Study On The Capacity Of The Left-Turn Waiting Area At Signalized Intersection

Signalized intersection usually is the bottleneck of urban road traffic capacity, and the left turn traffic flow cause more problems with intersection’s efficiency and safety. The crossing conflicts between left turn and through movement vehicles will significantly reduce the intersection traffic capacity and operation efficiency. The vehicle queuing and traffic congestion caused by high left turn traffic demand, lead to tremendous energy waste and air pollution for big cities. Therefore, how to improve the traffic capacity of the left-turn lane, has become one of the most important research topics for urban traffic management.In this paper, integrated application of the traffic engineering, mathematical modeling, system engineering and the multi-disciplinary theory is used to analyze the application of left-turn waiting area. Through theoretical analysis, field survey and data processing calculation, and by analyzing the operation characteristics of left-turn traffic, the capacity of left-turn waiting area is investigated, mainly including the following aspects:1. The characteristics of the left-turn traffic flow were studied theoretically. It is found that using left-turn waiting areas to channelize left-turn traffic flow, can improve the intersection’s left turning traffic capacity and better meet the needs of the left-turn traffic through the intersection.2. The classification of left-turn waiting areas, and channelizing conditions for the left-turn waiting area were analyzed.3. Designed a detailed filed data collection plan, collected and analyzed the real traffic data of several major intersections in Shanghai.4. Based on field data analysis, several application improvements were suggested.5. The traffic capacity calculation methods for the signalized intersection were summarized. And a revision of the common capacity calculation method was proposed. The traffic data collected in several major intersections of Shanghai was input into the modified capacity calculation formula for validation purpose.