Feeder Bus Network Design Problem: a New Metaheuristic Procedure and Real Size Applications

The present paper deals with the transit network design problem related to the feeder routes defined as transit services for the connection of local areas, where the demand has to be gathered, with the stops of the main transit network, usually railway or underground station. The objective of the research is the development of a procedure that simultaneously generates routes and frequencies of the feeder bus network in a real size large urban area. The solving procedure is articulated in 2 phases: in the first one, a heuristic algorithm generates two different and complementary sets of feasible routes, in order to provide a good balance between maximization of the service coverage area and minimization of the overall travel time. First set is composed by circular routes, generated solving a travelling salesman problem (TSP) connecting the highest demand node pairs in the area with the stop of main transit network. The second feasible set aims at developing feeder routes more direct than the others using the k-shortest path algorithm. The set of all feasible routes, generated taking into account only the main skeleton of the road network, is then the input data for the second phase where a GA is utilized for finding a sub-optimal set of routes with the associated frequencies. The proposed procedure has been implemented on two real-life size networks, Winnipeg and Rome, in order to compare its effectiveness with the performances of the existing transit networks. The results of the applications of the design procedure show that the feeder routes imply a more integrated transit network with a reduction of the total travel time, despite an increase of the number of transfers, in a more efficient way as demonstrated by the reduction of the operating costs and the increase of the average load factor.