficult, inaccurate task. is a sample work sheet for estimating capital Some examples of monetary benefits are as and recurring costs. The cost, the -year the follows: cost is incurred, the life expectancy, and the salvage value are required for each capital • Meeting schedules accurately--Cars are expense item. For recurring costs, the annual better utilized; increased business may cost and number of years incurred are required. result from improved customer service. When comparing different alternatives of 77 EXHIBIT 5-4 SAMPLE COST/BENEFIT WORK SHEET fear Coat Life Salvage One-Time Costs Cost Incurred Expectancy Value Feasibility study, system design Hardware purchased Field equipment Communications equipment Cost to rework yard yard layout Site conversion/modification Power supply Air conditioning Training Implementation and installation Disruption of current operations Recurring Costs Cost Period Maintenance/replacement Energy Space rental Communications Supplies Hardware lease payments Additional personnel System operator Maintenance/repair Programmers/analysts Management • Humping speed--Greater blocking capacity • Proper coupling--Fewer uncoupled cars may lessen the need for additional hump mean that tracks need not be shoved as yards in the future. Increased yard often. Fewer overs peed impacts lower throughput means each car spends less costs of damage to lading and cars. time in the yard and is better utilized. 5.2.5 Select Option • Hump and crew utilization--Savings in personnel and energy may be realized. The. project team next compares options to decide on a particular one. A number of nonquantifi • Track occupancy--Track utilization able factors such as management structure, data decreases the need for additional yards processing centralization, hardware compati in the future and provides a better bility, and union agreements usually become return on the investment in the current ·important. Once art option has been selected, yard. the project team can provide management with a budget and schedule; and because the physical • Switching reliability--More time is requirements have been defined; the team can available for humping when the humps begin the hardware study. need not be closed for removal of misswitched cars. Corporate policy affects the relative weight given to hardware costs, crew ~fficiency, information access and service to shippers, 78 Table 5-1 JUSTIFICATION FOR PROCESS CONTROL COMPUTER USE Improvements Over How this . Effective Overall Conventional PC Ie Done by PC System PerformaRce Few misclassifications Car identification and switching Less time lost logic are more efficiently done Increased throughput with computerized PC Reduced engine time Automatic generation The PC computer keeps track Eliminates time ordinarily required of misroute report of misroutings. for searching for lost cars Therefore, it can produce a Labor savings report on request. Higher humping rate This is achieved through better Increased throughput of the hump engine speed control. yard Better track utilization The PC computer maintains track Increased storage capacity of the occupancy and inventory infor , yard mation on a real-time basis, Increased throughput which provides a more dynamic A more sophisticated sorting and track assignment scheme. blocking scheme may save time for the downs team yards More timely car location The PC computer maintains track Quicker response to customer information occupancy and car inventory in inquiry formation on a real-time basis, Reduced search time in which provides a more dynamic locating cars track assigmnent scheme. More optimal retarder Automatic retarder control can The reduction of underspeed (im control provide a higher level of ac proper spacing) can reduce crew curacy (+ 1/4 mph) and consis and engine use. tency in-the speed at which a car Both improvements mean the saving leaves a retarder than csn human of lost time due to corrective retarder operators. In manual actions, which amounts to in operations, improper switch list creased yard throughput. information may cause cara to be retarded inadequately or exces sively. This resul~s in car spac- ing problems and overspeed im- pacts. In manual operations, there may be higher average coup- ling speeds because of a tendency for operators to release nonfragile lading at higher speeds than fragile lading. Overspeed impacts weaken couplers and yokes; computerized con trol reduces these occurrences, there by reducing the number of damage claims and car repairs. Car spacing problems are to a great extent alle viated by more accurate retardation, resulting in fewer stalled cars. Early detection of bad Automatic detection of bad axles Saves time in "digging" the bad order cars by wheel detectors will cause order cars out from the classi automatic detour of the bad-order fication tracks later cars to the maintenance area be Saves crew and engine times fore classification. Reduces damages later if the bad-order cars are not left undetected Automatic integration The PC computer can sense and Increased throughput of speed control utilize speed control data from Saves crew time snd engine time the bowl area .to adjust speed and energy control parameters at the crest area or vice verBS. Quicker and more positive The automatic processing of in Reduction of misc1assifications, identification of inbound bound train consists and display which means better throughput cars of switch Ust's dynamically as and fewer crew and engine the train is being humped, plus requirements the verification of individual Less error in car inventory and car identifications by comparing car location data results in wheel detector input with better management and customer computer-stored records, give relations. quick and accurate identifica tion of cars. More automatic area The automatic setting .of switches Saves manual switching time train protection and to lock an area in order and turn Reduces routing conflicts, thereby release it over to local control and the reducing crew and engine time, release of such control are done and increasing throughput by the PC computer via CRT ter Reduces car damages minal interaction. 79 Table 5-2 JUSTIFICATION FOR MANAGEMENT INFORMATION COMPUTER USE Improvement Over How this Is Done Effective" Overall Conventional Methods by MIS compu ter System Performance Up-to-the-minute Disk-based PICL maintains track Quicker response to customer detailed inventory occupancy/order and car inventory inquiry information. Reduced car search time More accurate train makeup infor mation, decreasing errors and reswitching Provides information for more accurate demurrage accounting Improved data entry Data entry/retrieval using More accurate data entry retrieval formatted CRT screens. Easy, fast retrieval of information used in decision making" Reduction/elimination of the ex pense of some preprinted forms Improved data access Low-cost CRT terminals located Better inventory control when and communications throughout the yard. responsibility is given to respective department More accurate input as data source enters information Personnel time savings because of easily accessible data Better recordkeeping Disk-based data storage with Reduced expense of preprinted forms automatic recordkeeping from Less voluminous record storage event transactions. Tape backup Increased data accuracy and acces- for permanent record storage and sibility automatic audit trail generation. Fewer clerical personnel Better reporting Computer processing power can More accurate and comprehensive produce reports that are unob reports tainable by manual methods. In Reduced manpower for report formation can be presented via production CRT displays or as hard copy at Reports a~e seen earlier by multiple locations. A well . decision makers defined data structure can be easily manipulated for new re port production. Automatic data transfer Computer-to-computer communica Reduced manpower needs to systemwide centralized tion automatically transmits More accurate data transfer computer inventory and other information. Computer-assisted waybill Computer-generated waybill format Fewer waybill errors generation on CRT automatically enters repe Reduction in clerical effort titive information. There is Faster processing speeds for on-line rate calculation by the revenue collection computer and the completed bill is automatically printed. Automatic information Waybill, consist, and interchange More accurate information in te rchange reports and information can be Reduction in clerical effort transmitted to another line's Faster processing speeds for computer automatically. revenue collection " Automatic switch list Automatic switch list generation Reduced personnel effort generation and dynamic from inventory records of car Quick transfer of information to track assignment destination and track/block" locations in the yard. assignment. On-line computer More accurate switch lists to re assistance for track assignment. duce car-handling errors Increased throughput " A more sophisticated sorting and blocking scheme may save time for downstream yards Fewer throat conflicts, better trim engine and crew usage Crew assignment and Work requirements and predictions Efficient work force utilization tracking are used to assign work tasks to Less overtime pay the proper employees and crews. Reduction in penalty pay costs Accurate records are kept and Accurate and detailed worker the computer monitors work rule productivity reports violations. Automatic transfer of work records to payroll at the central computer Outbound train makeup Current and predicted inventory Optimal trim engine and crew usage information is used to determine Decreased congesti"on in yard optimal train makeup, engine use, throat area and trim operations. Efficient use of line haul engine. and crews 80 service for other railroads, information timeli field OP personnel are located. at yards or ness, and the different methods used to measure centrally. the operational efficiency of a yard. The centralization or decentralization of management Currently, the management philosophy of most usually parallels the struct~re of the authority railroads tends to be "risk adverse.". The over and location of computer resources. railroads tend to choose computer hardware with Railroads that tend to have a high level of less capability but for which a vendor can local control usually offer easier information guarantee computer support and maintenance. access, have software autonomy, and place a However, if the computer skills and technical greater emphasis on automatic yard decision aids. know-how are available within the railroad, management can adopt more innovative hardware Management within the yard and the autonomy of and applications. individuals and departments influence the access to computer resources at the local level. With Management's perception and understanding of the in a yard, the flow of information can be cen future technological trends and cost-performance tralized through an EOP department and computer trade-offs in computing capability, computer room, restricted to "privileged" users by re memory, telecommunications, and software greatly quiring security and an access code to CRT influence the system architecture. Those mana terminals and files, or it can be decentralized gers who believe the principal cost will be in by allowing individuals to enter information to software arrive at decisions differently from add to or change the data base directly via CRT those who believe the greatest costs will be in terminals located throughout the yard. telecommunications or in computing capability. For example, a railroad may choose centraliza Union agreements at different railroads and yards tion of computer operations because of excess may also influence system design. Computer capacity in common carrier communications lines operators, required for a large centralized along its right-of-way. system, may be classified as clerks. If a de centralized replacement is suggested, in one 5.2.6 Functional Specifications interpretation clerks may be required to enter or change data from any CRT terminal in the As part of system design, the project team yard. For example, car control actions made by develops in the analysis phase a set of func operations personnel on a PC computer may also tional specifications. In addition to the use change inventory records on the MIS computer. in systems design, specifications advise the In some railroads, OP personnel must be classi users how the new system will affect them. fied as management personnel. Therefore, the Functional specifications include: . installation of a new or larger computer system may require more "managers" to work in a yard (1) A statement of preliminary equipment than are allowed by labor agreements. A restric requirements. tion on crew size may remove any labor savings attainable from the installation of a PC system. (2) A list, as well as samples, of all reports and other output from the One of the main institutional considerations in system, documentation of the flow of yard computer applications is the attitude to paperwork, frequency of reports, ward computer failure and downtime. In certain number of copies required, distribu railroads, the management philosophy is that a tion of these copies, and any special yard must operate at maxUnum capacity all the requirements. time, so the railroad is willing to pay for a highly redundant system that guarantees no loss (3) Performance requirements, which serve of computer capability. Other railroads could as source material for subsequent test tolerate a degraded mode of operation for a short specifications and acceptance tests. time, thus requiring a less costly backup com puter system capability. Attitudes toward down (4) Information on each file or data base tUne lead to important considerations of product and its probable contents. support and maintenance. Vendors with more extensive support services covering a large (5) Processing requirements that discuss geographic area may have a distinct marketing topics or functions to be performed by advantage. Thus, management's perceptions of the users and the computer. the relative importance of individual yard func tions are important in the analysis of trade-offs (6) Proposed organizational changes and between complete and partial redundancy of the changes in clerical procedures. hardware that automates these functions. (Staff requirements for the next few years may be projected at this time.) Another institutional consideration is whether If interactive systems are to be used, the field OP service personnel are to be located scripts are developed to specify at headquarters, in regional facilities, or at procedures for terminal users. the yard. Having field OP personnel at the yard facilitates a decentralized system architecture; Functional specifications are revised until the having them at headquarters facilitates a more project team and user representatives agree. centralized system architecture. Labor agree This level of detail is sufficient for the ments concerning yard personnel influence whether 81 procurement of stand-alone PC systems from a processing response. Low~priority batch jobs turnkey vendor. can be processed in the "background": Because output is not needed immediately or inter The specification will be assembled from docu- actively, the percentage of CPU allocated to 'ments and exhibits compiled from each step of background jobs depends on the needs of the the analysis, data dictionaries containing foreground jobs. definitions of system interfaces and files, and a complete description of the internal logic of To provide the equivalent ,of a larger main memory each process of the logical flow. The specifica to permit running larger programs on a smaller tion will also document the partitioning of computer, virtual memory ~r program o'verlay tech functions among computer systems and subsystems niques may be used. Overlays allow use of the and individuals and departments. The specifi same memory location for different programs, and cation will also include performance targets for the virtual memory system uses disk memory as an systems installation and acceptance. extension of the main memory. ' 5.3 SOFTWARE DESIGN PHASE If the computer configuration provides re dundancy in case of failure, the operating In the software design phase, functional specifi system must be designed to detect the error, cations are expanded into a:system specification switch hardware, and restart applications. to provide more details on man-machine inter Failure recovery may be designed to be com faces, user procedures, performance requirements, pletely automatic or may ,require various degrees the structure of software partitioning and of manual intervention. modules,' and more detailed design of data files. Hardware requirements are important inputs from 5.3.1.2 Information Storage and Access. Yard the hardware study. If a PC system is to be pur MIS applications require large amounts of data chased, the software design phase may not be to be stored. An inventory program relies almost required before the procurement process begins. exclusively on file access and manipUlation In some cases, the software design phase is routines. Files must be designed to use space completed by the vendor. efficiently while remaining easily accessible for frequent inquiries and changes (also see 5.3.1 ,MIS Software Characteristics Section 3.2.2). An'efficient inventory file structure should: 5.3.1.1 Operating Systems. Many of the advances in and distinctions between yard management com • Minimize st~rage needs. "puter systems have been in the development of operating systems. Older ,computers use a serial • Minimize the search for storage 'batch operating system limited to execution of a locations when adding records. single job. This is adequate for simpler appli- cations, such as the card'-PICL system. • Easily monitor car locations. Newer yard computers must concurrently perform • Easily provide car information by multiple processing tasks, provide on-line data track-standing 'order. input and retrieval', and service multiple com munications lines. A multiprogramming or time • Minimize the search effort to locate a sharing operating system can provide, these particular car. services (Section 2.4.1.3). A yard management computer may operate by following a predeter Missouri Pacific IS YATS 'system uses three dif mined cycle of tasks, or it may operate in ferent files to store,car ID, car records, and response to random interrupts requesting pro car position. The 'car index file (CIF) stores cessing·. If, the inventory program receives car IDs in an easily accessible order. A pointer information directly from the yard PC computer, for each car indicates the location of the car its operating system should be interrupt driven information in the car record file (CRF). A to ensure prompt. servicing of the PC computer, third track inventory file (TIF) stores in which may have limited storage capacity. dividual pointers to the car record file in the standing-track order of the yard. This file When mUltiple programs are run concurrently in structure allows the bulk of the information to the same computer, a priority structure is needed be stored randomly and efficiently in the car to ensure the speedy processing of important or record file while remaining' accessible by ID or time-critical jobs. For example, an on-line location through the CIF and TIF files. application, such as car location inquiry, should take priority over switch list generation, which Union Pacific uses a similar file structure. 'may in turn'· take precedence over production of The difference is that the TIF includes both a periodic management reports. ,pointer and the car ID, so that a car can 'be moved in inventory by specifying the track and Foreground/background processing is one tech car ID as opposed to the "track sequence number." nique for efficiently processing high- and low The software for yard inventory systems is very priority tasks together. High-priority'on-line similar to standard inventory packages. Infor 'jobs are processed in the "foreground"; that is, mation can be stored and large files can be they are serviced interactively and are given a accessed efficiently using data base management high percentage of CPU resources to ensure quick software. 82 Journal files are necessary for an accurate Computer-to-computer communicati·on in classifi record of yard operations. Files can be copied cation yards is required for internal-yard periodically to act as a checkpoint, or a record distributed processing, MIS-to-PC computer of transactions c'an be made to act as an audit linkage, and sending and receiving external trail. messages. Distributed processors must com municate large volumes of' information quickly. 5.3.1.3 Input/Output Terminals. If the project The linkage between machines may be a high-speed team decides to provide easily accessible CRT or communication line, a shared communications bus, teletype terminals throughout a yard, display a direct-memory access channel, or a' shared software must be obtained. Efficient proces memory. sing, good communications, and an interactive mUltiprogramming operating system enable many The PC computer, as a real-time system often users to access a computer simultaneously. Once with little memory capacity, must be able to hardware requirements are met, display software communicate immediately to the MIS system. The and data base accessing procedures must be MIS computer must therefore buffer the stream of designed. Terminal software should: incoming messages from the PC system until they can be processed. ,When the PC and MIS computers • Provide fast data input. are separated by a great distance, messages must also be formatted for transmission. • Promote aC'curate data input. The communication to other yards and to the • Be nonthreatening and easily acceptable railway central computer need not be as time to yard personnel. critical. Messages may be stored and sent periodically as a batch to an outside location. • Present displays in an easily readable If a direct link between railways is not used, form. messages can be routed through a common computer such as the Association of American Railroads The first consideration in the design of user TRAIN II communication network. procedures is the method to use for data input and output. One method is to designate an 5.3.1.5 Software Languages. The software English type of command, such as "Enter car 10." language chosen for use in the yard MIS computer If many commands must be memorized, however, system should be well suited to file accessing, problems may develop. A popular solution has file manipulation, and report and display gener been to ca 11 for a "menu" of commands. The user ation. For management applications, considerable selects a procedure from the menu by specifying scientific processing and mathematical computa a number or symbol. In Southern Pacific's West tion are not required. Colton Yard, the user may ask for a menu or enter the required function symbol directly. In the In general, MIS applications on a large computer selection of some functions, the user receives a fit well with high-level business- and file list of applicable choices. An example is a oriented languages, such as COBOL. Programs request for an inbound train consist. This written in a high-order language are preferred request prompts display of a list of the identi because they are easier to develop and modify. ties of all incoming trains, ,'aod the user is Programs written in a standard machine requested to select a single train by placing an independent language are transferable to other "X" beside the 10 number. machines and can take advantage of software developed on other machines. If a microproces If processing power is sufficient, large, compli sor is used for an application such as communi cated input procedures can be presented on a CRT cations processing, a lower-level language may display by a self-tabulating input form that be preferable. Because of the smaller memory requires the user only to "fill in the blanks." and processing power, microprocessors benefit The user is queried for information, and after from the efficiency of assembly languages. each field is entered the computer can immedi ately check for data entry errors and demand 5.3.2 PC Software Characteristics immediate reentry if an entry is incorrect. PC applications have traditionally been written Report generators are software tools the user in low-level assembly languages. Assembly can use to design data output formats. Report languages have been preferred over higher-level generation programs interactively query the user languages such as FORTRAN because of their faster on data fields, sorting, and presentation. This execution times, compact code, and ease of direct enables the user to quickly design a "one-time" access to I/O data. For a higher level language or permanent management report. to be successfully used, the compiler program must efficiently compile programs into quickly 5.3.1.4 Communications. If the MIS computer executable code and permit detailed manipulations must communicate with another computer, software for concentration and verification of the in may be needed for the interface between the two coming and outgoing field sensor signals. machines. Messages must be reformatted, incoming messages must be decoded, and messages must be Because few PC applications require specially queried to ensure proper timing. designed hardware, general-purpose computers are 83 adequate for railroad yard applications if they After the system narrative has been completed, are equipped with an efficient real-time oper systems analysts write specifications for in ating system. One capability that is valuable dividual programs that state what the programmers for railroad PC applications is priority must accomplish. First, the, functional specifi structured interrupt-driven task scheduling. cations are broken into their component parts so Software development systems usually require a that system modules may be defined. The logical large disk-based operating system. If the soft control and sequences to execute each function ware is developed on another system, _a smaller, 'are then identified. Detailed design should simpler memory-based real-time operating system specify data names, formulas or specific logic, is usually sufficient. If a high-order language for complex routines, and'record layouts. All is used for programadng, a valuable feature is conditions should be covered, so flowcharts, data to allow lower level system and I/O commands to flow diagrams, and/or decision tables may be be called from within application programs. helpful at this point. System specifications should be finalized and approved before program 5.3.3 Software and File Redundancy ming begins. Often a committee of people from different depar~ents and yards that have a When MIS and PC functions are divided between stake in the system is formed to review the two computers, the PC system relies on a number design. of MIS functions. In normal operation, the MIS is expected to periodically provide new switch The project team should prepare a procedure for' lists assembled from the receiving yard inventory modifying the final specifications; this proce and classification table. Continuous humping dure should include reviews by the affected users therefore depends on the MIS computer's timely as well as management. The procedure can be completion of this function. This dependence J formalized through request-for-change forms that can be avoided by having redundant functions and document the requested change, the person and files in the PC computer. department requesting the change, the associated benefits and costs, and whether the change should Two schemes may be used to provide this redun be effected immediately or can be postponed. A dancy. The first is to store a number of up formal review and modification request procedure coming switch lists in the PC computer, and the is required for software developed by a vendor second is to store the receiving yard inventory but should be completed by an agreed-upon stage and the classification table in the PC computer. of development. The choice depends on the expected repair time for MIS computer failures and available storage 5.4 HARDWARE STUDY in the PC computer. If the repair time (MTTR) is short or the MIS can_be quickly reconfigured The goal of the hardware study is to design and to a downgraded single computer with switch list specify computer hardware and other equipment. generation, then only a small number of switch An MIS hardware study covers new hardware selec lists need be kept to ensure continuous humping. tion, design of additions and upgrades to the If longer or complete failures of the MIS cam present system, and an evaluation of the effect puters can be expected, more software redundancy on and interface with the existing system. The is required. In this case, the receiving yard hardware study for the PC system is not likely inventory and a classification table are stored to be as comprehensive because in most cases PC in the PC computer and are used by redundant computer hardware is part of a complete turnkey software to generate switch lists when required. package. In the analysis phase, the project In both cases, the final inventory location of team may have already identified the' design, humped cars must be stored on disk or as punched constraints, interface, reliability,' and perfor cards until the yard inventory can be updated on mance informati'on required. A PC hardware study the MIS computer. is likely to concentrate on interfaces with the existing or projected MIS system, reliability 5.3.4 Software Specifications requirements, and redundancy solutions to be implemented by the selected vendor. System specifications for software include the basic design for the programming system and The hardware study is begun during the analysis subsystems. Before programmers begin working, phase to provide general hardware trade-offs and they must understand the system objectives and costs for use in comparing alternatives (Step 6, specific responsibilities that they will have in Figure 5-4). Hardware specifications are ' developing the software. To provide, this infor completed in detail after the analysis phase. mation, the project team should prepare a written narrative that describes the new system. This To begin the hardware study, the analyst reviews narrative should ideally contain a description the data on the current volume of classification of the type and extent of the system, the general operations and information processing that were design concept, and a brief statement of the pur gathered during the first step of the analysis pose of each program. This narrative is used for phase, description of current operations. By actual program development when software is comparing the functional diagrams of the current completed in-house. If software is to be sup system and the selected alternatives, the analyst plied by an outside vendor, the vendor may identifies the changes between systems, added complete the narrative. It then can be used to functions, and newly computerized functions. Any agaLn confirm user acceptance and understanding expected Lncreases or decreases in the future of the proposed system. volume for any function must also be noted for 84 determining the size of various hardware com The first model constructed is of the complete ponents· and evaluating the need for software. configuration and includes a representation of The hardware and software for any function that the interaction between significant resources; is expected to expand in the future should be Figure 5-21 is an example. Information is sufficient to incorporate the added volume, gathered on device characteristics, the struc unless it is cost-e ffec ti ve to add add i tional ture of expected software, and operating system capacity later. The results of the analysis and CPU scheduling methods. Data are also phase are also used to examine the structure of gathered on the present and expected work loads the software, including file size and structure. including volume of user input and requests, data storage resource requirements, individual The common bottlenecks encountered in designing device utilization, and the required system a computer system are in the processor, in the response time. This information is available cd-iskdr-ives, and in comnunication to the user in from the operational data gathered (Section the yard, other yard computers, and to computers 5.2.1.1). outside the yard, such as a railroad systemwide computer. TERMINALS 5.4.1 Hardware Requirement Analysis To estimate the required size of computer hard ware- for any configuration, mathematical modeling analysis, simulation, or empirLcal formulas can be used. Explaining these methods in detail is beyond the scope of this manual. More detailed explanations and additional references are avail able from the following sources: J. Martin, "Design of .Real-Time Computer Systems" (1967); the articles in Computer (1980) and Computing Surveys (1978); E. Yourdon, Design of On-Line CPU Computer Systems (1972); and HarbDan et al., J Management Information Systems Handbook (1968). CHANNEL [ With mathematical modeling, assumptions are made about the method the operating system will use to sequence and service programs. The simplest DISK DRIVES is to service all programs equally on a first come/first-served basis. Other schemes are to [ sequentially process jobs, process jobs with higher priority first, handle I/O requests first FIGURE 5-21. SAMPLE CONFIGURATION MODEL and use the remaining time for processing, or allot each job a predetermined time forproces sing before switching to another job. For any particular configuration, the following hardware characteristics must be identified: The servicing scheme is represented by a mathe instruction timing, main memory size, main matical model, as is the arrival rate of data memory cycle time, cache size, cache cycle time, and processing requests. Figure 5-20 represents memory access time, number of disk drives, a simple model of processor servicing. A Poisson minimum and average seek time, average rotational distribution is often used to represent a random delay, disk transfer time and volume, priority distribution of input from user terminals. Be servicing for hardware and software requests, cause of the random nature of request arrivals, the number of terminals, and the scheme for queuing theories are used to estimate the waiting terminal and other I/O servicing. The analyst time associated with high system loads. This must also estimate disk accesses and processing will provide an estimate of the percentage of time per transaction. A number of analytical response times that will be at an unacceptable models (BESTll, CADS) are commercially available. level for any given processing capability. In contrast to mathematical models, a simulation model uses a computer to estimate characteris QUEUE SERVER tics of hardware in the expected operating environment. The program uses input and processing characteristics to generate such • statistics as maximum and average queue sizes, distribution of user response times, hardware A-VERAGE·--J utilization, storage requirements for buffers REQUEST ARRIVAL 0 .. and queues, and maximum throughput (Martin, RATE fRequests AVERAGE SERVICE per Second) CAPACITY fRequests 1967) • per Second) Some hardware vendors offer simulation packages FIGURE 5-20. SAMPLE QUEUING MODEL OF PROCESSOR for their specific hardware-for example, SCAPE SERVICING for IBM systems using MVS operating systems 85 (Schiller, 1980) and the IBM VM/370 Predictor inventory movement, yard status reports, on-line (Bard, 1978). Other independent packages are dynamic track assignment, and the like), the available commercially, such as SCERT (Hermann, processing capacity must be great enough to 1967). In addition, a number of simulation provide adequate response ti.mes. In addition, languages are commonly used--SIMSCRIPT, SIMULA, the CPU must be capable of processing a large SIMPAC, and GPSS III. SUnulation models can amount of character and file manipulations for also be written using standard languages such as inventory applications. The CPU must quickly COBOL and FORTRAN. process a large number of file transfers for inventory information transfers between PC and The use of common empirical formulas is a third MIS computers and interyard information trans hardware requirement analysis method. A number fers require. of common factors have been observed with on-line business computer systems, and some may be appli Decision and planning aids require a powerful cable to yard computer systems. For example, the CPU. Scheduling/utilization algorithms, statis average typing rate at a terminal is one or two tical analyses, and yard operation simulations characters per second. It has also been observed may also require considerable CPU power. If that a transaction' is completed every 30 to 60 these functions can be completed off-line during seconds. These numbers, used in conjunction with non-peak hours, total CPU power requirements can the work load estUnate of clerical functions in be reduced. a yard, can roughly indicate character and trans action arrival rates. Word size becomes important when large amounts of data must be transferred quickly and stored Another observed reationship is that a minUnum efficiently. Word size is not as important for of 8 to 10 or an average of 15 to 20 disk arithmetic processing because there are few accesses are.required for processing each trans floating point calculations for inventory, action (Yourdon, 1973). This relationship varies management reports, and interyard information with different programs; some complex reporting applications. programs may require many more disk accesses on the average because of the file access methods, CPU sizes vary with application and yard size. such as indirect addressing used to access Southern Pacific's Terminal Control Computer multiple files. services several yards with real-time inventory, manag~ent reporting, and other functions using Another empirical formula often used is n = T/P large mainframe computers. The Yard and Terminal + I, where T is the arrival rate of transactions, System (YATS) of the Missouri Pacific Railroad P is the average processing tUne, and n is the (MOPAC) was designed for a.yard handling 500 to obtained estimate of the number of active 6,000 cars per day. It supplies a track-standing terminals a system can support (Scherr, 1967). inventory, management information report, task tracking, and an on-line data base for operations 5.4.2 MIS Hardware Characteristics analysis using a 16-bit minicomputer with a main memory of only 80K to 128K woyds (160 to 256 KB). The hardware characteristics of a particular Southern Railway's Terminal Information Proces classification yard MIS are determined by the sing System (TIPS) consists of two 80K mini applications that are to be processed. This computers for inventory and switching control, section discusses how each type of hardware waybill generation, industry inventory, demurrage component is used and how it is affected by each accounting, and work-order tracking and analysis appli cation. (Whii:ehead, 1977). . 5.4.2.1 Central Processing Unit. The CPU must 5.4.2.2 Mass Memory. Mass memory normally con be chosen so that it is capable, within time sists of magnetic disk memories or, in smaller constraints, of fully processing the work load. yards, flexible diskette memories. By far the The PC computer must be capable of operating as greatest use of mass memory in yard MISs is on a real-time system, whereas the MIS computer line inventory files. The size of mass memory need not be tUne critical in all its applica required varies directly with the maximum number tions. All the MIS applications may be completed of cars in the yard inventory, the amount of using a batch operating system as long as no information stored for each car, and the length on-line inquiries must be returned to either a of time the information is on file. Examples of terminal or the PC computer. If the MIS computer disk size requirements are Southern's TIPS, with is a batch system, the CPU need only be capable 40 million bytes (MB), and MOPAC's YATS with 8 MB of processing the average load of a 24-hour to 80 MB for 500 to 6,000 cars and its INCOTERM period. Batch processing is adequate for daily System with a 1 MB diskette for 300 to 500 cars. inventory records and management summaries. Because of lower hardware costs and greater reli ability of the Winchester type (sealed) of disk Real-tUne applications require that peak loads drives, MOPAC has been replacing the diskettes be processed quickly enough to return time with 24 MB drives. valuable information. If the PC computer relies on the MIS computer for such information as Inventory records can also be kept'on cards or switch lists, this information must be returned tape, but this limits the speed of processing promptly or yard throughput will decline. If and memory access. Tapes are used extensively CRT terminals are to be used for on-line inquiry for archival record storage. and data entry (such as inventory inquiries, 86 5.4.2.3 Card and Printer I/O. In the first Terminals may be displays only, or they may in yard computer systems, cards were used almost clude a processor that can relieve the main com exclusively for data input, mass storage, and puterof some functions--data entry fonnatting, data transfer. Printers provided the data out for example. If the terminal also has internal put and a permanent storage medium. An example storage, data can be condensed and stored for is the Pernnan Yard of the New York Central later, more efficient, less costly transmission. System, which was built in 1968 (Karvwatt, 1968). The main computer need only occasionally query This yard was equipped with card readers, card the terminal for data. Intelligent data entry punches, and high-speed printers to enter and terminals are cost-efficient because they save retrieve bulk data from the computer. The high communications costs or off-load tasks to ,primary input were train consist card decks and postpone or reduce an upgrade of the central the primary outputs were switch lists, corrected facility. switch lists ,and track inventory cards. All yards using card-PICL systems rely on card and CRT terminals are used for on-line inventory printer devices. inquiry and management reporting and as on-line decision aids., Special displays can be used for In many recently built yards, data input, mass the graphical representation of yard inventory storage, and data transfer functions have been distribution or a real-time representation of taken over by CRT terminals, disk and tapes, and the humping sequence. data transmission ,carriers. Printers are still the best and fastest method to receive a hard The distribution of CRT terminals differs from copy of information from the computer but CRT yard to yard. Southern's Savannah Yard has keyboards have replaced cards and printers for seven CRT terminals and two printers located in data input and inquiry. In Southern Pacific's the yard and agency office, one CRT terminal West Colton Yard are 32 CRT terminals, compared and one printer in the yardmaster's tower, and with only 11 printers and 9 teletypes. The three printers in the switching area (Whitehead, printers are used for printing large-volume 1977). In Union Pacific's Terminal Information reports, and the teletypes are used for logging System, CRT terminals and printers are distri alarm and maintenance messages. ,A card reader/ buted among the yard office, the yardmaster's punch acts as a backup for the communications office, the mechanical facility, the TOFC ramp, link between the crest control (PC) and terminal and terminal control (Anderson, 1977). control (MIS) computers. In Santa Fe's Barstow Yard, high-speed card punch/processor/printers 5.4.2.5 Long-Distance and High-Volume Data are backups for the yard computer to transmit Links. Data links to remote locations are used data to the hump computer and to Santa Fe's in three situations. The first is where the central computer in Topeka (Progressive yard MIS computer is located in the yard but Railroading, 1976). must communicate with the railroad's central computer. Examples are Santa Fe's Barstow Yard 5.4.2.4 DataLInput and Inquiry Terminals. As microwave link to Topeka, Louisville and computers have become more powerful and operating Nashville's Strawberry Yard data link to 'systems and software have become more sophisti Jacksonville, and Southern's Sheffield Yard cated, price performance has greatly increased. 2,400-bps data link to Atlanta. Thus, classification yards have been able to afford real-time and on-line BIS. With installa Alternatively, the yard management computer tion of on-line systems in newer yards, most itself may be located at a remote central site. card punch equipment has been replaced with CRT Southern Pacific's Terminal Control Computer terminals and other data/inquiry termi"nals. CRT (TCC) is located in San Francisco--more than 400 terminals provide a fast, accurate ,data entry miles from its West Colton Yard. Direct access system that mirrors back input for immediate is provided for the crest control computer and self-checking. Low-cost CRT terminals can be 52 printers and CRT terminals by a direct micro strategically located throughout the yard, wave link. These devices operate 'as if the allowing easy access to speedy data input and computer were located physically in the yard. inquiry. With entry of data into a yard data base, much of the intrayard communication can be The third area of data communications is inter completed using only CRT terminals, saving time yard and interrailroad communications. Rail and eliminating much of the transfer of written lines communicate via direct computer-to-computer data. When needed, smaller terminals can be links, using teletypes or high-speed printers, moved to ,any place where telephone lines give or through an intermediate computer such as the computer access. Association of American Railroads TRAIN II communications network. An example is paperless In card entry systems, a difficult, rigid, interchange reports (Section 3.1.10.2). column~by-column data entry format is required, but data entry via CRT terminals can be formatted The high volume of data on waybills and consists to provide easy man-machine ,communications. Data requires high-volume I/O channels for each com entry programs can query the user to select a puter system. One of the greatest difficulties data entry type from a set menu,and then prompt of high-speed communications is the design of a the user for each specific item of data and then compatible interface between computers. 'Data check the entered data for formatting and logic formats, protocols, and speed must be matched errors. This type of advanced data entry format for direct communications. In most cases, ting reduces errors and training time. standard hardware can be purchased and minor 87 programming changes made to provide a satis functional system specifications and are factory interface. In more complicated situa discussed in Chapter 4 and Section 5.3.2. ions, an intermediate communication processor is used. During the earlier stages of computer develop ment, the PC computers were considered as a 5.4.2.6 Microprocessors. Recent advances in special class and were designed differently than computer technology have provided in smaller general-purpose computers. Examples of these mini- and micro-computers that offer large special-purpose computers are the IBM 1130 and amounts of processing power for relatively the Honeywell 316, 416, and 516. The unique little cost. This less expensive computer power features of these computers are their word size, provides the opportunity to use independent special front-end I/O interfaces, dynamic inter processors to process parts of current appli rupt features, and real-time-oriented computer cations as well as for previously untried instructions. applications. A number of applications now using minicomputers are applicable to micro As computer technology became more sophisticated, processors. the difference between the special-purpose compu ters and the general-purpose computers gradually Microcomputers can be used in two ways. One is narrowed. Today, except for a few applications to group them as dependent processors to share (e.g., space flight, military command-and the equivalent work load of a single MIS com control), the PC computer is basically 'a general puter., ,By distributing the processing among purpose computer, with the addition of certain many computers, the failure of one component has readily available operational features. This a lesser effect on total system operations. In section presents an overview of these features a system of General Railway Signal Co. (GRS), as they apply to railroad classification yard five minicomputers are used for retarder control, operations. automatic switching, process control backup, MIS applications, and MIS backup (DiPaola, 1973). 5.4.3.1 I/O Interfaces with External Sensing and Control Devices. The PC computer requires Microcomputers can also be used as independent certain external I/O interfaces for accepting or semi-independent processors completing speci real-time data from wayside equipment, for fic MIS tasks in the yard. On-line decision and example, switch detectors, weigh scales, and planning aids are especially adaptable to radar units. The PC computer is' also required microcomputers. With use of an independent com to send out' instructions -to the control equipment puter, speedy response times can be maintained for switches, retarders, and the hump. without affecting total MIS throughput. Deci 'sion aids are also sufficiently independent of The output from field sensors is usually in other applications to permit their development analog form; for example, the passing of an axle and execution on a separate computer system. An over a set of wheel detectors in a certain example is Union Railroad's Yard Crew Management direction causes the sensor unit to emit a level System, which uses two independent minicomputers. of DC voltage (vnc) within a-~predesignated range (for the other direction, the voltage output Inexpensive microcomputers allow not only the would be within a different range). The absence development of new applications, but also the of a car produces a zero VDC. Typically, these use of computers in new locations. Installation analog signals are first channelled into a multi of computers in smaller yards and agent offices plexer and then sent through an A-to-D converter. will soon become economically possible, with the The digitized data are then read into the PC use of smaller independent MIS systems or of computer for further processing. intelligent data entry terminals capable of com munications preprocessing, data base inquiry, The flow of control signals from the computer to and output formatting. An example is the MOPAC's the field equipment is essentially the reverse, development of a remote job entry (RJE) system that is, the digital information from the com for small yards (one or two tracks) and agents puter goes first through the D-to-A converter, (Lynch, 1977). then through the multiplexer, and finally to the line drivers (or data distributors) for sending 5.4.3 PC Hardware Characteristics to the various wayside control devices. In most cases, a PC system is purchased in a 5.4.3.2 Real-Time Transactions. In railroad hardware, software, and installation package yard PC applications, real-time control implies from a PC systems vendor. Nevertheless, the that the PC computer can complete all activities; goal of this manual is to familiarize railroad it samples field surveillance data, digests these computer system users with the design of PC data, makes control decisions, and sends out con systems so that they will be more knowledgeable trol signals in time to influence- the next cycle in systems design and selection. Thus, this of field operations relevant in maintaining a section discusses important PC hardware char predetermined set of operational objectives. For acteristics, including external I/O interfaces, example, in an automatic switching process, a CPU speed in processing real-time transactions, cycle maybe defined as the elapsed time between communications links to other computers, and a the passing of consecutive cuts at ,a fixed wheel high degree of operational reliability. Applica sensing station. In satisfying this objective, tions programs are the most important PC soft the PC computer requires a high-speed CPU, a ware. They are developed from the user-defined 88 large internal memory, and multi channeled I/O process control applications that require diverse devices. I/O communication requirements and reliability in a hostile environment. Programming is made Another important requirement is a powerful simpler by mocking relay symbology and/or Boolean computer instruction set. It should offer logic; a programmable controller can be program several levels of priority interrupts, including med quickly to replace an existing relay-based the automatic handling of inputs from real-time control system (Coughlin, 1981). Programmable clocks. Instructions should be included to controllers are 'also designed for ease of main allow bit position manipulation and logical tenance (error detection and modularity) and for operations. An additional requirement is that easy interfacing with computers for distributed the PC computer offer a sufficient number of control (Martin, 1981). Programmable controllers parallel registers to permit transfer of the may be suitable for a number of applications, maximum amount of field data within one cycle including process control at remote or satellite time. Computers with cache memories are very yards and the direct replacement of failing or advantageous to PC operators because they permit aged relay-based PC systems in smaller yards. rapid access to contiguous arrays, data files, and programs several times faster than the A number of manufacturers offer programmable con regular memory. This feature can easily apply trollers. In some models, two microprocessors to a computer-controlled humping operation, when are used in the CPU. One efficiently completes all the car records belonging to one train may mathematical and proportional/integral/differ be kept in the cache memory for quick reference ential (PID) functions, while the other acts as and updating purposes. the control executive or sequencer. In another design, dual processors are used for parallel 5.4.3.3 Communications Data Links. A yard PC address selection, memory access, and ALU (arith computer not only is required to communicate metic logic unit) operations. Sixteen-bit micro with field control and surveillance equipment, processors are used in some models both for the but it also should be able to communicate on-line CPU and as independent communications and I/O with other computers (e.g., yard MIS computer or controllers. Modular I/O interfaces give added computers remotely located in other yards or at flexibility to communicate to a wide variety of the railroad headquarters). It also must com devices. municate on a real-time basis with yard area supervisor, .hump control operators, track inven The executive program of the programmable tory clerks, and computer operators. Therefore, controller establishes the sequence of routines the PC computer must use a variety of communica and I/O inquiries. Each I/O device or channel tion interface devices. Such devices include is serviced only once for execution of the modems, line conditioning and equalization equip sequence cycle. This requires that the program ment, multiplexers and concentrators, switching mable controller be fast enough to cycle one ,processors, and communication processors. sequence within the critical time value for any controlled device. For example, if a program The purpose of ·the modem is to modulate and mable controller were used to control a retarder .' demodulate a voice-frequency carrier signal with unit, the controller must cycle through the digital information. The most commonly used executive program fast enough to accurately modems range from 300 bps to 1,200, 2,400, and measure the entrance velocity and control the . 4,800, bps. The obj ec ti ve of line cond i tioning retarder within the required time • i and equalization is to adjust the amplitude , attenuation and envelope delay to within certain Programmable controllers are also adaptable to ranges for a more reliable transmission over the control of processes at remote yards. Com voice-grade data communication lines. Multi munications capabilities allow a programmable plexing and concentration equipment is required controller to act as a slave to a PC minicomputer for dividing a communication link into slices at another site and communicate through telephone (or slots), each capable of carrying information or other communication lines. Although program from a separate source. The slices may be sep mable controllers are available with multiple arated from each other by either time-division processors and more than 48K bytes of memory, multiplexing (TOM) or frequency-division multi the lack of real-time interrupts and flexible plexing (FDM). A switching processor is used to programming capabilities may limit the future switch messages between various types of com use to smaller custom process control applica munications lines and handle various types of tions distributed within the yard or at remote terminals, line speeds, codes, and communication locations until lower cost, standard software as protocols. A communication processor is gen required by railroads is developed. In some erally more powerful than a switch processor in cases, the use of programmable controllers as that it can also handle character assembly, net replacements for existing relay control will work polling and handshaking, message queuing, eliminate the need for a more sophisticated and error detection, error recovery, and code costly process control computer. conversion. 5.4.4 Reliability 5.4.3.4 Programmable Controllers. Recent ad vances in microprocessor technology have spurred Reliability is an important consideration for the development of specialized microprocessor configuration design. For each alternative based control systems. Programmable controllers based on a functional allocation, a number of are microcomputers specifically designed for redundancy methods can be used. As the yard 89 operations rely more and more on. the functions , The cold standby configuration is less compli of the yard computers, their continued operation cated and therefore less expensive than the hot becomes more critical. Perhaps one of the most standby configuration. Although two full-sized striking differences between a yard PC computer computers are used for redundancy, less,switching system and a yard MIS computer, system is in hardware is required for a cold standby system. their reliability criteria. A failure in an MIS Moreoever, the secondary computer need not be computer (whether software or hardware) can idle when the primary is in operation~ ·generally be recovered later, provided that the computer is not used continuously throughout a Santa Fe's Barstow Yard uses a cold standby 24-hour day and 7 days a week. Except for system. PC minicomputers are us'ed: One con on-line data conmtmication with :other computers trols switching, another controls retarding, and or terminals, a failure or shutdown of an MIS the third is a supervisory backup. The backup computer does not render inmediate damage to computer takes data from the other two computers other yard operations. and compares them ·with certain established' tolerance limits. If'the input is found to be In con'trast, the PC computer seldom works .outside those limits, an alarm sounds which alone. Its functions are usually linked with stops the hump operation. The, program to control other yard operations. Intermittent errors or a the process (switching or retarding) of the com complete failure can cause inmediate damage to puter that has failed is 'then loaded onto the t,he yard operation. F:or example, a faulty supervisory backup so that it can. take over that switching or speed control setting may cause ftmction. derailment. A PC computer failure during an automatic humping operation may cause the shut If there is no backup computer (or if both com down of the entire hump, thus delaying the whole puters fail), it is necessary to revert to semi yard operation. The loss of a real-t,ime inven .automatic control. Southern Pacific's Eugene tory r'ecord due to computer failure would also Yard, for example, has 'a relay'backup system": seriously delay the switching and speed control pushbutton, relay routing, and "dial:-a-speed". processes because an accurate and up-to-the control of group retarders via a rheostat on second track inventory is needed for these the control console. Exit speeds of car's from operations. the master retarder are still controlled auto matically, using the cars" gross weights to Before software and hardware configurations are determine the amount of retardation needed designed and selected, a set of reliability (WABCO,1976). . criteria should be developed and hardware/ software failure detection and failure-mode In ".smaller" YATS sites, installation of a m~n~ operation specified. computer is planned to keep an on-line inventory concurrently with the YATS computer. With 5.4.4.1 Hardware Redundancy. A number of faiiure of the primarY,l!,ystem, the computer can methods can be used for increasing the avail be used to print inventory?cards in track~ ability of yard computers, as was. described in standing order. These cars can then be used Section 2.3.9. One is to provide increased for a manual card-PICL system. availability with a backup computer, a secondary system that can .quickly take over at system Santa Fe's Barstow Yard has no backup MIS failure. A backup computer with full redundancy processor. If the computer fails, two high is called a fail-safe system. If the second speed terminals are used for data transmission processor does not have equivalent capacity, it .to the COIN computer at systems central and to is called fail-soft; in this case, when the pri the PC computers. " mary computer fails, the least critical functions must be shed for a degraded operation. These 5.4.4.2 Case Study Example. methods can be further refined by a choice,of automatic or semiautomatic switchover. Process Control--The simplest alternative when .the PC computer at Potomac Yard fails is to The system at West Colton Yard has a hot standby return to the semiautomatic switching system. configuration. Digital inputs from field sensors This does require, however, that' both systems be and controls are transmitted to both the primary kept in operating condition. In this case, a and standby crest control computers. The standby switch list must be printed from the MIS computer receives and retains the car-tracking information and manually entered.. Humping exceptions must as humped records until the primary tmit has suc be manually entered via a CRT terminal to update cessfully transferred the information to the the inventory. Terminal Control Computer in San Francisco. Should the primary computer. fail, the backup can Because of increased use of the hump with a PC take over inmediately. It is never used for off computer, a manual backup may not be sufficient line processing (Williamson et al., 1973). except for short periods and the cost of an inoperative hump is very high. The hot standby configuration is an expensive alternative. It requires two complete computers A failure of the PC computer stops the hUmp and extensive hardware·and software to provide immediately, but its inoperation does not become the automatic switchover. critical for a n~mber of minutes, a"delay often 90 experienced during the normal course of humping • Send advance consists operations. Therefore, a cold standby ,computer • Interchange reports configuration can be considered to be sufficient. • MIS reports A fail-safe configuration is probably best be • Shop reports. cause all the expected functions of the PC computer are critical for yard operations and 5.4.5 Hardware Specifications efficient data transmission to the MIS computer. Hardware specifications define the hardware The secondary computer need not be idle when the requirements for the yard. Potential hardware primary compter is operative. Some thought must and system vendors use them to formulate a be given to which applications it can perform. proposal to present to yard and 'railroad When the primary PC computer fails, the standby management. computer cannot instantly take over 'the current PC functions because it does not have the switch The hardware specification is a document in addi list or the state variables of the current con tion to the functional specification developed trol process in its working storage. It must during the system design phase and the software first unload its non-PC applications and then specification used for program development. For initiate the CPU with PC software and data PC systems, hardware specifications are not as tables. important as functional specifications because the specifics are determined by the ,vendor chosen MIS--Potomac Yard currently has an MIS computer to develop the total system. Hardware specifica configuration consisting of two computers. This tions are more important when a yard is devel system has been developed over a number of years, oping or expanding an MIS computer facility that and a major consideration in the configuration is independent from process control because the selection was the 'software invesCnent in the cur hardware needs to develop additional MIS applica rent system. One process'or is used for external tions are defined. communication with tenants and communication with inquiry terminals. The other is used for the A hardware specification may be in two forms: a current MIS programs. These computers communi performance specification and an equipment speci cate through a direct processor-to-processor com fication. munications channel and share a number of disk drives. Figure 5-12 shows the current hardware 5.4.5.1 Performance Specifications. The perfor configuration at Potomac Yard. mance spec~f~cat~on aescr~bes the volume of pro cessing that will be required from the computer. The MIS functions are not as time critical as Expected files and their sizes must be estimated the PC functions. A number of functions, such to determine the size and type of storage that as tenant communications and receiving yard will be required. In addition, the number and inventory, become critical in a number of hours size of each type of file must be determined, as rather than in number of minutes. In addition, well as the expected number of files that will be other functions"'of the MIS, such as production accessed at anyone time. The frequency of of monthly management reports, are required access is also important for size determination infrequently. Other functions, such as some and selection of medium type. Files that are inquiries, although frequent, are not critical often accessed, such as inventory files, must to yard operations. reside on a quickly accessible medium such as hard disk, whereas records that are kept only Potomac Yard personnel believe that neither for historical purposes may be stored less computer is used fully. Therefore, the avail expensively on removable disks or tape. ability of critical MIS functions can be im proved by designing software to provide for Determination of the size of the CPU is based on fail-soft recovery for a processor failure. estimates of program sizes. The frequency of With this design, when one computer fails, the use and frequency of simultaneous use of pro other continues to process the functions of both grams must be known to estimate the size of the computers. processor. Knowledge of the processing mode (whether a program is off-line or on-line and To properly design this fail-soft system, a interacti ve) is also crucial for se lecting a priority of programs must be made. This lirt processor that can handle the load satisfac will be used to designate the programs ,that will torily. The types of operating systems and use continue to run when one processor fails. One of memory and type of memory accesses are also order of priority might be: determinants of hardware size and are part of a performance specification. • Switch list generation • Receiving yard inventory The volume of outputs is another performance • Receive revised switch list requirement stated in the specification. Esti • Classification yard inventory mates of output volume, frequency, and growth • Inbound program are essential~ Different methods of presenta • Receive advance consists tion, such as CRT terminals, printers, cards, • On-line inquiries external communications, and graphics displays, • Departure-yard inventory require different formatting, I/O channels, and • Outbound train consists response times. The volume and type of inputs 91 constitute a performance requirement simi liar to memory may extend beyond disk units when lower output. Again, estUnates of the volume, fre cost storage, such as tape, is required. quency, method of presentation, and response time are required for performance specifications. Communications requirements and I/O devices also must be specified. Required specifications for 5.4.5.2 Equipment Specification. An equipment I/O devices such as CRT terminals and printers specification presents the actual hardware re are type, speed, location, color or black and quirements. For a yard MIS upgrade or for PC white, graphics capabilities, and print quality. system development, it may specifically identify The frequency and volume of external communica interfaces to existing equipment. If an MIS tions is also specified. The types of channels, computer is required Jor a new facility, complete speeds, priority,and media must :be decided. hardware requirements beyond performance require ments may'have been developed in the hardware System software, especially the type of opera study. ting system, is an important consideration that affects selection of the size and type of all The first basic unit that is specified is the other hardware components. A number of operating central processor. Attributes, of the CPU are systems and multiuser operating systems are size, addres!ling, number of registers, cycle , av'ailable and each require different hardware. tUne, and instructions available. The amount of An'additional consideration is to ensure that storage required is divided between mas~ and any purchased hardware is available with the main memory. The' operating system, programs, software and language's that are expecb:id to be and data must be able tO,fit into main memory, required. This software should be available so the total size is affected by the type of directly from and supported by the hardware operating system. Virtual-memory operating vendor a~d in a standard ANSI version. systems- require less main memory but require that mass memory be an extension of main Additional hardware considerations that should memory. Cache memory ,speeds disk access when be included in' a more detaiied specification are mass memory is used extensively in swapping site requirements and limitations. The expected users and program~ in and out of core '(main maintenance and reli'ability should also be memory) in mUltiprogramming environments. Mass specified, as well as future vendor support. 92 CHAPTER 6: ACQUISITION AND IMPLEMENTATION OF. COMPUTER SYSTEMS 6.1 PROCUREMENT PROCESS select PC systems because the application soft ware provided is the major criterion for selec 6.1.1 Request for Proposal ting a vendor. The development of a successful benchmark test requires several steps. The ·first After software and hardware specifications have is to develop a detailed definition and analysis been developed and approved, RFPs may be issued of the work load for the new system. This must to potential vendors. The RFP should cover the include near-term as well as longer term fore following areas: casts. In the second step, a representative mix of programs to be executed is chosen and the data • Functional specifications. to be processed are determined. The output of these steps must be carefully documented, to • Performance requirements. gether with the proposed techniques to test the operation and to measure response time, turn • Hardware interfaces. around time, and transaction processing rates. • Data storage requirements. A formal test procedure is developed and pre sented to the vendors. This documentation helps • Work load expansi?n capability. to ensure that the vendors' software and hardware are evaluated as consistently as possible. Ven • Location and site preparation. dors, at this time, may request modifications and suggest equipment substitution. Clearly, all • Security. adjustments must be made before the actual test. Often, both a user and vendor representative • Maintenance and availability. measure and record timings. At the end of the demonstration, user representatives meet with • System backup/~edundancy. the vendor to review the test results. • Support by vendor, vendor 6.1.3 Negotiations and Contraciing responsibilities. For large-scale projects, a negotiating team is • Railroad responsibilities. formed consisting of at least a data processing manager, a railroad lawyer (or counsel), and a The RFP for a PC system should also include yard railroad financial officer. Sometimes, one or layout and design parameters, assumptions about more major users are also included. The selec track type and rolling stock, and existing field tion of people for the team reflects the manage and PC equipment (see Exhibit 6-1). ment structure of the railroad and/or yard. After proposals have been received from vendors, The type of contract that is negotiated depends they are evaluated for responsiveness, cost, on a number of factors. Some of these are availability, and the like. In the case of whether the hardware is to be purchased, leased, hardware-only purchases (where software will be or rented and whether the vendor is to provide developed in-house), plans for benchmark testing the hardware and/or software, maintenance ser with responsive vendors are made. vices, and so on. Vendors have standard contract forms, which can be modified: to cover the speci 6.1. 2 Development of a Benchmark Test fic situation.: Modifica.tions are often specified by the project manager and reviewed by the rail A major technique for simulating an application road's lawyer or counsel. The contract should on a computer is benchmark testing. This stipulate the requirements for hardware and soft consists of running ,a mix of user programs that ware, the: details of ,s~te requirements, delivery are representative of the predicted work load on and installation, the documentation (such as a vendor's proposed computer system to validate hardware manuals) and'maintenance to be supplied, system performance. This testing not only the guarantees and limitations on tha manufac determines whether the computer has sufficient turer's liability,· the cost, and methods of capacity for the planned applications, but also payment. Ordinarily, the specifications docu provides information on 'operating costs. mented in the RFP become a part of the final contract. In addition, the results of acceptance Benchmark tests are used more often with MIS tests based on the performance requirements computers because they indicate whether the developed as part of the functional specifica computer selected has the capacity for expected tions should be documented. growth. Benchmark tests are not often used to 93 · EXHIBIT 6-1 RFP SYSTEM SPECIFICATIONS A. General Overview 3. Alarms and reports Goals of yard improvement Expected traffic flow 4. Hardware and communication requirements Performance B. Process Control Maintenance and reliability 1. Yard layout and assumptions C. Management Information System Existing and future yard 1. Functional description Track layout Number of tracks, length Car record description Distance from hump crest to tangent Inventory point Arrival procedures Hump profile (grade) Humping and classification Humping speed. Departure procedures· Inventory reports and inquiries Assumptions about rolling Communications. stock--lengths, rolling resistance histograms, worst-case test (good 2. Hardware following bad roller). Performance Installation and switchover to new Maintenance and reliability system. Backup. 2. Functional description of requirements 3. Security and user access Routing and switching 4. Installation and swiech over Functions Performance--percentage of misswitches. D. Power and Operating Conditions Automatic speed control Functions Power available Performance Environmental conditions Percentage of overspeed couplings Site requirements and limitations (size, Percentage of cars stalled air conditioning, noise control, etc.). Sensitivity of change in rolling resistance during a car's run E. Documentation and User Training Percentage of catch-ups and cornering conflicts. F. Vendor Responsibility G. Railroad Responsibility 94 6.2 SOFTWARE DEVELOPMENT AND TESTING test tasks. This is accomplished by subdividing the acceptance test into functional components 6.2.1 In-House Development and Testing. similar to those in the logical model created in the analysis phase of systems design (5.2.2). If software is to be developed in-house rather For example, for the function of verifying and than purchased from a vendor, detailed design upd·ating an inbound consist. system planners can begin after the final specifications for must review existing and proposed clerical pro software have been approved. This stage varies cedures to create and document test procedures according to the completeness of the specifica for the new software programs. Obtaining reli tions but may include the production of module able test data can be very time consuming but is hierarchy charts indicating control flow among worthwhile because, in addition to being used segments, descriptions of the functions per for acceptance testing, the data can be saved fqnned by each segment as well as definition of and used to test future system modifications. all data inputs and outputs from each segment, and plans for testing the operation of each An example of acceptance testing of software is module. Coding should not begin' until after the as follows. A test inbound consist file would design stage has been completed. reviewed, and be created with intentional errors in data and approved. car order. Incoming waybills. ACI data. or videotape records would be used i~ the test to With detailed specifications, and design, segments modify the existing record. The modified can be coded in parallel. Code reading, where records would then be compared against a pre the logic and fonnat are checked by another pro pared file of corrected consist records. grammer, is a reasonable and effective way to detect most errors-:"particularly when combined Acceptance testing of new hardware must also be with a review by programmers whose work inter conducted. Equipment tests are first performed faces with the module and by the chief of the by the manufacturer, usually on the user's programming team. premises after installation. Plans for the final test must include provisiqn for complete Often errdrs' are uncovered in a series of machine user involvement. Procedures must be developed tests beginning with individual .segment and to report arid act on discrepancies that are module testing and then proceeding to integra encountered. tion testing, system testing, and acceptance testing (see Section 6.3). 6.4 SYSTEM DOCUMENTATION 6.2.2 Adaptation and Testing of Commercial System documentation is developed at various Software Packages stages in the systems design phase (Chapter 5) and in the system acquisition and implementation Because of the variety of operational pracedures phase and continues on into the operations and and system requirements among railroads and management phase (Chapter 7). The functional classification yard'S, a packaged yard· MIS or PC specifications (discussed iri Section 5.2) are system will require some adaptation for any developed into system specifications that give yard. When a PC system package is purchased detailed design for the software programs. as from a vendor, adaptation, installation, docu discussed in Section 5.3.4. The next set of mentation, and limited user training are usually documents to be prepared cover the detailed included in the software cost. The programs structure of the software. whicH includes should be tested with the vendor'S test data set preparing flowcharts and program module before any ·modifications are made. documentation. Because an entire vendor package becomes The final two doc~ments to be developed are available at one time, the testing does not manuals--one for operations and one for users. follow the sequential pattern required for The operations manual shb~ld be ~repared before ·software that is developed in-house. Rather, system testing and installation, and the user the entire system can be tested concurrently. manual shold be completed before user training begins. 6.3 DEVELOPMENT OF ACCEPTANCE TEST Pl.AN. SPECIFICATIONS, PROCEDURES, AND TEST DATA Computer operation manuals describe: (1) daily computer runs. (2) who .provides the input. (3) Acceptance testing, which is the final step who obtains the output, (4) what tapes and disks before system implementation, requires careful are needed and how they are identified. (5) what planning and scheduling. Its components are files are to be used and how long each should be preparation of test specifications (to be saved, and (6) how long each program runs and documented in the contract if the system is how much memory it uses. The computer operation developed by an outside contractor), test manual also contains infonnation on backup and procedures, and development of test data. restoration of files. PC computer operation m'anuals require few procedur~s because PC Planning for the acceptance test is one of the computers are usually dedicated to real-time most important steps in the development process. process control and user and field equipment The acceptance test plan should be dev~loped con communication. Procedures are often limited to currently with the software system. A major part maintenance and file backup and restoration. of the planning process is to identify individual 95 User manuals contain procedures for preparing to ensure that training is completed by the time input and for checking and using output. They the new system becomes operational. contain samples of all forms and reports, with detailed instr,uctions forftheir handling and 6.6 SITE PREPARATION use. They state how to add, remove, or change records. Site preparation considerations include not only the layout of the new system, but also the As the systems development cycle proceeds, docu flooring, environmental specifications, power mentation in the later stages is based to a great requirements, cabling and grounding, and fire extent on that developed in the earlier stages. protection, securi,ty, media storage, and safety. For example, if functional specifications are The co'ntrac t for the purchase of hardware should well prepared, they should provide most of the address many of the requirements for the site, information required for the user manual. such as written environmental specifications (including temperature control,humidity, and The extent of the documentation can vary, depen contaminant level of air) for optimum operation. ding on the size and complexity of the systems to be installed and on management philosophy. Hardware may be required to interface the new For example, in its software development guide computer with the existing computer systems or lines, the federal government specifies up to 10 field equipment. Interface and communications documents for use in very large projects (U.S. requirements will be defined by the vendor but Department of Commerce, 1976). A data require purchase and installation may be the responsi ments document is separate from the functional bility of railroad purchasing. Establishing the specifications document~ System specifications interface to the field equipment may be the most in the government system may comprise three complicated because field equipment requires an separate documents--one covering the system/ analog-to-digital and digital-to-analog conver subsystem, one covering the program, and one sion for communication. covering the data base. In addition to a user, manual and an operation manual, a program main The addition of a PC system to an existing yard tenance manual is sometimes produced, as is the may require more field equipment. Additional separate formalized documentation of a test plan presence detectors and/or wheel counters may be and at least an informal test analysis. required for car tracking and counting and for rollability estimation. Distance-to-couple track 6.5 USER TRAINING circuits may also be installed in classification tracks to return distance-to-couple information Part of the process of installing a new or modi to the speed control function, the track overflow fied system is training or retraining the users alarm routine, and MIS inventory records. This in the yard, the DP operators, and programmers. equipment can be installed track by track in a The provision for training depends on a number phased cutover by track group. This will ensure of factors, such as whether the system is new or that a minimum of cars are affected by the clo modified (and the extent of the modification) sure of classification tracks. Each new device and whether the software has been developed will in turn be connected to the PC computer. in-house or purchased. Vendors can be helpful in providing assistance Some of the user training can be a by-product of during the site selection, design, and prepar the acquisition process. For example, the func ation phases. Because the purchase of a new tional specifications are promulgated to advise system may require erection of new buildings or the users of how the new (or modified) system extensive renovations of old buildings, detailed will affect them, and, as noted in Section 5.1.1, planning and scheduling are mandatory. In d~ staff members as well as user supervisors are ciding the physical placement of equipment, for expected to work with the project team. Small example, planners must take operational and main modifications to existing MIS programs require tenance considerations into account. Clearly, only in-house training. Training and new pro the possibilities for future expansion must also cedure documentation should be provided for each be addressed. Even the ordering ~nd delivery of employee who may be required to use the new MIS supplies such as magnetic disks can be critical functions. Training materials can be obtained in effecting an orderly system transition and by modifying the functional specification and on-time project performance. system design documentation. If additional hard ware or operating system programs are purchased, If in-house expertise is not available or addi the supplier will in most cases offer preprepared tional expertise beyond that of the vendor is documentation. If a complete custom software required for site design and preparation, an package, such as PC applications, has been pur outside consultant or engineering firm can ,be chased, training should be provided for a few contracted to provide assistance. In addition personnel who, using the vendor's training docu to, or instead of, a consulting arrangement, a mentation and procedures, can train others in facilities maintenance engineer may be hired to the yard. be responsible for maintenance and operations after acceptance testing is completed at larger A training plan should be carefully documented, EDP facilities. indicating the users who require the training, the content of the training, and the time required for the training. Such planning helps 96 6.7 SYSTEM CONVERSION system and passed through an analog-to-digital converter to the PC computer. In each case, the Several methods of effecting system conversion PC computer is connected in parallel with in are available. One is to use a parallel opera coming field sensors and equipment signals. tion, whereby both the new and the old system These signals are used to drive simulated output are run concurrently while outputs of the new from the computer. The simulated output signals system and old system are compared to increase from the PC computer are compared with actual assurance that the new system is performing and expected output signals as a test of the new properly. At the other extreme, a complete system. Once the simulation shows that the PC cutover to the new system is made after exten computer works correctly for a particular part of sive system tests. This method has risks but, the yard, actual tests can be run. The existing if it is well managed, can be the least expensive relay PC system is used as a safety backup while of the available alternatives. These methods the new computer system is being t~sted. Once assume that both old and new systems perform parallel simulation and actual tests are com similar functions and can be compared. pleted, the existing relay-based PC system can be phased out by disconnecting it from the field By combining these two methods in a "phased" conununications. cutover, only parts of the system are converted at a time. Some parts may be converted in a 6.8 ACCEPTANCE TEST AND SYSTEM INSTALLATION parallel mode, whereas others may be converted without recourse, depending on the complexity For both new and modified facilities, software and other factors that affect the individual and hardware should be thoroughly tested for components. acceptance before they are used for actual full-time operations. All acceptance tests are At times, emulation or simulation may be used to performed in accordance with the test plan and assist in converting from one system to another. specifications in the contract. Test results These processes enable the cutover to proceed should be documented, as should corrective more slowly than would otherwise be possible. measures that have been taken. User acceptance and approval should also be formalized. For safe and efficient conversion from an ex isting PC system (relay base or other) to a PC Testing PC software before system installation computer, parallel operations are suggested. In is often infeasible when it is being added to an turn, the speed control function and automatic operating yard. A gradual phased conversion can switching and routing function must be installed. be used in the acceptance test. As each part of For example, incoming signals are tapped from the system is tested and successfully cut over, the input junction of the existing relay PC acceptance is acknowledged by the yard. 97 CHAPTER 7: OPERATION AND MANAGEMENT OF COMPUTER SYSTEMS 7.1 COMPUTER PERSONNEL ORGANIZATION administrative authority over the EDP operating organizations, its opinions and recommendations The organization of personnel for computer sys to the top management may significantly affect tems operations and management depends, among the direction and scope of the EDP activities. other factors, on whether the system ~s cen tralized, regionalized, or decentralized. It The responsibilit~ and authority for EUP also depends on the number and size of the yards functions between the yard and the company in the system; whether the system covers MIS or central facility may vary from company to PC applications, or. both; and the comp lexi ty of company. In general, the following functions the new sys tern. are viewed as the primary responsibilities of the central EDP department in a centralized The EDP organizational policy varies from organization: railroad to railroad. Larger railroads with a sizable network of yards and rail links tend to • Establish EDP goals and objectives. centralize their EDP functions at the corporate headquarters (or regional headquarters in a few • Assume responsibility for corporatewide cases). The yard EDP personnel in these rail design and development of EDP systems. roads are either under the control of the cor porate data processing vice president (if they • Develop and maintain common standards, are assigned to yard MIS functions) or the policies, and rules. corporate vice president for engineering and signaling (if they are assigned to yard PC • Assume responsibility for centralization functions). The yard EDP personnel under cor of hiring, training, and cross porate control are primarily responsible for utilization of capabilities. systems design and implementation, and their objective is to maintain corporatewide standards • Provide applications analysis and and eliminate unnecessary duplication of effort coordination and software design, between yards. However, other EDP personnel development, and maintenance. also are users of the systems, responsible for carrying out the yard EDP operation as directed • Select and procure hardware. by the yard superintendent. • ~stablish data communication interfaces. Under a decentralized arrangement, the yard EUP functions are more independent than under the • Provide computer operations and services centralized arrangement, and the EUP personnel at the central EDP location--for located in the yard are under the direct control example, waybill processing, customer of the yard superintendent. They also serve as records, accounts payable, payroll, a liaison between the corporate EDP and the yard. general accounting, personnel record processing, inventory and property In railroad companies whose business is primarily accounting, research and engineering, derived from yard operations, the yard superin and systemwide MIS. tendents often have complete control over the yard EDP functions, including computer systems • Balance demand and supply in EDP work design, systems development, equipment selection, load among yards. and operational control. The corporate EDP per sonnel, in this case, serve as consultants and • Maintain proper interface between yards liaisons between the yard EUP and corporate EDP and between yards and central. departments. • Provide EDP consulting services for Regardless of whether they are performed by the yards. central EDP personnel or by the field EUP per sonnel, the EDP functions eventually affect the Assuming that some computer equipment (from a operation of the entire railroad. Consequently, "smart" terminal to a full-fledged computer the EDP groups in many railroad companies are center) is installed in the yard, the respon under the scrutiny and guidance of a companywide sibility of the yard personnel would then EDP advisory committee. The members of the encompass: committee usually represent a cross-section of the company,· including the executive office, • Day-to-day operational functions. marketing, finance and accounting, research and planning, signal and engineering, train control • Hardware maintenance. and operations, and yard management. Although the EDP advisory committee may not have direct • Input data acquisition and preparation. ~------~ 99 l Preceding page blank i -----~,------_.J • Output data dissemination and· • Computer center administrative utilization. specialists. • Coordination with central EDP and other • Software system designers. yards. • System programmers. • Local modifications from corporatewide standard packages. • Applications analysts. • Provision of local operational expertise Applications programmers. to central staff in EDP design and • development work. • Applications consultants. In some areas, the responsibility and authority • Computer operators. are not clearly divided between the central and the field. Some examples are: • Maintenan~e specialists. • Designing and programming of yard • Key entry operators. management decision models, for example, dynamic track assignment, crew • Process control/real-time application dispatching, engine dispatching. specialists. • Modification of parameter values and • Software l~brarian. weights of objective functions in these decision models. • Computer architecture specialists. • Modification of standard software • Data communications specialists. packages to make them more compatible with local applications. Because the EDP field is growing so rapidly, many railroad companies are having difficulty in re • Maintenance work on yard computer cruiting and retaining qualified computer person software. nel; this is even more difficult for classifica tion yards. The major reasons apparently are the In most railroads, the MIS function is the following: responsibility of an EDP department. In most larger organizations, an EDP operations manager • Labor union agreements and company reports to the data processing manager, who has personnel policy tend to limit the types other management responsibilities, such as those of computer personnel who can work in, a for systems analysis and programming. The opera classification yard. Therefore, the EDP tions manager, particularly in a centralized job classifications available in a yard system, is likely to have responsibilities other are not attractive to the regular job than those related to the classification yard; seekers. for example, the manager may be responsible for a systemwide MIS computer operation. • With certain exceptions, the remoteness of the classification yard from urban Usually, the EDP operations manager has respon centers, where most computer people ar,e sibility for the MIS computer facilities as well trained and employed, tends to limit the as the hardware, software, operating procedures, yard recruiters' access to the EDP and data files. The overall PC responsibility personnel supplier market. is usually assigned to the company-level signal and/or engineering organizations. The signal However, this trend at classification yards may division frequently handles PC hardware selection very well change in the future as more and more and procurement, software development or procure yards install sophisticated computer systems. ment, operational design, and so forth. However, Thus, more interesting and challenging work in the day-to-day computerized PC operation in the the f~ture may be offered in the yards rather yard is controlled by the yard management. In than in the corporate headquarters. some cases, the yard is also responsible for com puter programming, wiring of hardware interfaces, One solution to the recruitment problem used by and the development of control and data reduction many railroad companies is to select potential logics peculiar to that yard. The responsibility EDP candidates from the ranks of career railroad for PC software.and hardware maintenance may be employees occupying non-EDP positions 'and train contracted to the system vendor. In other cases, them to be computer specialists., Developing EDP on-site responsibility for the hardware may lie expertise in a person with a railroad background with the EDP department because expertise is generally takes less time than familiarizing an readily available. EDP professional with railroad operations. More over, an EDP professional from the railroad is 7.2 RECRUITMENT AND TRAINING OF PROFESSIONALS more likely to stay with the company because he or she may already have established a career, The types of computer professionals that,' are re within the company. quired to run the EDP operations of a railroad company include the following: 100 The training of yard EDP personnel is usually fails. Such documentation may include lists of divided into two stages. During the first stage, causes and solutions for problems that may be trainees receive formal training and orientation encountered. designed and administered by the corporate EDP organizations. The purpose of this stage is to Many hardware vendors can provide diagnostic ensure that the trainees understand corporate programs to isolate a problem before a service wide standards and procedures. In the second engineer is called. This is particularly stage, the new tDP professionals receive specific valuable at remote yards. If a programmer or training in the yard on all aspects of yard user first attempts to isolate the problem and operations and some in-depth on-the-job'training can obtain advice by telephone from the vendor, in yard EDP operations. many unnecessary and costly service trips can be avoided. 7.3 OPERATING PROCEDURES Good maintenance practices dictate that a log be For the efficient management of a large yard ED¥ kept of systems failures, specifying the date, facility, complete operating procedures must be equipment, problem, cause, and solution. This developed for job flow, data preparation, data log can assist in identifying causes of future entry, computer operations, and quality assur maintenance problems and also identify equipment ance. Establishment of file inventory procedures that has frequent maintenance problems. and procedures for file retention and backup is also important. Because magnetic tapes and disk Large railroads with complex software programs packs can easily be damaged or destroyed, the may also have detailed maintenance manuals that operations manager must establish retention and include program descriptions, as well as descrip backup standards and procedures. tions of the hardware, the support software, and the data base. Maintenance procedures are speci The trend ,has been away from "open shops" where fied that include programming conventions, veri programmers, computer users, and others can fication procedures, error correction procedures, wander freely in and out of computer facilities. special maintenance procedures, and lists of the As computer operations have become larger and programs and flowcharts. Such manuals are par more complex, many computer centers are adopting ticularly valuable in facilities where turnover a semiclosed or,closed site. A closed shop is rates are high. more efficient because computer personnel are protected from outside interruptions, and 7.5 METHOD OF DAY-TO-DAY MONITORING AND CONTROL security is very important. Thus, the closed shop is more cost-effective, more productive, Day-to-day monitoring .and control of an EDP more accurate, and more secure. Other advantages facility is the responsibility of the operations include a clear-cut division between the end of manager or equivalent. Many methods are used to program design and beginning of operations, with successfully accomplish these functions, in a concomitant requirement for more complete and cluding using various performance measures, job clear document'at ion of programs. accounting, and hardware and software monitors. 7.4 SYSTEM MAINTENANCE Performance measures ideally are incorporated into the system during the design phase of the System maintenance encompasses both hardware and project, with special attention given to those software. Contracts often specify vendor respon aspects of the system that most affect produc sibilities for hardware maintenance. Railroads tivity. The most universal performance measures have tended to use this option because PC com used to assess on-line systems are: puters and decentralized MIS computers are usually small and often at remote locations • Terminal response time (time from incapable of supporting a full-time maintenance message transmission to receipt of technician. Specialized vendor maintenance result). personnel are often required to repair problems with field equipment and hardware interfaces • System availability (usually measured as unique to PC systems. Sometimes, it is advan total scheduled availability less down tageous to contract for third-party maintenance- time divided by total scheduled particularly if hardware has been purchased from availability) • more than one vendor. Nonetheless, most larger centralized EDP facilities have at least some • Transaction volume (number of trans railroad personnel who are capable of handling actions in a specified time period). minor maintenance problems. Although job accounting (log-in time for specific All facilities require a preventive maintenance jobs) is effective for evaluating performance of program. This is particularly important for PC batch processing systems, it is seldom used to computers because their failure impedes all yard measure the performance of on-line systems, and operations. Often, weekly scheduled maintenance most new railroad information systems are on-line is arranged to be performed by the vendor--either systems. as a free service or for a fee. Manuals provided by the vendors specify what maintenance is re Hardware and software monitors are often recom quired. Written procedures should be generated mended as, perfonnance evaluators for certain internally that specify what to do if the system operating systems or applications. However, 101 except for terminal response time, hardware Performance monitoring is particularly important monitors are not equipped to measure application because yard applications must interface with performance, which is of most importance in real-time events. One measure of the perfor classification yards. In addition, hardware mance of an MIS computer is whether inventory monitors are expensive and require people with transaction processing can keep pace with actual highly specialized skills to analyze the data. events. The lag between physical events and the Stopwatches, although not as accurate as hard change in the MIS inventory data base reflect ware monitors, can often provide sufficiently the load on the computer if all input has been accurate data to measure terminal response time. made promptly. Occasionally, MIS processing delays may be acceptable if humping does not Software monitors are not as expensive as depend on inventory information. On the other hardware monitors, and their use is much more hand, promptness is much more critical for PC widespread than that of hardware monitors. applications. PC commands for speed control Software monitors can be used to collect data on must be completed in milliseconds for the proper the performance of on-line system functions and operation of field equipment. applications. 102 REFERENCES AND BIBLIOGRAPHY Allman, W. P. "Computer Assistance for Real-Time· Becker, H. B. "Let's Put Information Networks Planning of Yard Operations." Bulletin . into Perspect1ve." Datamation, vol. 24, IRCA: Cybernetics and Electronics on the no. 3, March 197B, pp. Bl-86. Railways. International Railway Congress Association: Brussels, Belgium, February Bl umenthal, M·. '~endors: 4300 Means User 1968, pp. 75-79. 'RelieL" Computer World, February 5, 1979. Amdahl, L. "The Technology Swirl." Datamation, Boeing Computer Services, In~. Making It Count. vol. 24, no. 12, November 197B, pp. 18-20. Vols. I and II, Boeing Computer Services, Inc., 1974. Anderson, 1. E. "Union Pacific's Terminal Infor mat ion Sys tern. II' Papers and Conuni t tee Business Week. "No Boom for Bubble Memory." Reports Presented at the 1977 Annual Business Week, May 4, 1981, pp. 152-153. Meeting. Association of American Railroads, Data Systems Division: Carlin, B. J. "A Status Report on Waybill Data Washington, D.C.; 1977, pp. 49-50. Exchange." Papers and Cormnittee Reports Presented at the 1979 Annual Meeting. Auerbach Publishers, Inc. "Structured Analysis." Association of American Railroads, Data Information Systems Analysis Methods and Systems Division: Washington, D.C., 1980. Tools. Publ. No. 32-04~03~ Auerbach Publishers, Inc.: Pennsauken, New Jersey, Chamberlain,. H. L. "Application of Mini.,. 1979. Computers on the Missouri Pacific." Bulletin 643, American Railway Eng'ineering Auerbach on the Supercomputers and Association: Chicago, Illinois, 1973. Array Processors. Auerbach Publishers: Pennsauken, New Jersey, 1981. Champine, G. A. "Six Approaches to Dis tributed Data Bases." Datamation, vol. 23, no. 5, Data. Process ing Management. Vol. 'May 1977, pp. 69-72. 1, Auerbach Information Management Series. Auerbach Publishers, Inc.: Pennsauken, New ''What Makes a'System Reliable?" Jersey. Datamation, vol. 24, no. 9, September 1978, pp. 195-206. Systems Development Management. Vol. 2, Auerbach Information Management Coleman, S. "SEL Brings Out 'Most Powerf"i.ll' 32- Series. Auerbach Publishers, Inc.:· Bit Mini." Computerworld, "May 11, 19B1. Pennsauken, New Jersey. Computing Surveys, vol. 10, no. 3. Associati'on Data Center Operations Manage for Computing Mac'hinery, i"nc.: New York, ment. Vol. 3, Auerbach Information September 1978.' Management Series. Auerbac'h Publishers, Inc.: Pennsauken, New Jersey. ,Computer, vol. 13, no. 4. IEEE Computer Society, Long Beach, California, April 19BO. Auerbach Reporter. "Computer Technology Fore . . . . cast--Part 1." Auerbach Reporter, Computer Couger, J. D., and McFadden, F. R. Introduction Technology Edition, February 1978. to Computer Based Information Systems. John Wiley and Sons, Inc.: New York, 1975. "A Practical Guide to Distributed Processing." Auerbach Reporter, Computer Coughlin, v. "Selecting an Intelligent PC~I' Technology Edition, September 1979. Design Engineering, vol. 52,' no. 4, April 19B1. "IBM Revolutionizes the Computer Industry." Auerbach Reporter, Computer Datamation. '~ews in P~rspective, Refresh Your' Technology Edition, April 1979. Memory." Datamation, June 1981, p. 78. "Ethnotronics--The 'Shape of Things' DeIvernois, P. J. "Ev,olution of Automatic Con to Come?" Auerbach Reporter, Computer trols in the Classification Terminal Technology Edition, January 19BO. Area." Paper presented at IEEE Annual Convention, March 21, 1972, New York; , Bard, Y. "The VM/370 Performance Predictor." reprinted in Bulletin 282, WASCO: ACM Computing Surveys, vol. 10, no. 3, Swissvale, Pennsylvania. September 1978. 103 Digital Equipment Corporation. Program Demon Hermann, D. J. "SCERT, A Comput,er Evaluation stration: The Missouri Pacific's Yard and TooL" Datamation, vol. 13, no. 2, Terminal System (YATS). Digital Equipment February 1967. Corporation, 1975. Hodges, D. A. "Microelec tronic ,Memories." Dikinson, J. Union Railroad--Computerized Crew Scientific American, vol. 237, no. 3, Management System, A System Overview. September 1977, pp. 130-14). Bessemer and Lake Erie Railroad, October 1979. Huskey, H. "Computer Technology." Annual Review of Information Science and 'Technology, vol. DiPaola, J. J. "The Distributed Computer System 5. Encyclopedia Britannica, Inc~: . in Classification Yards." Bulletin 643, Chicago, Illnois, 1970. American Raitway Engineering Association: Chicago, Illinois, 1973. Isenberg, E. J. "Elimination of Paper Inter change Reports." Papers a~d Committee Ein-Dor, P. "A Dynamic Approach to Selecting Reports Presented at the 1977 Annual . Computers." Datamation, vol. 23, no. 6, Meeting. Association of American June 1977, pp. 103-108. Railroads, Data Systems Division: Washington, D.C., 1977, pp. 73-74. Flynn, M. "VLSI: The Next Computer Generation." ~T~h~e~S~t~a~n~f~o~r~d~E~n~g~i~n~e~e~r, Fall/Winter 1979, Johnson, D. L., and Steiner, F. T. "Process pp. 19-24. Control Computer Systems for Railroad Applications: Site Preparation and Gabet, J. M. "VLSI: The Impact Grows." Data Maintenance Considerations~" Bulletin 327, mation, vol. 25, no. 7, June 1979, pp. WABCO, Union Sw.itch and Signal Division: 108-112. Swissvale, Pennsylvania, May 1978. Gildersleeve, T. R. Data Processing Project Man Karvwatt, R. C. "The Use of Digital Computers in agement. Van Nostrand Reinhold Company: ·Yard Switching and Terminal Operations." New York, 1974. Bulletin IRCA: Cybernetics and Electronics on the Railways. International Railway GRS Co. "GRS Automatic Switching for Car Re Congress Association: Brussels, Belgium, tarder Yards, Circuit Description and February 1968, pp. 80-84. Maintenance." Pamphlet 933, General Railway Signal Co.: Rochester, New York, Kenney, D. P. Minicomputers. Amacom: New York, December 1957. 1978. "GRS Distributed Computer Sys Kurka, F. "Judging the Superminis on a System terns." GRS Deve lopment D21. 0200, General Basis Is Imperative for Full Use." Railway Signal Company: Rochester, New Computer Business News, December 25, 1978. York, October 1971~ Laden, H. N. "Process Automation and Management "CABMATIC: GRS Automatic Cab Sig Control in Yards and Terminals." Bulletin nal System." Pamphlet 1582, General IRCA: Cybernetics and Electronics on the Railway Signal Company: Rochester, New Railways. International Railway Congress York, May 1977. Association: Brussels, Belgium, February 1968, pp. 69-75. "Class-Matic Mark II, Total Auto matic Freight Classification." Bulletin Lay, N. J. "Grand Trunk Westerq Railroad Co. 206, General Railway Signal Company: Train and Yard Planning." Papers and Rochester, New York. Committee Reports Presented at the 1979 Annual Meeting. Associatori of American Graziani, J. M. "Conceptual Approach to Yard Railroads, Data Systems Division: Systems." Papers and Committee Reports Washington, D.C., 1980, pp. 106-134. Presented at the 1977 Annual Meeting. Association of American Railroads, Data Lister, A. M. Fundamentals of Operating Systems. Systems Division: Washington, D.C., 1977, The Macmillan Press, Ltd.: London, 1975. pp. 38-48. Long, P. L. "Computer Technology--An Update." Hall, 1. B. "ICG's Interchange Continuity System Annual Review of Information Science and (ICS)." Papers and Committee Reports Technology, vol. 12. Encydopedia Presented at the 1979 Annual Meeting. Britannica, Inc.: Chicago, Illinois, 1977. Association of American Railroads, Data Systems Division: Washington, D.C., 1980, Lundell, E. D. "Forecast for the 80's: IBM pp. 196-198. Control Systems with More Functions." Computer World, February 19, 1979. Hartman, W., Matthes, H., and Proeme, A. Manage ment Information Systems Handbook. McGraw- Hill Book Co.: New York, 1968. 104 Lynch, P. A. "Small Yard Support System." '~trawberry Yard--One for Five in Papers and Committee Reports Presented at Louisville." Progressive Railroading, the 1977 Annual Meeting. Association of October 1977. American Railroads, Data Systems Division: Washington, D.C., 1977, pp. 70-72. Railway Gazette. "Mar'shalling Yard Control Using Punched Cards." Railway Gazette, January Martin, E. A. "Programmable Controllers--An 15, 1965. Alternative to Computers for Process Reynolds" C. H. "Issues in Centralization." ControL" AIlE News, Computer and I)atamation, vol. 23, no. 3, March 1977, pp. Information Systems, vol. 15, no. 4. 91-98. American Institute of Industrial Engineers, Inc.: Norcross, Georgia, Spring 1981. Sargent, G. A. "Railroad Freight Movement--Some Ne~ Con~ept8 and Current Plans;" Martin, J. Programming Real-Time Computer Sys Transportation Engineering Journal, vol. terns. Prentice-Hall, Inc.: Englewood 100, no. TE2, March 1974, pp. 475-487. Cliffs, New Jersey, 1965. Sayers, A. Operating Systems Survey. Auerbach Design of Real-Time Computer Sys Publishers: Pennsauken, New Jersey, 1971. tems. Prentice-Hall, Inc.: Englewood Cliffs, New Jersey, 1967. Scherr, A. An Analysis of Time-Shared Computer Systems. Massachusetts Institute of Principles of Data-Base Manage Technology Press: Cambridge, ment. Prentice-Hall, Inc.: Englewood Massachusetts, 1967. Cliffs, New Jersey, 1976. "Distributed Data Processing." Martin, J. R., and Durand, S. C. "Implementation IBM Systems Journal, vol. 17, no •. 4, 1978. of a Distributed Computer Complex in Sheffield Yard." Fourth International Schiller, D. E. "System Capacity and Performance Symposium on Railroad Cybernetics, Evaluation." IBM Systems Journal, vol. 19, Washington, D.C., April 21-26. Associaton no. 1, 1980. of American Railroads: Washington, D.C., 1974, pp. 30-41. Schultz, B. "The Year of the Superminis." Com puter World, February 12, 1979. McClellan, T. C. "Frisco's IBM 3790 I)istributed Processing Control Concept." Papers and Shaw, J. C., and Atki~s, W. Managing Computer Committee Reports Presented at the 1977 System Projects. McGraw-Hill Book Annual Meeting. Association of American Company: New York, 1970. Railroads, Data Systems Division: Washinlton, D.C., 1977, pp. 51-56. Southern Pacific. "This is Southern Pacific." Southern Pacific Bulletin, vol. 57, no. 5, McGlynn, D. R. Distributed Processing and Data June 1973. , Communications. John Wiley and Sons, Inc.: New York, 1978. Stein, D. L. "Price/Performance, Semiconductors , ' and the Future." Datamation, vol. 25, no. ;'Myers, G. J. Advances in Computer Architecture. 13, November 25, 1979, pp. 14-20. " John Wiley and Sons, Inc.: New York, 1978. Steiner, F. T., and Johnson, I). L. "t>rocess Noyce, R. N. "Microelectronics." Scientific 'Control Computer Systems for Railroad American, vol. 237, no. 3, September 1977, Applications, Site Preparation and pp. 63-69. Maintenance Considerations." Bulletin 327, WABCO, Union Switch and Signal Division: Page-Jones, M. The Practic'al Guide to Structured Swissvale, Pennsylvania, May 1978. Systems Design. Yourdon Press: New York, 1980. Thurber, K. Large Scale Computer Architecture. Hayden Book Co.: Rochelle Park, New Petracek, J. J. et al. Railroad Classification Jersey, 1976. Yard Technology: A Survey and Assessment. Prepared under Contract DOT-TSC-968, U.S. Townsend, D. F. "Systems Analysis: Key to the Dept. of Transportation, Transportation Future." Datamation, vol. 26, no. 10, Systems Center. SRI International: Menlo October 1980, pp. 145-148. Park, California, July 1976. U.S. Department of Commerce. Guidelines for Progressive Railroading. "West Colton ••• Southern Benchmarking ADP Systems in the Competitive Pacific's New Pivotal Yard." Progressive Procurement Environment. Federal Railroading, September-October 1973, pp. Information Processing Standards Publ. 58-64. 42-1, National Bureau of Standards: Washington, I).C., May 15, 1977. • "Communications/Signaling/Computers ----.'''"'M,.-a7"k-e.... ' Barstow." Progressive Railroading, July 1976, pp. 59-60. 105 U.S. Department of Commerce. Guidelines for Whitehead', A. C. "Southern's Sheffield and Documentation of Computer Programs and Savannah Yard 'Control Systems." Papers and Automated Data Systems. Federal Committee Reports Presented at the 1977 Information Processing Standards, Pub1. 38, Annual Meeting. Association of American National Bureau of "Standards: Washington, Railroads, Data Systems Division: D.C., February 15, 1976. Washington, D.C.,' 1977, pp. 57-63. Vacroux, A. G. "Microcomputers." Scientific Williamson, W. V., Nagel, R. C., and Young, F. American, vol. '232, no. 5, May 1975, pp. E. ''West Colton Yard."" Paper presented to 32-40. Annual Meeting .of Communications and Signal Section of the Association of American Van Rensselaer, C. '~entra1ize?, Decentralize?, Railroads, Data Systems Division: New' Distribute?" Datamation, vol. 25, no. 4, York, October 3, 1973. April 1979, pp. 88-97. Wong, P. J., Elliott, C. V., and Hathorne, M. R. Wellman, L. E. "Union Pacific-Santa Fe Paperless Demonstration of Dynamic Track Assignment Interchange." Papers and Committee Reports Program. Phase 1 report for the Presented at the 1977 Annual Meeting. Association of American Railroads,'Freight Association of American Railroads, Data Car Utilization' Program. SRI Systems Division: Washington, D.C., 1977, International: Menlo Park; California, pp. 78-79. June 1979. Wert, C. F., and McGlumphy, G. F. "Total Ter Yourdon, E. "Different Concepts of Reliability." minal Control." Paper presented to the Modern Data, January 1972, pp. 36-42. Annual Meeting of Communications and Signal Section of the Association of American Design of On-Line Computer Systems. Railroads, Dallas, Texas, October 1-3, Prentice-Hall, Inc;: Englewood'Cllffs, New 1968; reprinted in Bulletin 240, WABCO: Jersey, 1972. Swissvale, Pennsylvania. Westinghouse Air Brake Company. "Computers in Railroad Control, The Progress and the Promise." Bulletin 302, WABCO: "Swissvale, Pennsylvania, '1976. 106 APPENDIX A: CLASSIFICATION YARDS AND THEIR OPERATIONS This appendix,* which describes the physical and switch engine accelerates quickly toward the operational characteristics of classification yard and then decelerates. Just before the de yards, provides the necessary background for celeration, a car or group of cars is uncoupled understanding the operational context of yard and the deceleration of the switch engine and computer systems. Those already familiar with the cars coupled to it causes one or more of the yards may wish to omit this discussion. It is uncoupled cars to separate from the rest. This provided mainly for readers who have a computer . pr?cedure is called giving the cars a "kick." background and little experience in yard operations. The switch engine generally continues kicking cars toward the classification tracks until it This is a general overview of the information reaches the ladder track, at which point it flow relating to the movement of freight cars pulls the remaining cars back along the switch through a typical classification yard. Certain lead and resumes the process. The cars and operational details may vary significantl~ be groups of cars that have been kicked travel tween yards. Part of this variance results from along the switch lead and ladder track until the difference in the systemwide information they are switched onto the appropriate classi processing procedures that the various railroad fication track. Switches in most flat yards are companies use. There can even be dramatic dif generally thrown manually. To improve opera ferences in the information-processing procedures tions, the grades of flat yards are often some in other yards operated by the same railroad what saucer shaped so that the cars tend to accu company. mulate in the center of the yard when switching is being done from both ends of the yard. Such A.l PHYSICAL DESCRIPTION OF CLASSIFICATION YARDS gradients also reduce the frequency of cars stopping short on the ladder track or classifi A flat yard generally consists of a series of cation track. tracks connected by a ladder track and switching lead, as shown in Figure A-l.** Most flat yards Hump yards can classify a large volume of cars use the same tracks for receiving, classifying, more efficiently than flat yards. Typically, a and dispatching trains, although many have hump yard has separate receiving, classification, separate receiving and/or departure tracks. and departure subyards; Figure A-2 shows an in-line yard configuration. For classification, a yard engine takes a group of cars from the receiving yard and pushes them over a raised LADDER portion of track called the hump. Cars are TRACK uncoupled at the hump crest and begin to accel errate down the hump grade, thereby separating from the yard engine and the remaining cars. As "'AD ~ CLASSIFICATION TRACKS the cars roll down the hump grade, braking de vices called retarders (see Figure A-2) control ~~------~~ the speed of the cars, and the appropriate SWITCHING switches are thrown to route the cars into the LEAD designated classification tracks. Master, group, and tangent-point retarders are shown in Figure FIGURE A~l. EXAMPLE OF A FLAT YARD TRACK CONFIGURATION A-2, but many other types of retarder configura tions exist, the most common of which is the combination of only a master retarder and group retarders. The car-sorting process requires that a group of cars be pulled out to the switch lead, where the A.2 CLASSIFICATION YARD OPERATIONS The operations in a classification yard are keyed to the processes involved in receiving and break *The material for this appendix draws liberally ing up inbound trains, classifying or sorting from information contained in Railroad Classi c~rs. and making up outbound trains. Figure A-3 fication Yard Technology: A Survey and Assess depicts most of the major processes involved in ment, by S. J. Petracek et al. of SRI (July moving a car through a classification yard. This 1976), prepared for the U.S. Dept. of Trans flowchart indicates that the individual freight portation/Transportation Systems Center under cars usually arrive with other cars on road-haul Contract DOT-TSC-968. trains, transfer trains, or industrial drags and are placed on one of the yard tracks, if one is **In a large flat yard, the "top" half of the available. Most hump yards and a number of flat yard may be configured as in Figure A-I, with yards dedicate certain tracks or groups of tracks the "bottom" half a mirror image. for receiving inbound trains. If a yard does not A-I RECEIVING YARD CLASSIFICATION YARD DEPARTURE YARD GROUP RETARDER TANGENT.pOINT RETARDER , FIGURE A-2. SCHEMATIC REPRESENTATION OF A HUMP YARD have a track available for yarding the inbound or classification process. Car identification train, the train is held on the main line. If and train consist information are also checked the incoming trairi is too long to be yarded on during this walk-by inspection. one track. it is broken up and yarded on two tracks. This "doubling" process requires between The switching or classification process is the 10 and 20 minutes and can often be ,performed by central activity in classification yards. It the road-haul crew, depending on labor agreements involves sorting the cars that have arrived and other considerations. After an incoming grouped on a train or industrial drag into appro road-haul train has been yarded, the locomotive priately assigned classification (or "class") units and caboose are detached and moved to a tracks. The assignment of cars to the classi service area. In some yards, however, the fication tracks is generally based on the cars' caboose is not detached but is actually humped destinations and the sorting policy of the yard. (or switched) and sorted with the rest of the For example, in one yard, all cars bound for cars on the train. Chicago may be placed on Track 9 and all cars bound for Buffalo and Boston may be grouped After the incoming train or drag of cars has together on Track 4. Other track assignments been yarded and the engines and caboose have may be based on the 'condition of the car (such been detached, the air-brake systems on the cars as whether it requires cleaning or repairs). are ready for bleeding. This process is re Cars in transit through a yard often must be quired because, after the engines are uncoupled reswitched or rehumped for a number of reasons. (thereby breaking the air-hose connection), the Fdr example, cars that require special proces individual car brakes are automatically acti sing (such as cleaning or repairing) usually vated by air in the compressed-air reserv~ir. must be reswitched after such processing has Car bleeders must release this reservoir air to been completed. In addition, many yards do not deactivate the brake system so that switch have enough tracks to assign dedicated tracks to engines can freely push cars to the hump or each of th. blocks being made up in the yard. along the switch lead. The air brakes are bled This forces yard personnel to mix 'blocks to by carmen who walk along one side of the train gether on a track and then reswitch these cars and stop at each car to open angle cocks that when a slough track becomes available. release the air. Often, however, the release rod on the carman's side may be broken and he After being switched onto the correct classi must climb or crawl between cars to use the fication traCk, the c~rs generally wait while release rod on the other side. others are being switched. The time that cars spend onia classificatton track waiting for Generally, while the air-brake reservoir is be enough other similarly' b,ound cars to inake a ing bled the individual cars are inspected for train is referred to a~' '''accumulation time." mechanical or physical defects. Some common de fects are dragging equipment; mechanical failure After enough' cars have been accumulated to make a of the air-brake system; cracked or broken train, or according toa departure schedule, they wheels, bearings, and journals; broken couplers; are assembled into a train or industrial drag. door and seal problems; and car structural In this process, the blocks of cars that are on damag'e. Other defects, such as damaged or a number of different tracks are joined together shifted loads, are also identified. After the on a departure track that is long enough to hold "bad-order" cars are identified, they are sorted all the cars for the train; lacking that, many out from the others during the normal switching yards use the main line for making up trains. A-2 DETACH AND SERVICE LOCOMOTIVES YARD INCOMING TRAIN ON A INSPECT CARS SINGLE BLEED BRAKES RECEIVING TRACK DETACH AND SERVICE CABOOSE YARD INCOMING TRAIN ON SEVERAL RECEIVING TRACKS Det=:ision Rule For Pulling Class Tracks SWITCH ENGINE SWITCH ENGINE MOVES TO MOVES CARS TO SWITCH ON - APPROPRIATE SWITCH LEAD OR , HUMP CARS HUMP LEAD :I> ...,I MAKEUP ENGINE MOVES TO APPROPRIATE CLASS TRACK TRACK AESWITCHING. ETC. MOVE CARS CONNECT AND TO APPROPRIATE ATTACH ENGINE CHARGE INSPECT TRAIN DEPARTURE AND CABOOSE AIR LINES TRACK FIGURE A-3. CAR-HANDLING PROCESSES IN CLASSIFICATION YARDS After the cars and blocks have been coupled, Additional information is obtained when the carmen connect the air-brake hoses, turn the train arrives. The identification numbers of brake valves, and inspect for bad-order or the cars in the train are noted and recorded misswitched cars that must be switched out of using closed-circuit television and videotape or the train. After the cars and air-brake hoses aUdiotape or by pencil and paper. These numbers have been connected, the train's air-brake can be checked against the advance consist system is charged. There are three methods for inforation, and corrections .can be made on an charging the air lines. The first, and generally exception basis. Waybills and/or bills of the fastest and most desirable, is to use sources lading also arrive with the train. A bill of of compressed air that are located near the make lading is the agreement between the shipper and up tracks. When such facilities are not avail the railroad concerning the transportation of able, the airing can be done by a switch engine the shipper's goods. A waybill is a receipt or by the road-haul engines after they have been that details the shipment and routing inven attached. The air-brake system is then checked tories. Locally originated traffic is often for leaks. accompanied only by bills of lading, thereby requiring the preparation of waybills; inbound At this time, the power units and caboose are road-haul traffic is generally accompanied only attached and the train is physically ready to by waybills. All this paperwork is the responsi depart. A number of factors, however, can delay bility of the train conductor until the train departure, such as lack of road-haul crew or reaches the yard, at which time a yard office power, lack of paperwork, or interference within clerk assumes responsibility. Waybills are then the yard or on the main line. prepared from bills of lading for those cars that require them and, in some yards, punched This description of the major car-handling pro cards are also prepared. The waybill and the cesses that take place in classification yards other recorded information are then used to has been general in scope and only describes update the advance consist information. From major classification yard operations. Although this enhanced information, classification tracks this description has been organized in a step are assigned and the switch lists are prepared. by-step operational sequence, it is important to A switch list (also known as a cut list or hump note that, in most classification yards, these list in hump yards) assigns a classification operations are performed simultaneously on dif track for each car or cut of cars. ferent cars and trains. While one train is being received into a yard, another train or group of Thus, the actual switching of a train cannot cars may be in the process of being classified, begin until all this information processing has while still other cars are being assembled into been accomplished. A potential for delay there an outbound train~ fore exists if the information processing takes longer than the brake bleeding and car inspec A.3 PROCESSING OF INFORMATION AND PAPERWOKK tion. Slow rates of information processing may also limit the speed of processing high-priority The actual movement of cars through a classifi trains and the effectiveness of certain automa cation yard is usually paralleled by the pro tion features such as high-speed car-inspection cessing of information and paperwork within the systems or automatic coupler and brake systems. yard. In fact, the transference and processing of information is an essential supportive part After the switch lists have been completed, they of the car-classification and train-makeup pro are distributed to the yardmasters, hump foremen, cesses. The purpose of these activities is to retarder operators, switchmen, and the switch obtain a timely and accurate inventory of which engine crews. Any changes are then manually cars are located on what tracks. Without such recorded on the switch lists. An example of information, the classification and train-makeup such a change would be the reassignment of a car processes could not be ade~uately controlled. from a specific classification track to a bad order track because of deficiencies discovered The first information a ya~d receives concerning during the intial car inspection. an inbound train is its inbound consist, which is a description of the makeup of the train. At When the next step in the classification yard most large and medium-sized yards within modern procedures is performed--the assembling of cars ized railroad networks, this consist information from different classification tracks into an out is received before the actual arrival of the bound train--the waybills for the cars on the train. Although this may allow the yardmaster outbound train are also assembled. The car num some time for advance "operational planning, this bers and waybills are compared in an outbound capability is often limited by the quality of check, and the necessary corrections to the the information or the"amount of confidence the consist are made. The waybills are then trans yardmaster has in it. The advance inbound con- ferred to the outbound train conductor. When -sist is the outbound consist of the last yard the train departs, the outbound consist is where the train stopped, and that yard has the transmitted to a centr~l processing location or capability of revising the consist information. to the next yard, where it becomes the advance If the train picked up or set out any cars or inbound consist for the train. blocks of cars after passing that terminal, the advance consist would be in error. Two major types of yard inventory systems are used to monitor car location and track status in the yard: manual and computer inventory systems. A-4 An example of a manual system is the PICL system the corresponding pigeonhole. The computer in (perpetual-inventory and car-location system). ventory system is often referred to as a disc ~n this system, punched cards are produced rep PICL system (as opposed to the manual card-PICL resenting each car. A box (or rack) of pigeon system). The comp,uter system keeps track of car holes is used to represent each track in the location and status as cars are physically moved yard. A yard office clerk, referring to the by appropriately processing computer files. Cars switch list, manually sorts the waybills and usually are moved in the computer according to punched cards into the pigeonholes corresponding the switch list or a prescribed classification to the tracks onto which the individual cars are track assignment table. The computer systems switched. In this system, the waybills and are much faster and more flexible and accurate punched cars follow the physical car movement than the manual systems; they normally can pro from track to track by moving from pigeonhole to vide a track inventory, fin4 the location of pigeonhole. Yard personnel can identify the cars cars, and produce many types of management on any track by look{ng at the punched cars in reports. A-5!" APPENDIX B: CURRENT COMPUTER INSTALLATIONS SURVEY The use of digital computers in railroad yards is presented in the following tables: • Table B.1--Yard Configurations • Table B.2--Computer System Configurations • Table B.3--Periphera1s·Used. These tables are combinations of tables presented in "Computer Applications to Classification Yards," AREA Bulletin 650, pp. 272-:277; and "Railroad Freight Car Classification Yards: Installations, 1978-1924," by WABCO. B-1 1£ I""" ~ H Ie I~ ~ tf.l + :'-' tf.l :~ ,..... I,...., tf.l ""'P-I i ...... 1£ ....:I I,....., t ~ 1...-. ~ en ~ I~ -.-/ :::J .p:; 1£ ~ :e. Table B.l :i IS...., H Q) 0 tf.l 1-;;:: P-I IS U u u lEi I~ ~ Ie ~ Q) ."... 13 I~ 0 0 ip:; 1$ ~ I~ ~ e e ":::J H I~ 4-J ~ P-I 13 en ~ 1£ IS tf.l 0 Q) 4-J Q) ~ .~ -< I~ YARD CONFIGURATIONS ...... ,~ I~ I~ .~ 1£ 13 1'-" I~ '"d I=l 0 H 1';3 ...., '"d 4-J iU Q) !2 en ..-4 ~ § ...., s:: "' Jil I~ 0 tf.l ~ 1-1 U Ie 0 :e. ~ I=l Cl "'s:: -.-/ Ie Q) t:l '"d I~ Q) 4-J ...... 0 Q) ~ "' Q) .~ P-I ~ cu 4-J ; ~ s:: en 1-1 -.-/ M 18 4-J Ie en 0 ~en Q) 4-J t: t:l (I) I=l Q) 0 0 Q) Q) "-l ~ ~ "' 0 .c 0 s:: .c ~ ..-4 4-J ~ s:: ~ . 4-J ~ "'en ~ ~ ~ ,!oI tJ s:: 4-J ~ t-l '0 4-1 U 4-J (I) 1-1 en (I) Z -.-/ 4-J 0 ~ ..-4 tJ en cu 0 ~ (I) 1-1 1-1 tJ 1-1 1-1 ~ ~ ,., (I) ~ ~ ~ :;I lil 0 ~ (I) . ~ .c ~ ....."' r.!l ~ I:Q I:Q I:Q P-I z i<~ ~ P-I I~ u I:Q ~ U 1:;;1 tf.l I~ H I~ I~ tf.l 1;;;;1 I~ I~ 1& I~ i~ I~ "' "' "' .. "' i8 Single Lead-Single Hump X X~ X X X X X X X X X X X X X X X X X X X Dual Lead-Single Hump X X Dual Lead-Dual Hump X * X X Receiving Yard Tracks 5 8 9 7 9:18 ill 7 5 a> 14 ill 3 7 2( 6 9 1 1 24 ~ 12 Classification Yard Tracks 3;! 5) 42:&1 1'it: 42 141: 4C 4 5~ 44 [4E 16 P4 4~ 3~ 51 U a> 63 4~ 64 15e 14E Departure Yard Tracks ~5 8~3 618 15 9 8 5 8 9 .0 4 8 2( 6121 9 14 14 1~ Car Retarder Operator X X X X X X X X X X X X X Ix X X X X Master Retarder Control X X XX X X X X X X X X X X X X X X ~ X X X X X X X XX X X X X X X X to Group Retarder Control· X X X X X X X X X X Ixx X X X X X X X X X I Intermediate Retarder Control X '" X Tangent Retarder Control X X Ix Ix Skate Retarder Control IX X Ix X ~ iK Ix Hump Speed Control· X Ix X Ix Ix Ix Ix Hump Signal Control X XX X X X X X X X X X X Coupling Speed Measurement X X X X X X X Auto Trim, Bi-dir. Track X X X Pull Down Tracking Ix X X Auto Calibration Data Collection X X X X X X X X X X X X X X Computer Simulation X X X X X X Sources: "Computer Applications to Classification Yards," AREA Bulletin 650, pp. 272-277 (1975). "Railroad Freight Car Classification Yards: Installations, 1978-1924," Westinghouse Air· Brake Company, Swissvale, PA (1978). *Layout designed to provide for future dual hump. f Manual control. + Information not obtained yet, .' r,;:;;.; ...... z ILl ,"" H e U) Ii: ,-.. ,8 U) I~ II;-. I- U) p.., ...... , :z H (II ,-.. Ii: u t '<'l I...... ~ ~ '<'l 1,.-., ~ '-" H I...... I"" I U) Table B.2 ~ ~ OM E-4 . 0) 0 p.., z p..,;~ p.., IS '<'l U u u IsIt: I~ .-4 U) :t: «:I 1>1 64K X X X X X I \.oJ Honeywell (H-llS) X X Honeywell (H-S16) X X X X X X GE PAC 4000 X GE PAC 4020 X X X X IBM (S-1800) X X Data General X X X X DEC (PDP 8 and 81) X X DEC PDP 11 X X Kt KiF X+ Xerox (Sigma 3) X Modular Computer Corp (Mod Comp II) X X Sources: "Computer Applications to Classification Yards," AREA Bulletin 650, pp. 272-277 (1975). "Railroad Freight Car Classification Yards: Installations, 1978-1924," Westinghouse Air Brake Company, Swissvale, PA (1978). ° *This refers to memory size for PC except at Sheffield and where PC and MIS are combined. tPDP 11/60. {I PDP 11/34. + Information not obtained yet. ------1£ I...... I;; H Ie ~ U) I'i: ...... U) I~ 18 U) p., I,..., 1£ ...... , f.3 1 t; ~ I'i: I""'" 1.-. ~ en =::> Ip:; ~ ~ Table B.3 < ...... IS ..-l Eo< ,..., QJ 0 Z U) p:; p., p ,.... u u u ~ t! ...... Ie 1.8 QJ 0 1$ I~ I~ I~ 1-;3 Ie is Eo< I~ .j.J ~Iz Ip: "" p., Ip: 1 ~ Ie en ...... ~ 1£ IS U) 0 "" QJ .j.J 0 PERIPHERALS USED ...... I~ If:! til QJ It! 1£ Ie"" til 1'-' IP: "'d (:! 0 Eo< t; 1-;3 1$ "'d .j.J til I~ QJ e en (:! ~ .r-! .!i1 ,.8 ...... 0 U) ~ § 1-4 U :~ 0 ,2 ...... 1.8 (:! d d ..-l '-' QJ 1=1 "'d 1.8 QJ .j.J '-' 0 QJ ) 0 ~ p., ~ QJ 111 .j.J ~ ~ 1=1 111 III 1-4 .r-! ...... 18 .j.J I~ III 0 en QJ .j.J d d ~ ~ ~ d QJ 0 0 QJ 0 QJ .r: 44 0 ..c:: .g ..-l .j.J ~ d ...... j.J ~ III ...... ~ ~ CJ d u ~ o-l "'d 44 U .j.J til QJ 1-4 III QJ ~ z .j.J ~ 0 ...... -l 1-4 CJ III 111 d 0 ...... QJ ~ 1-4 1-4 CJ ...., ...., d :i ~ ..c:: .j.J ~ liN l:;l til Hi l;l I~ I~ I~ 1:1 I~ I~ I] I~ I: I~ I~ IJl ltd I~ I~ 13 I~ til I;Q I~ I~ ;~ 1& I~ I~ Disks X X X ~ pc X X 2 X 2 X 2 2 IX X IX ~Fixed Head Drum X X X X X X X I-Cassettes X Line Printer Ix X Ix X 2 X ~ X Card Reader X X X X X X X X X ~ 2 X X 1 1 X ' If..,. Card Punch X X'X X X XX X X ~ 2 X X 1 1 Cathode Rav Tube (OutPut On1v) 2 3 XX 2 X5 ~ 2 3 4 X 2 Cathode Rav Tube (I/O) XX 3 7 X X 3 2 X 4 I/O Typewriters"; 7 X 4 5 X 5 7 XX 5 5 X X 311.2 X 2 X 3 X 5 3 X 2 X 4' Mag Tape X X s Paper Tape Reader/Punch X X ! I Note It t t 1+ 1+ 1+ 1+ :II ,Z Sources: "Computer Applications to Classification Yards," AREA Bulletin 650, pp. 272-277 (1975). ~m "Railroad Freight Car Classification Yards: Installations, 1978-1924,"Westinghouse Air .~ :I Brake Company, Swissvale, PA (1978). ~ ~ !il -~ *Including "receiving only" TTYs. ~ ~ t '" Does not inc1u~e peripherals for MIS except for combined PC/MIS configuration. '"N N +Information not obtained yet. ~'" -...'".. .1