Research On Emergency And Vulnerability Of Urban Rail Transit Network

China's urban rail transit is in the stage of rapid development,and network operation has gradually become the norm,which plays an increasingly important role in the daily transportation of urban residents.Urban rail transit travel mode has the characteristics of dense personnel,closed space and complex organization.Ensuring operation safety is the basic condition for operation enterprises to provide urban rail transit services.Reducing the frequency and impact of urban rail transit network emergencies and improving network stability are the key areas of attention of all walks of life,especially operation managers.This paper studies the emergency and vulnerability of urban rail transit network,and provides decision-making basis for improving the stability of urban rail transit network.The main contents are as follows:Firstly,the research methods of urban rail transit network vulnerability based on complex network theory are summarized from the aspects of complex network type,statistical index characteristics,topological structure modeling,attack strategy selection and vulnerability index construction,and the research trends of key technologies are summarized.The causes,frequency,time distribution,time distribution,time length distribution,influence scope and other temporal and spatial characteristics of Beijing urban rail transit network from 2013 to 2018 are analyzed.It lays a foundation for the design of simulation attack strategy based on the frequency and characteristics of emergencies and the vulnerability index considering the factors of passenger flow and travel cost.Secondly,based on the logit function of the urban rail transit network passenger flow distribution model,the shortest path search algorithm and the effective path search algorithm are improved,the network passenger flow distribution model suitable for the local interruption of the network is established,and the algorithm is programmed with MATLAB software.On this basis,the indexes and calculation methods of network passenger flow loss rate,network effective path change rate,network average generalized travel cost and network energy efficiency are proposed.The distribution and change of section passenger flow reflect the key sections of the network;the loss rate of network passenger flow reflects the loss of passenger flow;the change rate of network average generalized travel cost reflects the change of travel cost;the change rate of network energy efficiency reflects the change of comprehensive service level of the network.Thirdly,taking the urban rail transit network of a certain period in Beijing as an example,the indexes of the network under different simulated attack experiment schemes are calculated.The results show that the results of any single index in the loss rate of network passenger flow and the change rate of network average generalized travel cost can not reflect the vulnerability of the network,and the network energy efficiency as a comprehensive index can better reflect the change of network service level.The vulnerability ranking of the more vulnerable stations in Beijing urban rail transit network and the key sections that limit the ability of urban rail transit to cope with the emergency network are obtained.It is found that the fragility of the station is most affected by the passenger flow of the section where the station is located,whether the line is a loop line,and whether it is connected with a single point of suburban line.The key section of the network often has the characteristics of large passenger flow and low density of the location line network.