Developing a dynamic utilisation scheme for exclusive bus lanes on urban expressways: An enhanced CTM-based approach versus a microsimulation-based approach

Abstract

In the current practice of bus rapid transit (BRT) system, under-utilized exclusive bus lanes (EBL) could negatively impact the system efficiency, particularly when traffic congestion occurs on regular vehicle lanes during peak period. In this paper, we propose an EBL sharing scheme to dynamically control the usage of the EBL by regular vehicles based on connected vehicle technologies without disturbing normal operation of the BRT system. An enhanced cell transmission model (CTM)-based approach and a simulation-based approach are proposed to model the traffic dynamics of a BRT section currently running in Chengdu, China. The optimal entry/exit proportion of regular vehicles are derived by minimizing total car delay on both the EBL and regular lanes given fixed bus service. The performance of the proposed dynamic sharing control scheme is evaluated under-saturated and over-saturated conditions. The sensitivity of the BRT service frequency and the average bus waiting time on the performance of the control scheme is also analysed. The results show that when traffic becomes over-saturated, delays on regular lanes can be significantly reduced by allowing optimized proportion of regular vehicles to use the EBL. However, it is unnecessary to use the EBL where traffic demand on regular lanes is low.