| With the continuous growth of China’s national economy and the improvement of living standards,the mileage and passenger volume of urban rail transit have been constantly increasing.As one of the main public transportation tools,urban rail transit has become a key component of meeting residents’ travel needs due to its high efficiency,safety,and punctuality.However,with the continuous expansion and complexity of urban rail transit networks,its reliability has received widespread attention.Therefore,it is crucial to study the vulnerability of urban rail transit networks,evaluate their existing vulnerability level,identify key nodes,and implement targeted protection measures to ensure the safe operation and long-term planning of urban rail transit.This paper models urban rail transit networks using the Space L method.Based on this,vulnerability is considered from two aspects of network topology and network passenger flow characteristics,leading to the derivation of static vulnerability and dynamic vulnerability.Taking the Xi’an rail transit network as an example,network characteristics analysis and vulnerability analysis were conducted.In the study of static vulnerability,the relative value of network efficiency and the relative value of the maximum connected subgraph are used as the evaluation indicators of static vulnerability,and the random attack and deliberate attack methods are formulated to conduct attack simulation experiments on the network.In the study of dynamic vulnerability,a weighted network is established with passenger flow as the weight,passenger tolerance coefficient is introduced as an index reflecting the actual demand characteristics of passengers,and the OD passenger flow loss rate is established as a dynamic vulnerability evaluation index,and the node strength priority and node strength are formulated.Traffic betweenness priority attack strategy.Finally,the relative value of efficiency loss and OD passenger flow loss rate are used to identify key stations and intervals in static and dynamic networks,respectively.Taking node betweenness centrality,node strength,node flow betweenness,OD passenger flow loss rate and efficiency loss as indicators to comprehensively measure the importance of urban rail transit network sites,the TOPSIS algorithm weighted by the coefficient of variation method is used to establish an evaluation system for the importance of urban rail transit network stations,and the K-means algorithm is used to grade the stations.The research results show that the static network of Xi’an rail transit has scale-free network characteristics and random network characteristics.With the improvement of the network structure,the static stability of the network also increases.The network shows high robustness when facing random attacks,but exhibits obvious vulnerability when facing deliberate attacks.The dynamic vulnerability of the network during non-peak periods is lower than that during peak periods.The increase of passenger tolerance coefficient helps to reduce the dynamic vulnerability of the network and causes significant changes in the important stations in the network.The critical stations and intervals identified in static analysis are distributed in the central area of the network and the intersection of radial lines in the suburbs,while the critical stations and intervals identified in dynamic analysis are mainly located in the center of the network.The Beidajie station has the highest importance in the station importance evaluation system.Based on the research results,some feasible measures are proposed in this paper to reduce the vulnerability of urban rail transit networks.These measures include establishing a station classification management system,planning urban rail transit network lines reasonably,improving passenger tolerance coefficient,and formulating detailed and comprehensive emergency plans. |
