Research On Urban Rail Transit Network Vulnerability Based On Complex Network Theory

In recent years,urban rail transit has become an important development direction to solve the problem of urban congestion in China with its advantages of high transportation efficiency,safety and environmental protection.However,with its rapid development,the security operation is also facing new challenges.In order to ensure the safe operation of the existing urban rail transit and the scientific planning of the long-term urban rail transit network,managers and planners must understand the vulnerability level of the existing network to find ways to reduce the vulnerability of the network.In this paper,the vulnerability of urban rail transit network is divided into static vulnerability and dynamic vulnerability from two aspects of network physical structure and operation state.The complex network theory provides a new methodology for the study of urban rail transit network vulnerability.This paper studies the static and dynamic vulnerability of urban rail transit network as a complex network.For the research of static vulnerability,the Space L method is used as the network model construction method,and the relative values of network efficiency and the relative value of the largest connected subgraph are selected as the evaluation indexes of static vulnerability of urban rail transit network.On this basis,the simulation system of two network attack strategies,random attack and intentional attack,is designed.For the study of dynamic vulnerability,based on the concept of “degree” and“betweenness” in the complex network theory,this paper introduces “node flow degree”,“node flow betweenness” and “side flow betweenness” to construct the dynamic vulnerability identification index of network unit,and proposes the failure of network unit impact assessment indicators,which is used to test the accuracy of the dynamic vulnerability identification index.On this basis,a dynamic vulnerability assessment and verification model based on Visum macro traffic analysis software is constructed,and a reasonable solution to the key problems in the model is given.Finally,taking Shanghai subway network as an example,the static and dynamicvulnerability assessment is carried out.In the static vulnerability assessment,firstly,based on the commonly used complex network statistical indicators,the complex topological characteristics of the network are analyzed and the conclusion is drawn: Shanghai Metro network is a scale-free network as well as a small world network.Secondly,the failure simulation experiment of Shanghai Metro network shows that: vulnerability under node degree first attack > vulnerability under node betweenness first attack > vulnerability under random attack.Finally,based on the loss value of network efficiency,the key stations and key sections in the network are identified after the failure simulation of single node and edge.In the dynamic vulnerability assessment,after the traffic distribution of Shanghai Metro network,the dynamic vulnerability identification index of network unit is calculated,and then the network unit failure impact evaluation index is calculated by the network unit failure simulation experiment in the way of sampling,and the accuracy and effectiveness of the dynamic vulnerability identification index are verified.Based on the realization of the above two static and dynamic vulnerability assessment models,this paper compares the static and dynamic vulnerability analysis results of Shanghai Metro network and puts forward suggestions to reduce the network vulnerability.