Research On Signal Control Of Oversaturated Intersection Group Based On Traffic Transfer

Nowadays there will be more or less a traffic congestion phenomenon in the domestic city road network.Especially in the economic situation is relatively good in the city,the frequency of traffic congestion happening is very high,so the over-saturated state is common.The inconvenience caused by traffic congestion has aroused general concern of the society.The urban traffic network is composed of several intersections.Accordingly,it will improve the efficiency of vehicle driving in urban area and solve the problem of urban traffic congestion effectively when we take effective control method for over-saturated intersections.Terefore,this paper will take intersection group as the research object,and make correlation studies on the definition of intersection group,the analysis of over-saturated traffic characteristics and the control strategy of over-saturated intersection group.Firstly,this paper introduces the concept of intersection group and the form of intersection group in urban road network,the basic parameters and related performance indexes when the intersection group was controlled are analyzed.Then,explaining the definition of over-saturated traffic,and combining observed data to analyze over-saturated traffic characteristics.Secondly,this paper illustrate the necessity of defining the range of intersections and the types of common intersection groups.After that the intersections of the urban road network is divided into several intersection groups based on the dividing principles and the index.On the basis of the set of several intersections,using the grey relational analysis to distinguish the key intersection by relevant traffic parameters.Through calculating the correlation degree between the key ingtersection and adjacent intersections,the traffic impact area of the key intersection is determined,and the intersection groups which were set before is optimized.Thirdly,the signal control strategy for over-saturated intersection group is put forward starting fron the generation process of over-saturated traffic phenomenon,aiming at evacuating the congested traffic flow of over-saturated intersection group.Taking queue length as a defining control transformation condition,the concept of transfer traffic flow is introduced,this paper presents a method of car flow transferring based on actuated control at the key intersection.This method can evacuate congested vehicle flow.By selecting the indexs of correlation to determine the link which between the key intersection and its adjacent intersections,the signal control method implemented in the upper and lower reaches of the key intersection is designed in detail.Finaly,taking the road network of Qujing in Yunnan as the verification object.This paper uses the traffic simulation software VISSIM to realize the simulation verification of the signal control method of the over-saturated intersection group.The effectiveness of the researchs of this paper is verified through comparing and analyzing the simulation results with the current signal timing scheme.