高速公路可变限速控制策略安全性效果仿真

为了减少高速公路常发交通瓶颈上游路段运动波传播引发的追尾事故,在分析PARAMICS微观仿真模型的基础上,建立了可变限速控制仿真平台,在高速公路入口匝道交通瓶颈仿真路段,采用事故预测模型定量研究路段内冲击波传播过程中追尾事故的实时风险,提出了减少事故发生概率可变限速控制策略.结果表明:减少事故风险效果最好的控制策略是将阈值设置为预测事故概率等于0.25,限速值变化周期为120 s,限速值降低幅度为20 km/h,恢复幅度为10 km/h,相邻路段限速值差为20 km/h.采用可变限速最优控制策略后,高速公路瓶颈上游路段追尾事故风险降低了20%. 

Simulating Impacts of Variable Speed Limits on Traffic Safety on Freeways

To reduce the occurrence of rear-end collisions during the propagation of kinematic waves in freeway section upstream of a recurrent bottleneck, a simulation platform for variable speed limits (VSLs) was developed using the PARAMICS microscopic simulation model. The simulation network is a freeway section containing an on-ramp bottleneck. A crash prediction model was adopted to quantify the real-time rear-end collision risks accompanying the propagation of kinematic waves in the section upstream of the on-ramp bottleneck. Control strategies for VSLs were proposed to reduce the collision potential. Results show that the optimal strategy to reduce collision risk is that the startup threshold of collision probability is set to 0.25, time step for VSL change to 120 s, speed step for reduction to 20 km/h, speed step for recovery to 10 km/h, and difference between adjacent speed limit signs to 20 km/h. Using the optimal control strategy for VSLs, the rear-end collision risk in the freeway section upstream of the recurrent bottleneck is reduced by 20%.