NOTICE This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Govern­ ment assumes no liability for its contents or use thereof. NOTICE The United States Government does not endorse pro­ ducts or manufacturers. Trade or manufacturers' names appear herein solely because they are con­ sidered essential to the object of this report. T ~chnical Repart Docum~ntotion Poge 1. RopOr! No. 12. G.y.,"~.", Acce",," No. 3. Reciplenl's Colalog No ;- FRA/ORD - 77/37 .II ~b -1-'1 ~~ ') - '?> I 4. Title and Subtitle 5. Reporr Dale INKOVATIVE CONCEPTS AND TECHNOLOGY FOR September 1977 I RAILROAD -HIGH1\'AY GRADE CROSSING MOTORIST 6. Pe,Iorrnlng Organ, 101 on Code' t WARNING SYSTEl>lS Vol. II: The Generation and ~ Analysis of Alternative Concepts 8. Pe,formlng Orgonl10tlon Reperr No. 7. Au1f-or's) : D.O. Peterson and D.S. Boyer DOT-TSC-FRA-76-l9.II 9. Per'OfrT\lng Orgar1l10tio... Name and Address 10. Wor ... Unl' No. (TRAIS) Tracor-Jitco, Inc. RR602/R7337 * I 11. Contract Or Granl No. i 1776 East Jefferson Street : DOT-TSC-842-2 Rockville MD 20852 , 13. l)'pe of Report and Per·cei Covered 12. Spon,oring Agency Name and Addren I U.S. Department of Transportation , Final Report : Federal Railroad Administration June 1974 -ylarch 1976 Office of Research and Development 14. SpanlGring A90ner Code Washington DC 20590 15. Supplemenlary Notes : U.S. Department of Transportation !*Under contract to: Transportation Systems Center I Kendall Square Cambridge t-IA 02142 I 16. Abstroct I This report describes the results of a study directed toward the I generation, analysis and evaluation of innovative conceptual and technical approahces to train-activated motorist warning systems for i use at railroad-highway grade crossings. Particular attention is given to the use of the track as a transmission line in a guided reflection t (radar-like) technique operating at audio frequencies. Attention is also given to improve special road surfaces in advance of the crossing, and to optically programmed traffic lights. Volume I consists of 210 pages. 17. I( IS)' Words lB. Dill,.b",tion Stalement Railroad-Highway Grade Crossings, DOCUMENT IS AVAILABLE TO THE U.S. PUBLIC Grade Crossing Warning Systems, THROUGH THE NATIONAL TECHNICAL Grade Crossing Signal Systems INFORMATION SERVICE. SPRINGFIELD. VIRGINIA 22161 19. Security CIQllif. (of thrl report) 20. Security Classif. (of this p"o;.) • 22. Price Unclassified Unclas s ified Form DOT F 1700.7 (8-72) Reproduction of completed page authori zed ; I PREFACE The work described in this report was performed in the context of an overall program at the Transportation Systems Center to provide a technical basis for the improvement of railroad-highway grade crossing safety. The program is sponsored by the Federal Railroad Administration, Office of Research and Development. This volume, the second of a two-volume report, consists of a report documenting a process of concept generation and evaluation in the field of innovative grade crossing warning systems. Volume I includes an executive summary for the two volumes, an overview of the subject area, and a similar concept study carried out by another contractor. iii METRIC CONVERSION FACTORS App,olim.1t Con••llionl 'A M.uie MIIIU." ::: , App.ill,mu. Con••llionl Ir•• M.,.ie 1 --: M M -: 5,..... • .... Y'I •••• 1101".1, " To fiM s,... .....'.. 1 ... lIolt,,,, " II fi•• S,••ol '.0' -: ;; LENGTH, -= o M lENGTH mllll~llIfS 0,00 .nches --: !: cedl.meler, 0.• In€:he" mele., l.l I .. It .n,h•• ,.S ,.nlure•••s yd It t••• lD ceo,une'.', ~ m.'ers 1.1 , . kIICllNlI... 0.' ml'•• ,d ,..... 0.' "-'.,~ ... mil•• I.' ....IOfIIIII.,' km !: -= AREA AREA --: ::!: -.au-" cenl"'-,." 0.1. ~.Ine"'. ,n' ,n' squIiI'lI squ.r. cenhrne1•• <m' --= J .net-.. '.S ~ m square 'NI'''S 1.2 square y.rd" ,." 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I m' cub.c meier, 31 cubic'''' It' ., _to O.'S Ilief• I m' cub.c meier" 1.l CubiC W..... ydJ .g,\ .., pllonl l .• 1,Ien I ~'" It' cub.c '_I O.Ol cub.(, mel ' m' OJ ' yd' CubiC .....d .. a." cub.<: . m' 'TEMPERATURE t...U) TEMPERATURE (lI.el' ., ·c C.lslus '1&,­ ,......... ., -........ruq _J.l' ........... ~:~:~ ,......... iI' I.". CelllUI ·c I-ms-r.'ure ., DI .... ,- -- 0,. .n .... 212 .~, ~ r~ .~ ~ '~O, '~o ~ - •, II II I , I' III 'c:o ( iii, i ,) 'i i ==----------::. "-40 -20 0 20 40 .0 '0 100 ! ~ ! .c ,1 ·C TABLE OF CONTE~TS Sect ion APPROACH ,. 1 2. CRITERIA . 4 2.1 Operational Applicability in 3 to 5 Years... 4 2.2 Grade Crossing Specificity. 5 2.3 Cost Acceptability.. 5 2.4 Constant ~arning Time....................... 5 2.5 Capability of Integration Into Larger Traffic Control Systems.................. ... 6 2.6 Capability of Continued Operating Upon Failure of Normal POKer Source.. 7 3. CC~CEPT EVALUATION . 8 3.1 Classification of Concepts.................. 8 3.2 Train Detection............................. 8 3.2.1 General Considerations........... 8 3.2.2 Direct Sensing Systems.......... 9 3. 2 .2.1 Radar . 10 3.2.2.2 Se ismic . 10 3.2.2.3 Infrared . 11 3.2.2.4 Acoust ical . 11 3. 2.2.5 Other ~lethods . 12 3.2.3 Sens ing via Track Structure.......... 13 3.2.3.1 Guided Radar . 13 3.2.3.2 S\o,'i tches . 14 3.2.3.3 Airgap Transformers . 15 3.2.3.4 Buried Loop . 16 3.2.3.5 Track Circuits . 16 3.2.3.6 l\onelectrical ~lethods . 17 3.2.4 Train-Borne Systems.... 18 3.2.4.1 Reflect i ve Device . 20 3.2.4.2 Strobe . 20 3.2.4.3 Electromagnet . 20 3.2.5 Communication Systems 1..... 21 3.2.6 Protection and Warning at the Cross ing. ............................ 22 3.2.7 Advanced h'arning Concepts... 25 v TABLE OF CO~TE~TS (CO~T'D) Section 3.2.8 Arresting/Impact Attenuation Devices. ............................. 28 3.2.9 Self-Containec Po"er Sources..... .... 28 3.2.10 Modification of Driver Behavior... ... 29 4. RECmL\lEKDED CO:--JCEPTS . 31 4.1 Train Ranging and Correlation System (TRACS) ..................................... 31 4.1.1 Rail/Ballast System . 32 4.1. 2 System Configuration . 35 4.1. 3 System Performance . 38 4.1.3.1 Range Resolution . 38 4.1.3.2 Integration Time (Maximum) .. 40 4.1.3.3 Transmission Line Equations (Infinite Line) . 41 4.1.3.4 Wavelengths, Wave Velocity, and Signal Attenuation . 45 4.1.3.5 Detention Gain . 49 4.1.4 System Implementation... 58 4.2 Open Graded Asphalt Friction Course......... 66 4.3 Optically Programmed Traffic Signals........ 70 5. COST ANALYSIS . 77 ~~ 5.1 TMC System . II 5.2 Open Graded Asphalt Friction Course . 78 5.3 Optically Programmed Signal Lights . 80 REFEREKCES. ...................................... 87 APPE~DIX A- REPORT OF I~VEKTIO~S 88 vi LIST OF ILLUSTRATIOKS Figure 4-1 ~lodel of Rail/Ballast Structure (dc) : 33 4-2 Model of Rail/Ballast Structure Audio Frequency .... 34 4-3 Ranging Syste8s Configuration for Continuous Steel Rail Application 3i 4-4 Ranging System Configuration 3i 4-5 Definition of Range Segments and Delay Line Tap Output , 39 4-6 Ranging System Signal Processor, ~lodular Construction 39 4-i Transmission Line ~,Iodelled as Iterative Network .... 42 4-8 Single Stage of Correlation Receiver 51 4-9 Simplified TRACS Concept (~o Ballast Compensation). 59 4-10 TRACS Using Digital Delay Compensation 63 4-11 TRACS Using Analog Variable Delay Compensation 63 4-12 Multiple Crossing Control 66 4-13 Open Graded Asphalt Friction Course of Dense ~ix ... 68 4-14 Open Graded Friction Course with Rumble Strip Effect iO 4-15 Optically Programmed Signal Propagation il 4-16 Optically Programmed Signals - No Train Approaching .. , i4 4-li Optically Programmed Signals - Train Detected at a Distance i4 4-18 Optically Programmed Signals - Train Approaching Crossing i5 5-1 Typical Check List for Specification of Grade Crossing Protection 84 vii LIST OF TABLES Table 5-1 ESTIMATED COST OF TRAFFIC COKTROL EOUIPMENT AKD OPEN GRADED ASPHALT FRICTIOK COURSE 'FOR A TWO- LA:-JE SI:-JGLE TRACK CROSSING........................ 81 viii 1. APPROACH In this section we describe the general approach that we undertook to develop solutions to the problem. The specific steps themselves are described in later sections. The guide crossing problem is one of long standing. The last century has seen at least an experimental installa­ tion of a wide range of ideas for improving some aspect of the grade crossing. As in many areas that have been under investigation over a span of ti~e encompassing great tech­ nological changes, failure in a new concept for railroading was as apt to be the fault of experiment design, or lack of suitable materials and hardware to flesh out the bare bones of the concept, as it was to be any fault in the validity of the concept itself. ~e endeavored, therefore, to search the literature not only to achieve an understand­ ing 'of the ~roblem's many aspects, but also to rediscover for new consideration ideas whose earlier nremature birth had precluded survival at that time.