Flexible timetables for real-time train rescheduling

A common strategy for railway traffic management consists in the off-line development of a detailed timetable, and operating in real time with strict adherence to it. In real time, unforeseen events may require to partially modify the planned timetable. A recent trend in railway companies is for managing congested areas by planning less in the off-line phase, and solving train conflicts in real time. In this paper we investigate the concept of flexible timetable, and the relations between flexibility and delay minimization. We use a detailed model for conflict resolution, based on the alternative graph formulation, and a branch and bound algorithm for solving the problem at optimality. We compare optimal solutions computed when varying timetable flexibility. An extensive computational study on a small and complicated rail network has been carried out, based on a bottleneck area of the Dutch railway network.