共用左转车道通行能力比较分析

在不同车道配置、信号配时和直左交通量的情况下,将两种研究共用左转车道通行能力的方法(即1994《美国通行能力手册》和中国《城市道路设计规范》中的方法)进行了比较分析。结果表明:随着左转交通量的增加,共用车道的通行能力相应降低;当周期长从60s增加到90s,具有相同有效绿信比的进口道通行能力有所降低。具有相同总绿信比的长周期的通行能力略有增加;当左转交通量超过一个定值时,进口道的总需求交通量超过通行能力。改进信号相位相序,实施左转保护相位可解决这一问题。

Comparative analysis on capacity of shared through and left turn lanes

Two methods for evaluating the capacities of shared through and left turn lanes from《1994 US highway capacity manual》and《design criteria of city street in China》 under various lane configuration,through and left turn volumes, and traffic signal timings were comparatively analyzed.Results show that when the left turn volume increases, the total traffic volume of shared through and left turn lanes decreases correspondingly.When the traffic signal period increases from 60s to 90s,the approach traffic capacity decreases under constant effective split.For constant total split,traffic capacity with long signal period increases slightly.When the left turn volume exceeds a threshold,the traffic demand will exceed capacity on the approach.In order to solve the problem,the signal phase design should be improved, including to implement a left turn protective phase.