高速公路限速策略优化方法与评价模型

为解决限制速度值确定不合理、限速方式不适用以及限速区间长度设置不恰当等问题, 对驾驶人行驶体验以及限速管理可信度的负面影响, 优化了高速公路限速区间最小长度、限制速度值、限速区间划分的确定方法, 进而提出了以安全车速与通行效率为依据的高速公路限速区间优化与评价模型。依据驾驶人视认距离、限速标志设置前置距离和驾驶人心理稳定距离, 标定计算模型中的限速区间最小长度。以行驶速度是否易发生突变为标准, 采用不定长法将不同路段划分为6种组合类型, 建立基于不同组合路段的限速预测模型。采用有序聚类分析法中基于划分和层次的分析方法, 以满足限速区间最小长度和交通延误最小2个方面为目标进行优化限速区间的划分。同时, 选取交通冲突率作为表征交通安全的指标, 选取交通延误时间作为表征交通效率的指标, 建立评价指标模型; 最后通过对比分析优化前后的指标来验证限速区间优化方法的有效性。以某山区高速公路为对象应用VISSIM开展限速优化仿真实验, 结果表明: 优化后安全评价模型参数值比原方案降低了约29.49%, 效率评价模型参数值比原方案提高了约21.90%, 优化后的高速公路整体安全性以及通行效率均得到提高。所提出的高速公路限速区间确定方法以速度突变为基准, 结合路段的属性及指标特点, 能够优化限速区间长度的制定和区间的划分。 

An Optimization Method and Evaluation Model for Designing Speed Control Zones of Freeway

The problems such as unreasonable determination of the speed limit, invalid rate-limiting way, and improper setting of speed limit range can impact the road safety. These problems can impact driving experience and the credibility of speed limit management. A model is developed based on safe speed and traffic efficiency. Then, the minimum length of speed limit zone, the limit of vehicle speed, and the division of speed limit zone are optimized. On this basis, an evaluation model of speed limit zone of freeway is optimized. The minimum length of the speed limit zone is calibrated according to the driver's vision recognition distance, the pre-setting distance of speed limit sign, and the driver's psychological stability distance. These limitations include the drivers' visual distance, the pre-setting distance of speed limit sign, and the drivers' psychologically stable distance. Then, according to whether the speed is prone to sudden change, a road segment is divided into six different types of combination by the method of variable length. On this basis, the speed limit prediction models of different combination roads are determined. The method based on partition and hierarchy in cluster analysis is used to optimize the partition of speed limit zone from two aspects. The minimum length of speed limit zone and the minimum traffic delay are optimized.At the same time, the traffic conflict rate is chosen as the index of traffic safety. And the traffic delay time is chosen as the index of traffic efficiency. The evaluation index model is established. Then, the validity of the method is verified by the comparison and analysis of the indexes before and after optimization. The simulation experiment of speed limit optimization is carried out on a mountain freeway with VISSIM. The results show that the parameters of the optimized safety evaluation model is reduced by about 29.49%. The parameters of the efficiency evaluation model is increased by about 21.90%. Moreover, the safety and overall traffic efficiency of the optimized freeway are improved. The speed limit zone determination method in this paper is based on the sudden change of the vehicle speed.This method combines the attribute and index characteristics of freeway sections. The proposed optimization method can significantly optimize the length of speed limit zone and the division of the zone.