Scheduling and resource optimization in rail operations : models and algorithms

Abstract

In this thesis, we address important optimization issues in railway operations planning, namely train scheduling and resource optimization. Railway resources such as tracks, overhead equipment, locomotives, passenger and freight cars require huge capital investments and long lead time for procurement and installation. Large railway systems such as those in US, China, Europe and India need investment of billions of dollars on an on-going basis. Typically, installation of new tracks needs investment of USD 2 million per kilometre for normal tracks and more than USD 10 million for high speed tracks. Countries such as China and India have the railway network span over 120,000 and 64,000 track kilometres respectively, and are rapidly expanding their rail network. Indian Railways have more than 10,000 locomotives in inventory, and this represents an investment of about the USD 30 billion. Given these large investments and growth in traffic, even marginal improvements in resource utilization can result in significant cost savings. The specific problems identified and studied in this thesis are in the context of Indian Railways where the author has been working for more than 17 years. However, the problems studied and contributions made are fundamental and can be applied across all railway systems. We present these selected problems as three independent essays in this thesis. The first essay entitled Integrated Train Timetabling and Platforming Problem comprehensively addresses the problem of train scheduling in heterogeneous, high density double track corridors on Indian Railways (IR). As these corridors are intensively utilized, efficient scheduling of trains with different priorities, speeds and halt pattern is critical for optimization of track capacity. The key challenge for train planners is the planning of overtaking of trains having different priorities such as non-stop, suburban, express, commuter, container and heavy haul freight trains. While freight trains generate significantly higher revenue as compared to passenger trains, non-stop and express trains are given higher priority in IR due to the political sensitivity of delay in passenger services. Therefore, planning for overtaking of multiple trains without negative impact on throughput time is crucial for efficient scheduling of freight trains on these corridors dominated by passenger trains. The existing approaches divide train scheduling into two distinct problems the Train Timetabling Problem (TTP) and the Train Platforming Problem (TPP) and solve them sequentially. In this essay, we develop a novel Integer Programming (IP) model that integrates the TTP and TPP into a single problem called the Integrated Train Timetabling and Platforming Problem (ITTPP). Our model explicitly handles station capacity constraints, assigns trains to platforms in a conflict free-manner with a possibility of overtaking of multiple trains at a station, and directly generates feasible timetable for the entire corridor that can be implemented without any further adjustments. We…