Study On The Method Of Setting Right U-Turn Lane At Intersections

With the intensification of urban development in China,the number of large public buildings in areas along the road is constantly increasing,making them important traffic generation and attraction points,but at the same time,the phenomenon of road traffic congestion has also increased sharply.Some road network planning is not reasonable.There are branch roads or roadside building exits within a short distance upstream of the intersection,and a large number of U-turn vehicles converge on the main road and need to continuously cross multiple lanes within a short distance section to make U-turn,increasing conflicts with through vehicles and reducing the traffic efficiency of the intersection,especially during peak hours.In order to solve the traffic problems caused by continuous lane changes of U-turn vehicles in close sections of intersections,a method of using the right U-turn lane is proposed.Right U-turn lane has been used in some cities in China,but it is not clear how the lane change behavior of vehicles will affect the traffic flow in the section after the right U-turn lane is set at the intersection,In addition,there are no clear setting parameters for the traffic supporting facilities with right U-turn lane in actual road traffic applications.Therefore,this thesis has studied the setting methods of right U-turn lane at intersections.Firstly,this thesis analyzes the traffic flow characteristics of the intersection entrance lane,including headway,vehicle queuing,lane saturation,and vehicle operation characteristics in the upstream impact area,based on the data from the intersection field survey;This thesis expounds the concept and setting form of right U-turn lane,defines the scope of research,and analyzes the operational characteristics of vehicle flow at intersections with conventional U-turn lane and right U-turn lane.Secondly,the vehicle lane changing behavior is described.According to the different purposes and motivations of drivers,the vehicle lane changing behavior is divided into free lane changing and forced lane changing.The lane changing characteristics at different stages of the vehicle lane changing process are analyzed.The impact on the vehicle lane changing behavior is analyzed from the perspective of people,vehicles,roads,and traffic environment,and the correlation between the vehicle lane changing behavior and traffic flow is analyzed,This provides a theoretical reference for subsequent research.Thirdly,based on the cellular automata theoretical model,a lane changing behavior model of vehicles at rightward intersection of U-turn lane is constructed.The intersection section is divided into three zones: free driving zone,forced lane change zone,and prohibited lane change zone,with different lane change rules set;By simulating the lane change model,the traffic impact of different lane change decision points on the road segment is analyzed and obtained,providing a theoretical basis for the setting of traffic signs below.Then,the setting method of right U-turn lane intersections is studied.The applicable conditions for right U-turn lane is analyzed,including basic setting conditions and intersection scale;The length of the guiding lane line and the position of the guiding arrow are obtained using queuing theory;By analyzing the psychological process of drivers after seeing traffic signs,a leading distance model for guiding lane signs is obtained;Based on the Webster timing method,a signal control model for right U-turn lane intersections is constructed.Finally,this thesis analyzes an example intersection in Mianzhu City,and constructs a simulation road network of conventional intersections and right U-turn lane intersections using the VISSIM simulation platform.The results show that the average queue length of the intersection after setting the right U-turn lane has decreased by 6.13 m,the maximum queue length has decreased by 18.57 m,and the delay time reduction rate is 25.74%.Setting the right U-turn lane has alleviated travel pressure and effectively improved the traffic efficiency of the intersection,which has certain guiding significance.