Optimising the design of a limited-stop bus service for a branching network

This paper presents an optimisation model for designing limited-stop lines for a branching bus network composed of several feeder lines and a trunk line. On the basis of the different demand patterns in the feeder lines and the trunk line, passenger assignment in the bus route is considered. The optimisation model is used to calculate the total cost of a transit system in which limited-stop services are implemented on bus routes. The total cost includes the cost of passenger waiting time and in-vehicle time, as well as the operator cost for each bus route. With better service planning of limited-stop lines, based on the demand behaviour in high-demand corridors, the total cost can be reduced (compared with the normal service costs of stopping all buses at all stops). A genetic algorithm is adopted to ascertain the optimal model. This algorithm can determine continuous and discrete optimisation variables: the optimal bus frequencies and the best pattern of limited-stop use for each bus route. Finally, a numerical example is optimised. The results show that a limited-stop service for branching corridors can reduce the total cost of the transit system.