Chinese Urban Passenger Transport Network

People find that nearly all complex systems have the network structure.The complex network has become a hot issue in the field of current science.It simplifies the complex system as a set of vertices and edges.Vertices represent the units of the system, edges are representative of interactions between the vertices,each vertice and edge may carry a certain weight.The basic unit and the interaction of emperical systems may be multi-types and extremely complicated,so it is generally difficult to find the general rule which all types follow.We always hope to discover some kind of system the general statistics properties,and establish evolution model explaining its intrinsic dynamics mechanism.With the development of social economy,each kind of transportation network becomes practically important.So,many domestic and foreign,scholars have drawn great enthusiasm on this research.As we all know,only single traffic networks,such as bus network,airplane network and railway network,have been investigated empirically. However,passengers often have to change traffic tools and thus the traffic network actually is combined.Therefore an empirical study on a combined traffic network is necessary.The Yangtze River delta metropolis circle is one of regions which economy develop quickest,the export-oriented economy is most active,and urbanized level is highest.It holds the important strategic status in the development of national economic and society But the relative backwardness region transportation has affected the developing of economic integration of the Yangtze River delta metropolis circle.In this paper,as an example,we shall report an empirical investigation on the combined traffic network,which includes inter-urban bus network,railway network,river and sea ship network and airplane network in the Yangtze River delta metropolis circle from the viewpoint of complex network.We proposed two new statistical parameters: "incompleteness" and "convenience" for transportation network.We attempt to establish a simple transportation network evolution model.According to the 2004's GDP and population of cities in the Yangtze River delta metropolis circle,we forecast the total passenger flux between two cities using the gravity model.Considering the probability that people of the different wages level who choose the different transportation vehicle in the total passenger flux,we estimate the passenger flux of the different transportation vehicle.Then we present a transportation evolution model that node number is fixed,and edge number increases.The probability of a newly added edge considers the passenger flux of this kind of transportation vehicle between two cities,but also node weight defined the product of the multiplication of population and GDP of a city.The numerical results of model are good agreement with the empirical ones.Because transportation network scale of Yangtze River delta metropolis circle is small,the network statistics properties will be influenced by the area and geography factor.In this foundation,as another example,we study the combined traffic network of china including the intercity bus network,the railway network,and the airplane network. On unweighted and weighted networks,some statistical properties have been empirically investigated for each traffic network and the combined one.Degree distribution,weight distribution and strength distribution are all Shifted Power Law, holding different parametersα.The correlation of average nearest neighbors degree is assortative when degree is litterer than certain value,and is disassortative when degree is bigger than certain value,but the one of weighted average nearest neighbors degree is nearly zero on the bus network,the railway network and the combined one.To the airplane network.,the correlation of unweighted and weighted average nearest neighbors degree is disassortative.The relation of the clustering coefficient and degree denote C(k)～k^-1,but the weighted clustering coefficient doesn't change to all degree value on the bus network,the railway network and the combined one.The relationship between the unweighted or weighted clustering coefficient and degree shows C(k)～k^-1 or C_H^w(k)～k^-1.Some results are not same with other regions.This is decided by the scale and characteristic of Chinese city passenger transportation network.