Study of dynamic headway control bus dispatching rules.

Abstract

The critical criterion for evaluating a bus control strategy is how well it can improve the reliability of bus service. For high-frequency urban bus service, the service reliability is more a function of bus regularity than schedule adherence. Previous research has shown that headway control strategy is more appropriate for improving bus service with high service frequencies than the traditional schedule control strategy. A customer survey has been undertaken to determine what is the largest headway, i.e., the time between the departure of two successive buses at stops of a given route, such that headway control strategy is still reasonable for bus control. Based on the results of our survey, the research of this thesis is focused on headway control when it is believed to be suitable. Regularity of a given route for a given period of the day can be controlled through real-time actions aimed at maintaining adherence to the planned headway. While holding policies have been shown to be very effective in keeping the headway constant, they usually suffer from an inability to adjust quickly to the changing conditions along the route, such as buses breaking down, or not pulling out from the garage. In this thesis, we propose an improved holding policy--"flexible scheduling" as a means for the buses along the route to auto-regulate themselves based on real-time data obtained through the Automatic Vehicle Location Control (AVLC) system, a technology that allows the controller to know the relative position of buses along the route. The idea of flexible scheduling will be discussed in detail. Experimentation of this policy will be conducted on a simulation model. Results will be reported and analysed. A user interface which provides easy access to both the simulation model and a control module is also developed to provide a better working environment to the users of these models. Finally, conclusions and avenues for future research will be discussed.