Study On Urban Road Network Evolution Laws Based On Complex Network Theory

Urban road transport network is the infrastructure of urban development and construction, which is typically a complex network composed of road systems, social systems and traffic systems. Using the method of complex network theory to study the topological characteristics of urban road network, analyzing the dynamic behavior of traffic on the road network, revealing the evolution of the development of urban road network, it favors us to understand the operating mechanism of urban road traffic system basically and discover the root causes of urban traffic problems Then we can provide some scientific decision-making methods for urban transportation planning and traffic design.In this paper, we use the complex network theory combined with traffic engineering, computer simulation and other related scientific and technical methods to analyze the topological characteristics of urban road network.Then we build a corresponding model of network evolution,based on related data to explore and understand the evolution of urban road transport network.By drawing on the evolution characteristics of road traffic network of Chengdu,we establishe the "chessboard"shaped city road traffic network evolution model,"chessboard and radiation" shaped city road traffic network evolution model,"chessboard and radiation and circle"shaped city road traffic network evolution model.The computer simulation shows that, in the "chessboard" network evolution model,the average path length increased linearly with the evolution of time,average degree of network also showed an increasing trend.Network clustering coefficient has been maintained for0.In the "chessboard and radiation" network evolution model,radiation into the average degree of network gradually decreased to a certain level,the distribution of node degree distribution have no obvious characteristics.In the"chessboard and radiation and circle"network evolution model, the clustering coefficient grows rapidly in the network with the ciecle roads joining in,and there are also some nodes with high degree in the network.The node with high betweenness will be easily linked by other neighboring nodes on the loops.When it’s tough to meet the traffic demand,in order to protect these nodes with high betweenness,we bulid a overpass and caused some nodes getting a high degree..