Research On Sub-Area Division And Boundary Traffic Control Strategy Of Urban High-Density Road Network

Nowadays,urban high-density road network has become one of the main modes of urban road network planning and construction.Because the high-density road network is mostly located in the central area of the city and integrates the functions of residence,entertainment,business office,education.And the total amount of traffic travel in these areas is large and the residents travel is concentrated.At the same time,the high-density road network has the characteristics of narrow road width and short road spacing.When the traffic flow into the road network is too large,traffic congestion may occur,resulting in a decrease in the operating efficiency of the road network.These problems put forward new requirements for the control of traffic flow in the high-density road network.Therefore,this paper takes the high-density road network as the research object,summarizes and analyzes the structural characteristics of the high-density road network,studies the subdivision method of the road network,and proposes a method for identifying and classifying the operating status of the road network sub-area,establishes a traffic coordination control model at the boundary of the road network sub-area to provide a reference for the formulation of traffic control strategies,and by controlling the input and output of traffic flow at the boundary of the road network sub-area,the purpose of reducing vehicle delay in the road network can be achieved.Firstly,this paper analyzes the structural characteristics of the urban high-density road network.The urban high-density road network is mainly to serve business and daily travel in function and the road width is narrow and the road grade gap is small.The layout of the road network is mainly grid-like,the road spacing is short.And this paper analyzes the structural characteristics of road network density and road spacing in typical high-density road network areas such as Shanghai Bund and Tianjin Central Park.Then,taking Nanjing Hexi CBD regional road network as an example,a high-density road network simulation environment based on VISSIM software is built.Secondly,the sub-division and evaluation method of road network is proposed.Selecting the central position of the road,the average density of the road section,and the average traffic flow of the road section as the clustering indicators,a sub-division method of the road network based on the clustering algorithm is proposed,and the road network MFD curve is fitted with the road network weighted traffic flow and the road network weighted density.And the result is quantitatively evaluated by using sum of the squared errors and coefficient of determination.The empirical analysis results show that after the road network sub area division,each sub-area can get an ideal road network MFD,which lays a foundation for the control of road network sub-areas.Then,the classification and identification method of traffic state of regional road network is proposed.Considering the different influence degree of different road sections on the traffic state of regional road network,the influencing factors include road section grade,road section length and road section degree,and the calculation model of road section weight is established.On this basis,the calculation model of road network unblocked rate and road network spatial load margin based on road segment weight is constructed.The traffic state division process of regional road network based on NJW spectral clustering algorithm is proposed,and the traffic state recognition of road network sub-area is realized by constructing SVM multi classifier.The empirical analysis results show that the traffic state division of road network sub-area based on NJW spectral clustering algorithm is reasonable,that also can be accurately identified by using SVM multi classifier.Finally,a traffic control model of road network sub-region boundary is established.The boundary control timing of the road network sub-area is determined according to the traffic state of the road network sub-area.Taking the change of the cumulative number of vehicles in the sub-area of the road network as the state transition variable,a vehicle flow balance equation is established.And taking the minimum vehicle delay as the goal,and taking the optimal cumulative number of vehicles in the sub-areas of the road network and the traffic capacity of the sub-areas as the constraints,a traffic game control model of the boundary of the road network sub-area is constructed based on the game theory.The empirical analysis results show that the average delay of vehicles is significantly reduced after the boundary control of the road network sub-areas.At the same time,the influence of the sub-area boundary traffic capacity on the optimal boundary traffic control strategy of the road network is analyzed.