A transit network design model for urban areas

Transit network design is discussed in an extensive amount of literature, with several optimization procedures to solve the design problem by determining transit routes and associated frequencies. In recent years, following the evolution of operational research and the increasing power of computational machines, studies have had a new impulse. The design model must become an important tool to develop an intensive, and not extensive, transit network of a new generation characterized by efficiency, integration between routes, and structured to improve service quality and riderships. The purpose of this paper is to develop a new heuristic bus design model for urban areas, formulated as an optimization problem (minimization of the overall system costs). The basic framework of the model is established on three phases: 1) a heuristic algorithm to generate a set of feasible routes; 2) a genetic algorithm to find the optimal sub-set of routes; 3) final improvement of the network configuration. The model output is the bus routes, the frequencies and the vehicle sizes. This paper presents a synthetic state-of-the-art proposal about the bus network design problem, describes the developed model and presents some final considerations about the solution approach proposed, and possible further developments.