Optimization And Evaluation Model Of Urban Traffic Microcirculation System

In recent years,the high number of motor vehicles and the high frequency of passenger travel have brought a serious burden to the transportation infrastructure and put forward higher requirements for road capacity.In the face of this rapid growth in traffic demand,the Chinese government and traffic management departments have also made corresponding efforts.However,efforts at any level only focus on the expansion or improvement of the city’s arterial circulation system,while ignoring the construction of branch road systems,making it impossible to efficiently cooperate with all levels of roads in the city and to maximize the use of transportation facilities.In response to this problem,some scholars have opened up a new exploration direction to solve urban traffic congestion——carrying out traffic microcirculation transformation.The traffic microcirculation theory slightly transforms and utilizes existing branch roads and narrower roads,and organically connects them with existing arterial roads to form an efficient traffic microcirculation system.The excess traffic pressure on arterial roads is evenly diverged into the traffic microcirculation system,the existing road resources are rationally utilized,and the contradiction between urban traffic supply and traffic demand is solved.Therefore,how to construct a traffic microcirculation system and how to judge whether the construction of the traffic microcirculation system is reasonable is an urgent problem to be solved in this new direction of exploration.This paper analyzes and summarizes the existing traffic microcirculation theory,and on this basis,proposes a two-layer optimization model of the urban traffic microcirculation system and an evaluation model of the urban traffic microcirculation system,which can provide a reference for constructing a reasonable traffic microcirculation system.First,through the blood microcirculation in the medical field,fundamental connotation and working principle of urban traffic microcirculation are defined,and on the basis of introducing the classification of traffic microcirculation,this paper is limited to the study of regional and long-term traffic microcirculation with motor vehicles as the main body.The analysis shows that the urban traffic microcirculation has functional characteristics such as alleviating the traffic pressure on arterial roads,improving the utilization rate of branch roads,optimizing the road network structure,coordinating urban planning and construction,revitalizing existing parking resources,and benefiting residents in the area to travel.and further discussion of the traffic flow characteristics,setting conditions,management characteristics and optimization goals of urban traffic microcirculation.Second,a two-layer optimization model of the traffic microcirculation system is constructed.The upper-layer model is built targeting on maximizing the average travel speed under the constraints of reconstruction expense and traffic capacity,which determines the roads to be selected as traffic-chunting channels for constructing traffic microcirculation system and the degree of reconstruction;the lower-layer model establishes the minimizing function of total impedance of the road network,through combining the intersection delay with the travel time of the road section,to assign OD traffic under the premise of meeting the requirement of upper-layer model.And a solving algorithm for the model through genetic algorithm is established.Third,the gray correlation analysis method is used to eliminate the dimensions of each evaluation index and to select evaluation index suitable for evaluating the urban traffic microcirculation system;and the urban traffic microcirculation system evaluation model is proposed based on the fuzzy analytic hierarchy process,and the fuzzy comprehensive evaluation method is used to blur the boundaries of each grade comment,and the analytic hierarchy process is used to determine the weight of each evaluation index.Thereby the overall evaluation value for the planned road network is obtained.Finally,the model and algorithm proposed in this paper are verified by taking the Xinmart area of Daqing City as an example analysis object.The experimental analysis shows that the overall evaluation value of the road network is increased from 55.30 to 70.72 after the transformation of the traffic microcirculation.The results show that the model and algorithm proposed in this paper are effective.