PROCEDURES FOR PLANNING MULTI-LEG JOURNEYS WITH FIXED-ROUTE AND DEMAND-RESPONSIVE PASSENGER TRANSPORT SERVICES

Public transportation information systems that provide journey planning services to travelers have recently been introduced. This paper describes journey planning procedures designed for use in a traveler information system covering fixed-schedule and demand-responsive public transportation modes. The goal is to construct a sequence of journey legs to meet a traveler\u27s requirements with the least possible generalized cost, subject to time windows and other constraints. A journey may be carried out in a single leg by walking or by taking a taxi all the way from the origin to the destination, or by a sequence of one or more legs carried by public transportation services sandwiched between walked segments connecting an initial pickup and final setdown stop. The public transportation services may include fixed-route modes such as bus and train, and demand-responsive services running between fixed points. The main planning procedures are a high-level request broker and a branch and bound procedure to handle multi-legged journeys; the request-broker also invokes a fleet-scheduling module to obtain bookings on demand-responsive services. The paper describes planning conditions, the planning procedures and reduction techniques that are used to obtain acceptable computational performance. Tests with simulated demand suggest that the procedures are well suited for use in a real-time traveler information system. The planning procedures described here are unique in their coverage of both static and dynamic public transportation services, and in their handling of interdependencies between temporal conditions and a planning criterion of generalized cost