Optimizing Timetable Synchronization for Rail Mass Transit

• Published in: Transportation science Vol. 42; no. 1; pp. 57 - 69
• Main Authors: Wong, Rachel C. W, Yuen, Tony W. Y, Fung, Kwok Wah, Leung, Janny M. Y
• Format: Journal Article
• Language: English
• Published: Linthicum, MD INFORMS 01.02.2008; Transportation Science & Logistic Society of the Institute for Operations Research and Management Sciences; Institute for Operations Research and the Management Sciences
• Subjects: Analysis; Applied sciences; Exact sciences and technology; Genetic algorithms; Ground, air and sea transportation, marine construction; Headway; Heuristic; Hong Kong; Integer programming; Linear algebra; Linear programming; Literature reviews; Management; Mass transit; Optimal solutions; Optimization; Optimization algorithms; Passengers; Programming; Public transportation; rail; Rail transit; Railroad trains; Railroad transportation; Railroads; Railway networks; Railway transport; Railway transportation and traffic; Run time; Scheduling; Strategic planning; Studies; Time; timetabling; Trains; Transfers; Transportation; Transportation planning, management and economics; Transportation schedules; Transportation services; Transportation waiting times; Travelers; Urban areas; Vehicles; Hong Kong; Asia; China; Hong Kong, China; Hong Kong China; rail; Scheduling; Synchronization; Modeling; Optimization; Public transportation; Case study; timetabling; Urban transportation; mass transit; transfers; Timetabling problem; Rail transportation; Heuristic approach; Planning; Performance
• ISSN: 0041-1655; 1526-5447
• DOI: 10.1287/trsc.1070.0200

In most urban public transit rail systems, passengers may need to make several interchanges between different lines to reach their destination. The design of coordinated timetables that enable smooth interchanges with minimal delay for all passengers is a very difficult task. This paper presents a mixed-integer-programming optimization model for this schedule synchronization problem for nonperiodic timetables that minimizes the interchange waiting times of all passengers. A novelty in our formulation is the use of binary variables that enable the correct representation of the waiting times to the "next available" train at the interchange stations. By adjusting trains' run times and station dwell times during their trips and their dispatch times, turnaround times at the terminals, and headways at the stations, our model can construct high-quality timetables that minimize transfer waiting times. We also discuss an optimization-based heuristic for the model. We have tested our algorithm for the Mass Transit Railway (MTR) system in Hong Kong, which runs six railway lines with many cross-platform interchange stations. Preliminary numerical results indicate that our approach improves the synchronization significantly compared with the current practice of using fixed headways and trip times. We also explore the trade-offs among different operational parameters and flexibility and their impact on overall passenger waiting times.