Resolution of Station Level Constraints in Train Unit Scheduling

Train unit scheduling assigns vehicles to cover all trips of a fixed timetable satisfying seat demands at minimum operational costs. Solved as a network flow problem, train stations are simplified to single points where certain station operation details are not considered. For instance, when a trip is covered by coupled train units, the coupling order is left undetermined, and infeasibility may arise because of track and platform layouts, movement directions and timings. This paper investigates the resolution of such station level constraints for a multi-commodity flow based approach; in particular, we shall focus on feasible coupling order as an example. A hybrid-iterative approach is proposed for coupling order assignment with re nement of train unit scheduling by considering conflict-free linkage implementation at the station level.