城市干路交叉口路侧交通标志遮挡失效研究

A Study of Occlusion Failure of Traffic Signs on Roadside at Intersections of Urban Arterial Roads

为了分析外侧车道中大型车对城市干路交叉口路侧交通标志遮挡的影响,基于空间遮挡模型存在缺陷,研究了交叉口路侧交通标志时间遮挡模型。通过驾驶人最大视域角及小型车、大型车在路段上运行时与交通标志存在的几何关系,确定了遮挡模型的开始计数条件、停止计数条件及遮挡判定条件。以驾驶人视认交通标志需要的最小时间为依据,建立驾驶人错过交通标志的概率模型。利用Vissim仿真获取仿真时间、车辆编号、路径编号以及小型车、大型车车头坐标等数据,依据遮挡模型的3个条件进行小型车驾驶人错过交通标志的概率计算。从外侧车道中大型车比例和行驶速度2个方面分析其对交通标志遮挡的影响。结果表明,原始数据下得到小型车驾驶人错过交通标志的概率为0.042 6。在交叉口进口道交通量、绿信比等参数不变的条件下,将外侧车道中大型车比例由0.10增加至0.40时,小型车驾驶人错过交通标志的概率由0.021 3增加至0.117 6,二者呈正相关;外侧车道大型车行驶速度增大,驾驶人错过交通标志的概率并非一定降低,还取决于外侧车道中大型车的数量。

In order to analyze influences of large-scale vehicles on roadside occlusion at intersections of urban arterial roads, a time-blocking model is developed based on a spatial occlusion model. Conditions of start count, stop count, and occlusion determination are determined by the maximum field of view angle of drivers and geometric relationships between small and large-scale vehicles and traffic signs, while they are running on road sections. Based on the minimum time required for drivers to visually identify traffic signs, a model is established to calculate probability that drivers of small vehicles missed traffic signs. A Vissim simulation is used to obtain simulation time, vehicle number, path number, and head coordinates of small and large vehicles. According to three conditions of the occlusion model, the probability is calculated. Influences of ratio and driving speed of large-scale vehicles on the occlusion of traffic signs are analyzed. The results show that the probability of the original data is 0.042 6. Under the conditions that the traffic volume of entrance roads at intersections and green signal ratio both remain unchanged, the probability increases from 0.021 3 to 0.117 6 when the proportion of large-scale vehicles in the outer lane increases from 0.10 to 0.40, which is positively correlated. When large-scale vehicles in the outer lane increase speed, the probability does not necessarily decrease. It also depends on the number of large-scale vehicles in the outer lane.