Research On Topological Properties And Lines Connectivity Of Public Transport Network Based On Complex Network

With the rapid growth of the urban vehicles population of China, the phenomenon of traffic congestion has become increasingly serious in major cities. Urban public transport, as an effectively method that can reduce the pressure on urban traffic, has been widely recognized at home and abroad, and got a wide research and quick development. In general, urban public transport network consists of a large number of routes and stations, and there have certain relationships between routes and stations, routes and routes, stations and stations, which accord with the characteristics of complex system. Based on the complex network theory, the actual urban public transport network can be abstracted, and then the actual problems can be easily researched and analyzed by means of mathematics.The paper, using the complex network theory, researched and analyzed the topological properties of public transport network, and the connectivity and optimization strategy of bus routes. The paper mainly includes the following two parts:(1) The directed-weighted network on space-of-stations was built based on the theory of complex networks. The differences between upline and downline (inner ring and outer ring for circle line) on bus station arrangement and driving directions are considered. The results show that the average node degree of the network in space-of-stations in Chengdu is 2.52, the node strength, with the maximum at 45 and average at 4.75, performs an uneven distribution. The network follows the power-law distribution as a whole and has obvious small world property. With the expansion of the network size from urban area to suburbs, the average shortest path length of the network increases obviously from 16.90 to 34.19. The clustering coefficient is 0.14, which reflects the high standard of the public traffic net relatively.(2) The public traffic network on space-of-routes was built based on the theory of complex networks. The paper sequenced the network nodes by node degrees to evaluate the connectedness of sub-nets formed by the top a node degrees, and furtherly, sorted the bus lines by line properties to analysis the connection properties between different sorts. The results show that the clustering coefficient of the whole network is 0.566 and the sub-net, formed by the nodes with top 10 percent node degrees, is 0.721, which demonstrates the obvious "Rich Club" Phenomenon. BRT and rail transit routes are the core lines for transport transfer. Urban lines formed the main part of the public transport, but they reduced the connectedness of the network at some level. Feeder bus lines and suburban lines play important roles in keeping the connectedness steady. Community bus lines majorly connect main lines and enhance the connectedness at some level.