Applicability Analysis Of Four-Way Displaced Lefft-Turn Intersection Considering Collaborative Control

Entering a new era,the scale of China’s cities,motorization level and road construction are constantly developing and changing,and the left-turn traffic flow conflicts at certain intersections are serious and the normal management means are less efficient.Therefore,unconventional displaced left-turn designs are proposed and applied to actual intersections.At present,most of the studies on displaced left-turn have been conducted from a qualitative perspective,and the applicability of displaced left-turn has not been explored in depth.How to analyze the applicability of displaced left-turn design systematically from the quantitative level is the key of this paper.Firstly,this paper starts from the basic theory and explains the spatial and temporal characteristics of traditional planar intersections and the organisational characteristics of left-turn traffic flow.On this basis,the definition,types and traffic characteristics of displaced left-turn intersections are introduced in detail to prepare for the comprehensive optimization design of four-way displaced left-turn intersections.Secondly,a four-way displaced left-turn intersection comprehensive optimization design method is proposed.Starting from the setting principles and conditions and combining the geometric characteristics of the displaced left-turn intersection,a four-way displaced left-turn intersection spatial canalization optimization design method is proposed,including the calculation models of rightturn lane widening,displaced left-turn storage lane length and section left-turn lane segment length.Based on this,the two-phase(scheme a)and three-phase(scheme b)signal cooperative control optimization models are constructed from the traffic organization rules,green light duration and signal constraints,respectively,by analyzing the cooperative control principle and traffic flow characteristics and taking the minimum vehicle average delay as the objective function.Thirdly,the applicability analysis of the four-way displaced left-turn intersection is performed.In order to determine at a quantitative level which intersections are more effective with a displaced left-turn design,using delay and number of stops as evaluation indicators,the two-phase(scheme a)and three-phase(scheme b)are compared and evaluated in terms of saturation,number of displaced left-turn lanes,and different traffic flows,and the applicable conditions of the two options are obtained under different conditions.Finally,in order to verify the validity of the applicable conditions for displaced left-turn,Tuanjie Avenue-Renhe Road intersection in Wuhan City is selected as an example,and the intersection is investigated in the field in terms of traffic flow,spatial layout and signal timing,respectively.Based on this,a four-way displaced left-turn intersection comprehensive optimization design modification is carried out for this intersection,and the simulation platform for the current intersection,twophase(scheme a)and three-phase signal cooperative control(scheme b)are established respectively by VISSIM software,and the traffic flow data are imported for simulation evaluation.The results show that scheme a and b are effective in relieving intersection congestion,and scheme b is more effective than scheme a,further verifying the superiority of the four-way displaced left-turn intersection integrated optimization design method.