Study On The Evolution Of Urban Public Transport Network

The urban public transit network has gradually developed into a complex network system,which is the core of the public transportation and the rail transit network. In this paper, based on complex network theory, reference system dynamics and mean field theory, in-depth study of the evolution mechanism of city public transportation network, constructing new network evolution model with public traffic construction development characteristics, further research of city public traffic network evolution.Firstly, the evolution of urban public transport network can be divided into three stages:backbone network, weaving network and hybrid network. According to the principle of system dynamics, the internal structure of the network point of view, analysis of factors the evolution of city public transportation network optimization, including four aspects of internal public traffic demand, the supply of public transport, traffic diversity and network development, the causal relationship between different factors and feedback through the chain, negative feedback chain of public transport demand and the economy the positive feedback of public transportation and economic supply chain. Based on this, the dynamic evolution model of urban public transport network evolution based on different factors is established.After the construction of the ideas and methods of the classical WS small world model and BA model, combined with the city public traffic network evolution features in the process,put forward connections between nodes connected domain and mixed two evolution mechanism, construct the evolution model of mixed connection based network connected domain. Application of system dynamics and mean field theory, the evolution of the degree distribution of model expression derived network, network evolution simulation model by using Pajek along with the increasing scale of the network, the network degree distribution curve by the power law function gradually evolved into exponential function, reflected by internal network structure is not balanced gradually evolution to the network state, and on the network steady state analysis of the further elaboration.Finally, the public transit network in three largest city Shanghai, Guangzhou and Hongkong, as the research object, the research on degree distribution curve of public transport network and rail transit network, combined with the trend of the average degree of the rail transit network and the number of bus network for nearly ten years, found that the public transit network is optimizing as expanding. Then based on the network structure model,propose bus and rail transport connection network, the concept and calculation method of the degree of network connectivity is defined. The empirical results show that the distribution curve of the degree of singularity is exponentially distributed, and the evolution of the network is random. By comparing the results of the empirical data and the model fitting,the paper describes the actual process of evolution of the connection network to the steady network, and provides reasonable suggestions for urban public transit network development planning.