Simulation of Road Capacity Considering the Influence of Buses

The traditional cellular automata model cannot fully demonstrate the effect of buses on road capacity due to the incapable of considering the difference in dynamic performance and driving behaviors between buses and other vehicles. In this paper, a novel cellular automata model accounting for car-following and lane-changing behaviors was developed to investigate the relationship between the multilane road capacity and the proportion of buses. The parameters of the model were calibrated and verified using the data collected from a real-word road with heterogeneous traffic flow. The calibration result indicates that the proposed model can accurately describe the evolution of traffic dynamics on multilane roads. It is found that drivers have a specific preference in determining the target lane in the lane-changing process. Under the same conditions, bus drivers prefer to choose the side lane of the road, while drivers of other vehicles prefer to select the middle lanes. Besides, the preference for the target lanes affects the lane-changing behaviors of the drivers, resulting in a considerable difference in optimal traffic density and maximum traffic volume in different lanes. Moreover, the simulation result suggests that the proportion of buses has a significant impact on road capacity (e.g., the capacity is reduced by as much as 18%). To increase road capacity and improve bus services, based on the proposed model, transit authorities can dynamically allocate the limited road space to buses and other vehicles according to the proportion of buses.