Research On Urban Rail Transit Network Topological Characteristics And Cascading Failure Impact From The Perspective Of Multi-layer Network

The networked development of urban rail transit leads to a serious impact on system operation when nodes,edges or lines are damaged by random attacks,deliberate attacks,equipment failures or congestion.From the perspective of network planning and design,we should correctly understand the topological characteristics of urban rail transit network(URTN),find out the important nodes,edges and lines of the network,and take necessary measures to protect such nodes,edges and lines.From the perspective of network operation,we should explore the impact of nodes,edges or lines failure in URTN,and formulate the targeted train operation schemes for different failure situations,so as to maximize the passenger travel efficiency,relieve the congestion,and avoid the waste of resources.In the previous studies on URTN topological characteristics and the effects of cascading failures,the urban rail transit system was mainly abstracted as a single-layer network by using Space L method.Such single-layer network modeling method does not fully consider the internal layout of the urban rail transit transfer station,the independence of each line,the dependence among different lines,and the heterogeneity among lines and transfer channels.Hence the research results have many deficiencies,which cannot provide effective support for relevant decision-making of urban rail transit management departments.Multi-layer networks are the research branch of complex networks.The theoretical research of multi-layer networks has been gradually improved,and its applications in the field of transportation have become more and more extensive.Therefore,the paper attempts to abstract the urban rail transit system as a multi-layer network,analyze the URTN topology characteristics and the effect of cascading failure from the perspective of the multi-layer network,and prove its rationality and effectiveness.The main work of the paper is as follows:(1)In view of the deficiency of URTN topological characteristic analysis method from the perspective of single-layer network(unless otherwise specified,URTN from the perspective of single-layer network in this paper refers to URTN constructed by using Space L method),urban rail transit system is abstracted as a multi-layer network,topological characteristic measurement indexes of the multi-layer network at the node level,edge level and network level are sorted out,topological characteristics measurement indexes of the multi-layer networks at the layer level are established,topological characteristics of URTN from the perspective of single-layer and multi-layer networks are analyzed by using relevant indicators,and the rationality and effectiveness of analyzing the topological characteristics of URTN from the perspective of multi-layer networks are demonstrated.(2)In view of the deficiency of existing URTN cascading failure model,the network modeling method,initial flow allocation rules and flow redistribution rules are improved,three cascading failure impact assessment indicators of passenger travel efficiency ratio,influence degree between lines and line passenger flow pressure are established,and a cascading failure model of URTN from the perspective of multi-layer network is proposed.(3)The cascading failure model of URTN from the perspective of single-layer network and multi-layer network are used to calculate the impacts of node,edge,and line failure in the network and the impacts of node,edge,and line failure in the network when the capacity of each side of the line changes,which demonstrates the rationality and effectiveness of analyzing the impacts of cascading failures of URTN from the perspective of multi-layer networks.Finally,according to the analysis results,urban rail transit management measures from the multi-layer network perspective for urban rail transit related departments are proposed.(4)The time complexity differences of related algorithms from the perspective of single-layer and multi-layer networks are compared.The applicability of node degree,node betweenness,node efficiency,edge betweenness,layer betweenness,inter-layer dependency,network efficiency and cascading failure simulation algorithm to large-scale URTN from the perspective of multi-layer network is analyzed.