Research On Capacity And Level Of Service Of Signalized Intersections With Waiting Areas

Setting waiting area is a common traffic organization optimization method for urban road signalized intersections.In specific applications,due to improper setting of waiting area at some signalized intersections,it not only fails to effectively improve the capacity of signalized intersections and reduce vehicle delays,but also causes the increase of vehicle parking times and safety hazards.In view of this,this thesis studies the traffic organization design,traffic capacity and service level of signalized intersections,providing some reference for signalized intersections planning and design of waiting areas.The main work of this thesis is as follows:Firstly,by sorting out the changes of vehicle running before and after setting the waiting zone,the main conflict characteristics of different signal control modes were analyzed,and the geometric critical conditions for setting the waiting zone were proposed.Based on the theory of traffic wave and the law of vehicle queue dissipation at different saturation degrees of intersections,the critical conditions of traffic volume for waiting zones in different types of inlet lanes are proposed.Secondly,the video camera method is used to collect the geometric size,waiting area capacity,signal timing,vehicle running parameters and other information of five signalized intersections in Shijiazhuang City,and 11533 headway data are obtained.Based on the survey data,traffic operation characteristics of vehicles at signalized intersections with or without going straight were analyzed,such as saturated headway,starting loss time,tail clearance loss time and signal green interval time.The investigation results show that the saturated headway and tail-clearing loss time of vehicles do not change significantly after setting the waiting zone,but the starting loss time and the green interval time increase,and the starting loss time increases significantly with the increase of the waiting zone capacity.Then,the marking style and setting width of the waiting area are analyzed.According to the geometric critical conditions,the length of the waiting zone is determined.The distance between vehicles and intersection conflict point is used to adjust the green interval time and signal cycle.Based on the length of waiting zone and the running speed of queued vehicles,the delayed start model of waiting zone is established.On this basis,the traffic organization of waiting zone is optimized for Yuhua Road-Ping ’an Street intersection in Shijiazhuang City.The results show that the traffic organization design of waiting zone signal intersection in this thesis is feasible and effective.Finally,based on the traffic characteristics of the waiting area signalized intersection,the queuing dissipation law of vehicles before and after the waiting area is set up and the intersection delay model diagram,combined with the parking line method and Webster delay model,a calculation model of the capacity and delay of the waiting area signalized intersection is established,and the effectiveness of the model is verified.The influence of waiting area on capacity and service level of signalized intersection is analyzed.The results show that lane waiting zone can effectively improve lane capacity,reduce lane saturation and reduce average vehicle delay,so as to improve lane service level,and the greater the capacity of waiting zone,the more obvious the improvement effect.