Joint optimization of fixed route bus networks and complementary paratransit service areas

An optimization-based approach is proposed for the joint design of fixed-route bus networks and the service areas of complementary paratransit services. Complementary paratransit systems provide transportation to people with disabilities within a service area (PSA) that is traditionally designed as a function of the spatial layout of a fixed-route bus network. The proposed problem accounts for effectiveness and equity objectives for the bus and paratransit services. A constraint on the minimum extension PSAs is considered, which is of practical interest given the coverage regulations faced by transit agencies in some jurisdictions. A two-step procedure is proposed to find solutions to the design problem. In the first step, bus route network designs are generated, along with their minimum PSAs. In the second step, a genetic algorithm improves upon the PSAs generated in the first step. Simulation tests were performed to illustrate the application of the proposed methodology.