Study On Urban Road Network Carrying Capacity Based On Self-Organization Theory

Along with the increase in the number of vehicle possession, urban traffic congestion has gradually become the major problems that restrict the development of the modern city.When the road network traffic reaches a certain level, it will show self-organized criticality, at this time, tiny disturbance may lead to congestion accidents in large area. Through the research on the road network carrying capacity, before the road network reaches the self-organized state, taking appropriate control measures to destroy the self-organized state can prevent congestion accidents of road network in a certain extent. However, the urban road has complex structure and many influence factors, in addition, there existing relatively fewer mature theory and methods research on the road network carrying capacity, which poses a particular difficulty on the research of road network carrying capacity. To solve the above problems, combined with the characteristics of urban road traffic operation, the paper puts forward a new method to study road network carrying capacity using self-organization theory. The main contents are as follows:(1) According to different road attributes in road network, referring to the judgment method of traffic congestion of domestic and foreign, combined with the actual survey of Beijing city road, the paper gives judgment standard of traffic phase of urban expressway and road section respectively. Based on that, combined with the lane length ratio of urban expressway and road section, the paper gives judgment standard of traffic stage of road network, which is regarded as judgment standard of traffic congestion. Then according to judgment standard of traffic stage, the paper provides definition of road network carrying capacity and math formula.(2) According to the characteristics of urban road network, the paper constructs the dissipative structure model of urban expressway and road section combined with road grade and layout, traffic control and other factors. Based on that, considering the mutual influence between various sections in the road network, the paper constructs dissipative structure model of road network to simulate vehicle operation situation of urban road network, judge the road network congestion state and solve road network carrying capacity.(3) With dissipative structure model of road network, the paper conducts measuring research on road network carrying capacity, and then, the paper performs simulation experiment on road network with the help of VISSIM, verifying the usability that dissipative structure model of road network apply into road network carrying capacity by comparing the two kinds of model results.(4) Changing the parameters of input traffic and road structure and other factors influencing the road network carrying capacity, the paper performs simulation experiment using VISSIM, and compares the simulation results with the results before changing parameters, in order to provide reference for traffic management departments to take measures to improve the road network carrying capacity.