Abstract: The conventional traffic organization and signal control are not ideal for handling asymmetric traffic flow, which can cause waste of travel time and road resources. In view of the characteristics of asymmetric traffic flow, the signal control optimization scheme of asymmetric traffic flow intersection with shifted left-turn lane is proposed. With the objective of minimizing the delay of both straight and left-turn vehicles, a model for optimizing the spatial and temporal resources of the shifted left-turn intersection and a model for calculating the vehicle delay are established. Experiments were designed to study the effect of traffic flow asymmetry and the length of the shifted turn lane on the delay of left-turning vehicles, to analyze the adaptation of asymmetric traffic flow to the shifted left-turn lane, and to simulate the optimization scheme using VISSIM software. The simulation results show that: compared with the status quo of the intersection, the average delay of vehicles in Scheme 2 is reduced by 27.2% and the average queue length is reduced by 29.7%, which indicates that the signal control scheme of shifted left-turn lane can greatly improve the driving conditions of vehicles at the intersection of asymmetric traffic flow, reduce the average delay time of vehicles and make the traffic flow run more smoothly.

Key words: traffic engineering; shift left-turn signal control; asymmetric traffic flow; delay model

摘要： 常规的交通组织与信号控制处理不对称车流的效果不理想，会造成时间、道路资源的浪费。针对不对称交通流的特性，提出设置移位左转车道的不对称交通流交叉口信号控制优化方案。以直行车辆与左转车辆车均延误最小为目标，建立移位左转交叉口时空资源优化模型与车辆延误计算模型。通过研究交通流不对称程度与移位左转车道长度对左转车辆延误的影响，分析不对称交通流移位左转车道的适应性，并运用VISSIM软件对优化方案进行仿真。仿真结果表明：与交叉口现状相比，方案2中车辆的平均延误降低27.2%，平均排队长度降低29.7%，说明移位左转车道信号控制方案能极大改善不对称交通流交叉口车辆的行驶情况，减少车均延误时间，使车流运行更加顺畅。

关键词: 交通工程；移位左转信号控制；不对称交通流；延误模型