公路平交路口左转专用道设置阈值的仿真研究

摘要

公路平面交叉口左转专用道的恰当设置在提高交叉口安全性的同时,也是改善交叉口运行状况的一种有效手段,确定左转专用道的设置阈值成为一个重要问题.以二级公路典型无信号交叉口的行程时间、延误、服务水平及冲突次数为目标,运用交通仿真分析技术对交叉口设置左转专用道和直左混行车道进行对比仿真分析.结果表明,左转专用道的设置与进口道的交通量相关.其中设置左转弯车道与否的行程时间、延误、冲突都随进口道交通量的增加而增加,当进口道交通量大于600 veh/h时,设置了左转专用道的通行能力及安全性较优,当交通量大于1 000 veh/h时,设置左转专用车道的延误和冲突次数急剧增加,服务水平和平均速度降低,表明左转专用道的设置阈值为600～1 000 veh/h.%The appropriate set of left-turn lane of highway intersections can improve the safety and operation efficiency.It is an important issue to determine the threshold value of the left-turn lane in these intersections.The study had taken the travel time, delay, levels of service and conflict times as the objectives, and had a contrast simulation analysis to left-turn lane and mixed lane by traffic simulation technology.The study shows that the setting of left-turn lane is correlation to the traffic volume of access.The travel time, delay and conflicts increase with the increasing of traffic flow.When the traffic volume exceeds 600 veh/h, the capacity and safety of the intersection become better after the setting of left-turn lane, while the traffic volume exceeds 1 000 veh/h, the delay and conflicts increase rapidly with the levels of service and average speed reduced.The results shows the threshold value of left-turn lane is 600～1 000 veh/h.This paper also provides a quantitative method for the setting of the left-turn lane in the intersections of secondary highways.