Optimal zone sizes and headways for flexible-route bus services

Abstract

Flexible-route bus systems serving passengers at their doorsteps may be preferable to fixed-route bus systems in areas with low demand densities or whose roads cannot accommodate relatively large fixed-route buses. Flexible-route systems may also be preferable for elderly or handicapped riders for whom accessing the pre-determined stops on fixed routes is difficult. Since bus systems with flexible demand-responsive routes retain the economic and environmental advantages of public transportation, it is important to analyze them and optimize their characteristics to match their operating environments. This study shows how the total cost can be minimized for a flexible-route bus system with a many-to-one demand pattern by jointly optimizing its headway and service zone size. Numerical results demonstrate the model's applicability and indicate how such flexible-route systems should be adapted to demand characteristics and planning constraints.