Quantitative Study on the Influence of Pedestrians Twice Crossing in the Left-Turn Phase at Multi-Phase Signal Intersection

This paper studies a frequent violation at multi-phase signal intersection of Beijing, that large number of pedestrians twice crossing street in the left-turn phase. Based on a large number of measured data, the influence of this violation on intersection safety is analyzed by using the theory of traffic conflict. To solve the violation, some strategy and methods have also been summarized. As an important link in City Road system and a crucial section of the whole road net, the intersections in the city act as the nodes connecting the crossing roads and control the vehicle volume. Due to the complexity of traffic participants and the high concentration of traffic flow, traffic accidents are very liable to occur in the crossings. According to the traffic accident statistics in China (2008), there are 46148 traffic accidents in crossings, taking account of 17.40% of the total number of the traffic accidents and leading to 9549 death. (Ministry of Public Security, 2009) Therefore the studies on the influence factors of crossings safety have been considered as an urgent need. Multi-phase signal has been adopted in increasing amount as an effective method to improve the traffic safety. In this system, the left-turn phase is put forward to separate the straight flow and left-turn flow to different time sections, thus to decrease the traffic confliction points. However, the implementation of left-turn phrase will to some extent extend the waiting time for the pedestrians passing through the streets. The pedestrians are likely to break the traffic rules and cross the roads regardless of the traffic signal if the waiting time is too long or the waiting crowd has reached saturation. Normally they no longer cross the road along with straight flow, but first move to the side-sections of left-turn lanes, then go across the intersection by taking the gaps between left-turn flow and wait until left-turn phase finishes. (Shown in Figure.1) The violation of signal will lead to more conflicts between vehicles and pedestrians hence have a negative influence on the whole safety issues.