城市道路信号控制交叉口左转车流是造成交叉口冲突和拥挤,以至于形成交通瓶颈的主要原因之一。通过分析实施U-turn的交通效益和影响因素,利用稳态模型、过渡函数和可插间隙理论建立了基于交叉口车均延误和U-turn行程时间的延误模型。最后利用实例,得到U-turn设计可使饱和度最高下降29%,车均延误最高下降63%,从而使交叉口服务水平有较大提高。 Urban Road Signal Control Intersection Left turn traffic flow is one of the main causes of traffic bottlenecks caused by traffic congestion and congestion at intersections. By analyzing the benefits and influencing factors of U-turn traffic, a delay model based on vehicle-average delay and U-turn travel time is established by using steady-state model, transition function and pluggable gap theory. Finally, by using the example, the U-turn design can reduce the maximum saturation by 29% and the maximum vehicle delay by 63%, which can greatly improve the service level of the intersection.