Analysis On Network Characteristics Of Multi-dimensional Urban Rail Transit Under Network Operation Condition

In response to the development strategy of “Rail Transit + New-type Urbanization”proposed by the national “13th Five-Year Plan”,many medium-sized and small cities have approved the construction of Urban Rail Transit network represented by subway and light rail in China,it has gradually formed a status of multiple modes of rail transit.Based on this,the concept of Multi-dimensional is first proposed in this paper,and take the Urban Multi-dimensional Rail Transit network(hereinafter using abbreviation MRT)as research objects.Tianjin urban MRT network characteristics and its evolution are studied using the theory of complex network.Then some measures to enhance the topological properties are proposed,so as to provide reference for MRT network optimization operation and planning.The main contents of this paper are as follows:(1)This paper gives the definition of the urban MRT.The network samples were established based on the data of Tianjin MRT network in 2017,the topology of MRT network was modeled by using space L and space P methods respectively.And then the static characteristics of the MRT topology model are analyzed with Ucinet software,including the degree distribution,the critical path length,the clustering coefficient and the betweenness.The results showed that the MRT network have obvious scale-free properties and small-world effects in the L space model and have the small world effects and the exponential distribution properties in the P space model.Meanwhile,it also draws a conclusion that L space model is more suitable for researching the complex structure and evolution properties of MRT network.(2)The dynamic changes of MRT network under the condition of random attacks and targeted attacks are studied by establishing the evaluation index of connectivity,functionality and repairability in this paper.At the same time,the key stations of the MRT network are located.Using Matlab software to simulate the deletion process of nodes under different strategies.Through the analysis of the evaluation index of connectivity and functionality,it is found that the targeted attacks was far more destructive on topological structure than the random attacks.The strategy of sort by degree of update nodes has the greatest destruction to the MRT network topology.The strategy of sort by degree of nodes and sort by betweenness have shown a period of weakness in the destruction of the MRT network topology when the attacked nodes reaches a certain amount.Through the analysis of the evaluation index of repairability,it is found that the strategy of sort by degree of nodes is obviously superior to other strategies in a certain range.When it beyond the critical point of the repairability index shown emergent phenomena.(3)Through statistic analysis of the basic network sample of Tianjin MRT network in different stages of development(including the basic network,the skeleton network,the transition network and the stabilization network)since operation,the variation characteristics of the static parameters of the MRT network are studied at different stages.The results showed that the index of average degree of nodes and critical path length in the network is increased obviously when the MRT network evolves to the stage of stabilization network.Meanwhile,the network efficiency has declined because of the increase of MRT network coverage at this stage.The evolution characteristics of topological structure are analyzed in the view of attacking the station or line,it found that there has little influence on the stage of stabilization network when a single station or single line was attacked.The importance of a part of stations and lines have changing with the evolution of MRT network.