Research On Vehicle Congestion Based On Three-phase Traffic Flow Theory

In recent years,the rapid development of Chinese economy and the rapid increase in the number of car ownership have improved the quality of life of the people.Advanced transportation brings us a lot of negative impacts on our lives.As a typical traffic problem,traffic congestion not only causes economic losses,but also aggravates environmental pollution.In this paper,we study the relationship between traffic congestion and phase transition,using cellular automata theory and the MATLAB as tools,based on the three-phase traffic flow theory.Firstly,using the basic theory and the three-phase traffic flow theory analyzed the measured results and introduced the advantages of the three-phase traffic flow theory.Secondly,the basic assumptions of three-phase traffic flow theory,traffic delay,traffic phase and phase change process are introduced in detail.Thirdly,the basic knowledge of cellular automata is analyzed based on its structure,characteristics and classification.Fourthly,the average number and average length of traffic congestion group are defined by the programming language.Finally,the simulation model is used to calculate the average number and length of congestion group.The main points are summarized as follows:(1)Firstly,this paper introduces the research significance of traffic flow theory,and reviews the basic knowledge of traffic flow theory,then puts forward the definition of traffic jam group,and adds the relevant definition to the classical model research.(2)The VDR model of congestion detection is simulated and analyzed and find that the number of vehicle congestion group and the average length of vehicle congestion group appears when the speed phase transfers.With the increase of density,the number of vehicle congestion group is increasing,but the growth rate is getting smaller and smaller,at this time,the average length of the average congestion group increases in a small range,indicating that the density range is mainly small congestion groups.(3)Based on the research of the basic graph model,the paper studies the three phase traffic flow model.The KKW model is chosen as the research object in this paper to study the relationship between traffic congestion and phase transition.Unlike the previous model,the KKW model is used to refine the cell,its length changed from 7.5m to 1.5m.Relatively small cell size can truly reflect the relative motion between vehicles,reduce the deterministic deceleration,and can accurately describe the vehicle speed and position changes.In addition,the congestion detection model is optimized to make it more realistic.After adding the congestion detection subroutine in KKW,the traffic jam model is simulated.Except having a relation between the first-order phase transition and congestion group number and the average length of congestion,when the first-order phase transition,the number of traffic congestion group reached the maximum.The average length of congestion group began to increasesignificantly,at this time,the small group gathered to be a large traffic jam group.Finally,the whole road was occupied with vehicles.