Optimal Modification of Urban Bus Network Routes Using a Genetic Algorithm

Abstract

The bus network design problem refers to a determination of optimizing the network of bus routes, usually in urban areas. The optimal routes must comply with a given passenger demand matrix and attain a compromise best solution from the user, the operator, and the community. This paper proposes the use of a genetic algorithm as a tool to handle the complexity of the bus network design problem. The methodology developed considers a mechanism to maintain as many satisfactory routes of the existing network as possible and, at the same time, to incorporate experience-based suggestions, such as minimizing of the number of transfers required by a passenger, into the revised bus network. The solution method, using genetic algorithm, has four steps: (1) generating a set of potential routes, (2) designing the bus network, (3) checking the routes for implementation, and (4) examining the extension of routes for improvement. The proposed method is validated through a benchmark bus network and a case study. The result of the case study, with a bus network serving a city with a population of 3.2 million, shows an improvement of 26.36% in the objective function value over the existing bus network. This improvement was realized by modifying only 36% of the routes while the remaining 74% of the existing network remained intact.