Optimizing reliable timetable for bus transit network: model formulation and solution

Timetabling for bus transit network is one of knotty optimization problems in public transit planning process for transit agencies, because it must consider the synchronization of vehicle timetables when determining the departure time of each trip so that transfers within the network are well timed. Furthermore, the reliability of timetable that transit operators always struggle to ensure is also an important factor, which can enhance the probability of coordination of vehicles at transfer stations in the coming actual operations. In this paper we first propose a reliable timetable design problem for transit network by taking into account the stochastic bus travel times. A novel optimization model is developed to decide the departure time of each trip and the slack time associated with each transfer station to make a trade-off between operational cost and waiting time cost for transfer. Considering the feature of the optimization model, this paper subsequently proposes a simulation procedure based on simulated annealing algorithm. Finally, the proposed model is verified by the solution method under a hypothetical transit network and the computational results are reported.