Study On Optimization And Evaluation Of Signalized Intersection

As a gathering place for convergence, steering, and evacuation of the traffic flow,intersection is the key point of urban road network. It is not only the bottlenecks of urban roadnetwork, but also the origin of accident-prone sites and traffic congestion. It is important toensure the smooth flow of the traffic for the purpose of improving the capacity and operationof city road network. Therefore, to optimize the intersection is one of the most effectivemeasures to improve the capacity and operating efficiency of the road networkThe study is focus on the optimization of signalized intersection. Firstly, the trafficcharacteristics of signalized intersection are analyzed, which includes traffic flowcharacteristics, capacity, operating efficiency and safety features. These analysises are thetheoretical foundation for the intersections channelization and signal cycle optimization. Atthe same time, it provides four evaluation index of operating efficiency and security: theaverage delay, queue length, number of stops and the number of conflicts.Secondly, some optimization measures are proposed from the aspects of channelizationand cycle optimization. With regard to channelization, measures to different conditions areproposed for motor vehicles, non-motor vehicles and pedestrians based on the purpose ofoperation efficiency and safety. With regard to the signal cycle optimization, a new signalcycle optimization model based on the Webster delay correction is proposed. And the newcycle model can be applied to different traffic conditions. In order to evaluate the effects ofthe engineering measures, case studies were conducted in section3.5and4.3, and anevaluation method based on both simulation and statistical test is proposed. Finally, a casestudy of an intersection in Xi’an was conducted to verify the composite optimization measureof channelization and cycle optimization. VISSIM simulation and SSAM analysis were usedto obtain the evaluation indexes, and statistical test method was also used to evaluate theoperating efficiency and safety performance. This study can provide a reference forintersections improvement.