REAL TIME DISPATCHING CONTROL IN TRANSIT SYSTEMS by Wei Song B.E. Transportation Management Engineering Northern Jiaotong University (1993) M.S. System Engineering Northern Jiaotong University (1996) Submitted to the Department of Civil and Environmental Engineer- ing in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN TRANSPORTATION at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY JUNE 1998 © Massachusetts Institute of Technology, 1998. All Rights Reserved. A uthor ................................................. ................. Department of Civil and Environmental Engineering June 18, 1998 C ertified by ................................ .............................. Professor Nigel H. M. Wilson Department of Civil and Environmental Engineering Thesis Supervisor Accepted by .............. ........ ... ------------------. ----.................. Joseph M. Sussman MASSACHUSELOS NSTITUTE Chairman, Departmental Committee on Graduate Studies OCT 2 6 1998 LIBRARIES I I Real Time Dispatching Control in Transit Systems by Wei Song Submitted to the department of Civil and Environmental Engineering in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN TRANSPORTATION Abstract Maintenance of reliable service is a goal of any rail transit agency. Reliability is difficult to maintain due to the perturbations that serve to disrupt headway sequences. These incidents that affect the service quality of transportation agencies can be categorized into two types, major disruptions and minor disturbances, based on their nature and causes. To maximize the capacity of a rail transit line and avoid busing, single track operation is analyzed in this thesis to deal with major disruptions. Based on the tracks and crossover configuration of the Massachusetts Bay Transportation Authority Red Line, a full analysis of possible strategies is presented which might form the basis for a major disruption response system. This could take the form of pre-planned short term operation plans which would be geared to the type, location and time of day of the disruption. The dispatching problem occurs around a terminal when a train is not expected to arrive at the terminal early enough to be dispatched on its next trip on schedule. This problem can be considered as a special case of minor disturbance. Its solution can also supply insight into the more general minor disturbance problem. We use holding and short turning as our control strategies to deal with the dispatching problem. Choosing minimizing passenger waiting time or the number of overcrowded trains as the objective, a heuristic dispatching control model is designed and evaluation and simulation models are used to estimate and compare the effectiveness of the current dispatching system and the heuristic dispatching control model. The results show that the heuristic dispatching control model could produce savings in average passenger waiting time of up to 14%, with the effectiveness increasing as the disruption becomes more severe. As part of this research, a dwell time model is estimated for Red Line trains in order to predict the running time of a train to help select the appropriate control strategy. Thesis Supervisor: Nigel H. M. Wilson Title: Professor of Civil and Environmental Engineering ACKNOWLEDGEMENTS My deeply sincere gratitude goes to a large number of people who give me guidance and assistance, inspiration and patience. First I would like to thank my advisor, Nigel Wilson, who give me the guidance, motivation and encouragement throughout the 2 years of my stay in MIT. He erects a statue of erudite literate in my heart. I have come to respect and admire Nigel for the high standards he has both for himself and for his students, his scrupulous attitude as a researcher, his humorous intelligence as a lecturer and his dedication both to education and to the filed of urban transit. My stay at MIT worked out better than I could have ever expected, and I owe much of it to Nigel. I hope one day I could be more like Nigel. I would also like to thank Anne Herzenberg, Jeffrey A. Parker and Frank Feltes of MBTA who provide us both great suggestions for the project and important information that I need to complete it. In addition, they help me collect data from the OCS database and at Braintree Branch. Without their help and insights, my research will never be done. Su Shen and Susan O'Dell help me get past many project problems. Susan's thesis develop the basis of my research, and Su bring out excellent contributions to the travel time estimation on the Braintree Branch. Finally, I would like to thank my wife, Jiangmai, who support and encourage me through 12 years, who never loses confidence to our future, who always with me through every happiness and bitterness. This thesis is dedicated to my parents. I hope they are proud of me forever. Table of Contents A BSTRA CT .................................................................................................................................................. 2 ACKNOWLEDGEMENTS .................................................................................................................. 3 TABLE OF CONTENTS ....................................................................................................................... 4 LIST OF FIGURES ................................................................................................................................ 6 LIST OF TABLES ................................................................................................................................ 8 CHAPTER 1 INTRODUCTION .......................................................................................................... 9 1.1 RAIL TRANSIT SERVICE ................................................................... 10 1.2 THE MBTA APPLICATION CONTEXT..................................................................... 12 1.3 PRIOR RESEARCH .............................................................. 15 1.3.1 Bunching ............................................................. 15 1.3.2 H olding ............................................. ....................... 17 1.3.3 Expressing and Short Turning ............................................................. 20 1.3.4 Others ...................................................... ............. ............. 22 1.4 THESIS ORGANIZATION ............................................................... 23 CHAPTER 2 DISRUPTION CONTROL SYSTEM ............................................ ................ 24 2.1 TYPES AND FREQUENCIES OF DISRUPTIONS................................................................................ 24 2.2 MAJOR DISRUPTION .......................................................................... 26 2.2.1 Objective and Methodology ........................................ ................... 26 2.2.2 Alternative States and Strategies ........................................ ................. 27 2.2.3 R ed L ine A nalysis.................................................................................................................... 32 2.3 M INOR DISRUPTION ................................................................ 43 2.3.1 Objective and Methodology ........................................ ................... 44 2.3.2 Systems Description ..................................................... 46 2.3.3 Control Strategies............................................ ........................ 46 2.3.4 Conclusion .......................................................... 51 CHAPTER 3 DISPATCHING CONTROL PROBLEM................................. 53 3.1 DISPATCHING PROBLEM .................................................................... 53 3.2 MATHEMATICAL ANALYSIS .............................................................................. 55 3.2.1 Notation .............................................................. 55 3.2.2 Headway ............................................................... 57 3.2.3 Optimal Headway ......................................................... .......... ............. 58 3.3 CONTROL STRATEGIES FOR MBTA BRAINTREE BRANCH DISPATCHING PROBLEM ...................... 62 CHAPTER 4 DWELL TIME FUNCTION ......................................................................................... 67 4 .1 T HEORY ....................................................................................................................................... 68 4.2 DATA COLLECTION AND ESTIMATION ...................................... ........................... 72 4.2.1 Data Available ......................................................................... 72 4.2.2 Data Needed .................................................... ............................. 73 4.3 M ODEL ESTIM ATION ................................................................................................ .................. 82 4.3.1 M odel I .......................................................... .................................................. 82 4.3.2 Model 2 ........................................ ................................................. 83 4.4 C ONCLUSION ........................................................ ............. .. ......................................... 84 CHAPTER 5 HEURISTIC REAL-TIME DISPATCHING CONTROL MODEL ............................. 86 5.1 DISPATCHING STRUCTURE AND STRATEGY ................................................................. 86 5.1.1 Definition of the DispatchingProblem