Integrating line planning, timetabling, and vehicle scheduling: a customer-oriented heuristic

Given an existing public transportation network, the classic planning process in public transportation is as follows: In a first step, the lines are designed; in a second step a timetable is calculated and finally the vehicle and crew schedules are planned. The drawback of this sequence is that the main factors for the costs (i.e. the number of vehicles and drivers needed) are only determined in a late stage of the planning process. We hence suggest to reorder the classic sequence of the planning steps: In our new approach we first design the vehicle routes, then split them to lines and finally calculate a (periodic) timetable. The advantage is that costs can be controlled during the whole process while the objective in all three steps is customer-oriented. In the paper we formulate an integrated model from which we develop this new approach, discuss the complexity of the resulting problems, and present a heuristic which we applied within a case study, optimizing the local bus system in Göttingen, Germany.