长区间掉头车辆特性分析及其安全评价

Traffic characteristics and safety analysis of long interval U-turn intersections

为了探讨掉头车辆在长区间掉头情况下的运动和安全特性,基于掉头车辆在典型位置的实测数据,运用概率论和数理统计知识对掉头车辆的轨迹和交通特性进行了分析,并建立了掉头轨迹模型。以后侵入时间(PET)为指标,利用交通冲突技术,研究掉头车辆的安全特征。本次研究得出了3个结论:首先,长区间掉头车辆与交叉口内掉头车辆的车头时距差异性显著,长区间掉头车辆的车头时距稳定性差,车辆的释放受掉头车流影响干扰严重;其次,长区间掉头车辆掉头起始位置分散,掉头轨迹分布服从二次函数分布;最后,长区间掉头车道的设置会增大交叉口车流之间的干扰程度,进而导致与对向车辆发生的冲突次数增加;长区间掉头的冲突类型中,交叉冲突的比例最大,交叉口内掉头的冲突类型以追尾冲突为主。上述研究结论有助于提高长区间掉头车道的安全性。

In order to explore the motion and safety characteristics of the U-turn vehicles at long-range Uturn intersections,based on the measured data of the U-turn vehicles at typical locations,we analyzed the characteristics of the U-turn vehicle's trajectories and traffic parameters with the help of probability theory and statistical knowledge,and established the U-turn trajectory model.We used traffic conflict technology(TCT)and take post encroachment time(PET)as the indicator to study the feature of vehicles security of U-turn vehicles.Three conclusions are drawn from this study.First,there is a significant difference in the headway between long-range U-turn vehicles and those at intersections without opening:the stability of the headway of long-range U-turn vehicles is weak,and the release of vehicles is seriously disturbed by the turning flow;Secondly,when turning around at a long interval U-turn intersection,the starting position of vehicle turning is dispersed and the distribution of U-turn trajectories is quadratic distribution.Third,the setting of long interval turning lanes will increase the interference between traffic flows at intersections,thus increasing the number of conflicts with vehicles in the opposite direction.Cross-conflict accounts for the majority of conflicts in long interval U-turn intersections,and rear-end collision is the main conflict type in U-turn intersections without opening.The above research conclusions are helpful to improve the safety of long interval U-turn intersections.