Study On Traffic Safety, Efficiency And Intervention In Weaving Area Of Interchange

With the traffic demand increase continuously and the land limit in urban area, more and more interchanges appeared with adjacent exits and entrances, where vehicles need twice merging, diverging or weaving operation, and the traffic safety and efficiency of these areas are lower than others. As the classic adjacent exits and entrances, weaving areas are the keystone and difficulty of traffic study. Weaving areas are dynamic areas, where vehicles change lanes frequently to complete merging and diverging operations in a short distance, and they form the accident black spot and bottleneck of urban expressways.Firstly, this paper confirms the studying object by analyzing the impacts of waving areas, such as weaving configuration, weaving length, width, volume, volume ratio, weaving ratio and velocity, etc.. According to summarizing and analyzing the status quo and its problems, especially TCT (traffic conflict technology) and its application in weaving areas, it extends the definition of TCT by VISSIM, and puts forward TCT based on VISSIM simulator and its application procedure. An orthogonal experimental design is developed by assuming the change range of every factor in order to analyze the relationship between traffic conflicts and the factors respectively, and a multi-regression model of traffic conflicts is established and tested. Although TCT has been used in weaving areas, the index which is suitable for intersections can't reflect the conflict characteristic in weaving areas. This paper sets conflicts per vehicle kilometer which adapt to weaving characteristic as traffic safety index to evaluate traffic safety by Clustering analysis and Fuzzy method. Finally, the paper analyzes the traffic intervention of weaving areas considering traffic safety and efficiency, especially the road conditional and traffic flow interventions. Taking an example of Youyi Avenue interchange of Wuhan Changjiang River Tunnel, reasonable weaving length is studied by difference analysis method using conflicts, relative conflicts, conflict intensity and capacity as traffic safety and efficiency indices respectively; the paper selects conflicts per vehicle kilometer the traffic safety index, traffic flow rate, delay per vehicle of weaving section and ramp as the efficiency indices to simulate three common intervention measures i.e. yield sign, main line speed limit and ramp metering, and confirms the traffic flow intervention under different traffic demand. The result shows that main line speed limit should be added to yield rule in weaving areas to increase traffic and efficiency when traffic demand is small; if demand increases to some degree, entrance ramp metering need to be used to limit the traffic flow to main line of weaving areas.