Expressway traffic flow under the combined bottleneck of accident and on-ramp in framework of Kerner’s three-phase traffic theory

Abstract

Many traffic accidents occur in the merging and diverging area of expressway and ramp, which forms the combination bottleneck of traffic accidents and ramp at the same time, and has a negative impact on traffic flow. Based on the classic KKW (Kerner–Klenov–Wolf) model of three-phase traffic flow theory, this paper introduces traffic accident and defines the priority rule of vehicle lane changing in front of the accident site, proposes the traffic flow model of expressway ramp system under the accident conditions, and simulates and analyzes the impact of traffic accident on the traffic flow under the open boundary condition. It is found that the congestion caused by the accident will not propagates to the upstream basically under the free flow, but will obviously propagate to the upstream under the synchronized flow. Besides, the combined bottleneck effect of accidents and on-ramp can be clearly found under synchronized flow. This work is helpful to understand the mechanism of traffic congestion and provide reference suggestions for traffic control under accident conditions.