基于交通冲突的山区高速公路可变限速控制方法
Variable speed limit method of mountainous expressway based on traffic conflict Index

为了提高山区高速公路交通运行的安全性，将相邻路段速度差以及交通冲突风险最小化。针对以往研究缺乏从交通流稳定性层面对可变限速（VSL）系统控制效果分析的现状，提出基于METANET宏观动态交通流模型的可变限速控制方法，建立山区高速公路多目标限速优化控制模型并开发仿真环境进行测试，分析可变限速控制系统对山区高速公路交通运行安全性的影响。首先，构建基于METANET宏观动态交通流模型的可变限速控制策略。通过METANET宏观动态交通流模型实现对交通流在时空域中运行态势的描述，以相邻路段速度差以及路段冲突风险，即替代型交通安全指标最小为优化目标，以交通系统运行效率以及限速值变化范围为约束条件，构建了可变限速多目标优化控制模型，采用基于群智能的差分进化算法求解计算可变限速值。应用VB与MATLAB混合编程技术，开发基于VISSIM COM的仿真平台测试控制效果。最后，以实测山区高速公路交通流数据对仿真模型进行校准，并综合考虑山区高速公路交通特性、驾驶人服从率等因素，运用VISSIM COM/MATLAB模拟环境对山区高速公路进行可变限速控制。研究结果表明：与未实施可变限速时相比，对山区高速公路实施可变限速控制，能够显著降低速度离散性，使可变限速路段各分段中心断面的速度标准差降低30%~40%，山区高速公路交通安全性得到了提高。
In view of the lack of research on the control effect of the VSL system in a traffic flow stability layer, METANET macro traffic flow model was proposed，with the purpose of improving traffic safety on mountainous highways by minimizing the risk of traffic conflicts and decreasing the speed difference in adjacent road sections. The variable speed limit method was used to establish a multi？？target speed limit optimization model for mountainous highways and develop a simulation environment for testing different conditions. The impact of the variable speed limit control system on the safety of mountain highway traffic was analyzed. First, a variable rate control strategy was constructed based on the METANET macro traffic flow model, which was then employed to describe traffic flow in the space？？time domain. The ultimate aim was to minimize adjacent section speed differences and thus the total conflict risk. Setting operation efficiency and speed limit range as constraints, the multi？？objective optimization variable speed limit model was constructed, and VSL ratios were calculated using the differential evolution algorithm based on swarm intelligence. VB and MATLAB hybrid programming technology was applied, and the speed limit control effect was tested by developing a simulation platform based on traffic flow simulator VISSIM COM. Finally, the simulation model was calibrated with actual mountainous highway traffic flow data, with comprehensive consideration given to factors such as mountain highway traffic characteristics and driver compliance rates. The VISSIM COM/MATLAB simulation environment was used to implement the variable speed limit on the mountain expressway. The results show that speed limit control significantly reduces speed dispersion, resulting in a 30% to 40% reduction of velocity standard deviation， comparison with the case where variable speed limit control is not implemented. This indicates that variable speed limit control can enhance traffic safety in mountainous