Critical Condition for Setting Left-turn Waiting Area

To seek the theoretical foundation for the layout of the left-turn waiting area, the geometry of the intersection was analyzed,and the geometrical critical condition for set up left-turn waiting area was put forward.The model of left-turn queuing location was established based on accumulation curve and traffic wave theory.On the condition that channelization and signal timing method of intersection is invariable,the critical volume and limit volume under the restriction of queue length according to the model can be found out.If the arrival rate of left-turn vehicles is stable in a certain period of time,the minimum green time and the maximum red time of left-turn phase of the left-turn waiting area can be obtained.The result provides a theoretical basis for set up left-turn waiting area.