The impact of bus fleet size on performance of self-equalise bus headway control method

Headway fluctuation and bus bunching are common in transit operations, while holding control is a proven strategy for the reduction of bus bunching. Recently, benefited from the advances in technology and tools, adaptive control method for equalising bus headways on the bus route gradually has become successful. Although this method performs well in regulating the bus operation, it does not consider the impact of the number of buses on the bus route. The control method may fail to regulate bus headways due to an insufficient number of buses, despite the control method itself being effective. Therefore, this paper explores the relationship between the number of buses on the bus route and the performance of the self-equalise bus headway control method. A model is proposed to search the suitable number of buses on the bus route by analysing the changes of the bus headway standard deviations with increasing the number of buses. Furthermore, a set of numerical tests were conducted. According to the results of the analysis, under high demand, the performance of the self-equalise bus headway control method is more sensitive to changes of bus number on the bus route.