Research On Spatial And Temporal Resource Optimization Method At Contraflow Left-turn Intersection

With the increasing number of motor vehicle holdings in our country,the traffic problem characterized by intersection congestion has become more and more serious nationwide,and traditional intersection design and optimization methods are increasingly unable to meet the rapidly growing traffic demand.In order to alleviate intersection congestion,in recent years,the public security traffic management department has explored a variety of unconventional traffic organization methods in practice.The contraflow left-turn lane design(CLL),as a kind of unconventional traffic organization,can provide additional space traffic rights for left-turn traffic,thus improving the traffic efficiency of intersections.However,the implementation of the CLL has special requirements for the spatial and temporal resource conditions of intersections,due to the lack of corresponding technical standards,the implementation of the CLL in practice mainly relies on the actual work experience of traffic management departments,and lacks the support and guidance of quantitative research.To some extent,it hinders the promotion and application of the CLL intersections.On the premise of ensuring safety and efficiency,this paper studies the optimization method of the spatial and temporal resources at the CLL intersections based on practical application.The main contents of the paper are:Firstly,the paper clarified the basic characteristics of CLL intersections,which explains its traffic operation mode,time and space design principles,setting conditions and existing safety risks.Then on this basis,the setting method of the CLL was analyzed and studied from both spatial and temporal aspects.Spatial aspect: the calculation method and setting standard of the geometric parameters of the CLL intersection were given,including the number,width,length and opening length of the central separation zone;combined with relevant design theory and standard specifications,the traffic control facilities at the CLL intersection were standardized.Time aspect: two CLL intersection signal phase schemes were proposed,the coordination relationship between the main signal and the pre-signal was explained,and the phase difference calculation method between the main signal and the pre-signal was given;subsequently,the capacity,delays and stop times of CLL intersections were analyzed,and a multi-objective signal timing optimization model was constructed on this basis;the fuzzy compromise planning method was introduced,and the dimensions of each objective function in the optimization model were processed,the weight of each objective function was determined by the fuzzy preference method,and the multi-objective signal timing optimization model was transformed into a single-objective signal timing optimization model.and the solution was solved based on genetic algorithm.Finally,taking the intersection of Beixin Road and Jianshe South Road in Tangshan City as the paper case,using the optimization method of the spatial and temporal resources proposed in the paper,the case intersection was transformed by CLL,and using VISSIM simulation software to simulate and evaluate the operation benefits of the front and rear transformation intersection,which verifies that the methods proposed in the paper were feasible and effective.The paper studies the optimization method of spatial and temporal resources at the CLL intersections,which is the basic research for formulating the organizational standards of unconventional intersections;it is helpful to improve the scientific nature of intersection management;serves the practical work of grassroots public security traffic management,and contributes to our country’s traffic harmony and social harmony.