Research On Applicability Of Traffic Conditions At Cross-shaped Continuous Flow Intersections

Intersections serve as nodes of the urban road traffic network and are also areas where traffic flows in all directions are prone to conflict.The increase in delay at intersections and the reduction in traffic capacity will cause problems such as traffic congestion and traffic accidents.Reducing the delay at intersections is crucial to improving the capacity of the entire road network.The delays at the intersections depend on the delays of the entrance roads.The traffic flow at the entrance roads consists of left turn,straight run and right turn.The main reason of the excessive delay in the e ntrance roads is the improper handling of the left turn traffic.In order to reduce delays in access roads and improve intersection traffic capacity,the traffic management department has implemented a variety of left-turn traffic processing methods,such as improving signal timing,canalization,increasing the number of left-turn lanes,prohibiting left-turning,etc.,however,As the proportion of turning left traffic increases,the implementation of these traditional left-turn traffic treatments is less than ideal.In recent years,foreign scholars have proposed an intersection of non-conventional left-turning design methods-Continuous Flow Intersection.This non-traditional intersection method for handling left-turn traffic is as follows: Before arriving the main intersection,the left-turn vehicle is guided to the left side of the opposite straight lane through the guidance of marking lines.Under the effect of signal control,the main intersection is allowed to release the left-turn phase and the straight-line phase at the same time without conflict.The traffic flow of the corresponding entrance road at the intersection can pass through the intersection continuously with less delay.The operation mode of the right-turn traffic and direct traffic at this new intersection is the same as that of the traditional intersection.It only changed the operating mode of the left-turn traffic.Therefore,the study of the traffic suitability of the continuous-flow intersection mainly depends on the setting conditions of the left-turn lane.The research on the application of this new intersection is mainly concentrated in foreign countries,and there are few in China.In particular,there are fewer researches on the setting conditions of the left-turn dedicated lane at the intersection of continuous flow and the selection of relevant geometric design parameters.The setting conditions for continuous flow left-turn storage lanes are the focus of research,and the length of left-turn storage lanes is mainly affected by the queue length of left-turn vehicles on the stop line.Therefore,this article mainly takes the left-turn storage lane as the research object.Through analyzing the relationship between the queue length of the left-turn vehicle at the upstream of the inte rsection and the length of the left-turn storage lane,the setting conditions for determining the continuous-flow left-turn storage lane are studied.The main work of this paper is as follows:(1)Study on the advantages,disadvantages and application stat us of continuous flow intersections.The basic definitions of continuous flow intersections and the operation modes of traffic flow are briefly described.By analyzing the design conditions of foreign continuous flow intersections,including road conditions and traffic conditions,the basic setting conditions of continuous flow intersections are summarized,factors affecting the applicability of left-turning lanes.(2)Taking the length of the left-turn storage lane as the research object,analyzing the influence of the signal cycle and the left-turning dedicated phase on the length of the left turn queue at the upstream of the continuous flow intersection,determine the key influencing factors,and carry out the sensitivity analysis and quantitative analysis of the key factors.The limit values and critical values of the left-turn traffic volume and the left-turn queue length were obtained,respectively,to study the setting conditions for the length of the continuous flow left-turn storage lane,and to establish a theoretical calculation model for the length of the continuous flow left-turn storage lane.(3)Actual case verification,taking the typical crossroad in Suzhou as a case,and analyzing the road and traffic conditions at the intersection to determine whether it meets the setting conditions of the continuous flow Intersection,and calculating the setting of the left-turn storage lane according to the calculation model established previously.The length was then converted into a continuous flow intersection.Using VISSIM micro-simulation,the running status of the intersection before and after the reconstruction was simulated,and the average delay and queue length were used as evaluation indicators to verify the rationality of the design of the le ngth of the continuous flow left-turn storage lane.In this study,through comparative analysis before and after the transformation,it was found that the delay of the left-turn traffic flow after the transformation was significantly reduced,thereby increasing the capacity of the entrance road and achieving the expected results.It tries to provide a certain degree of reference for the research on the setting conditions of the length of the domestically left-turned storage lane at the continuous flow intersection,and provides a certain reference for the relevant design in practical application.