The Vulnerability Analysis Of Urban Complementary Transit Network Under Spatially Localized Failures

With the development of social economy and the continuous progress of urbanization,urban public transportation,especially urban rail transit system,has become the first choice to solve traffic congestion problems in many cities.In densely populated cities,urban rail transit system carries a large number of urban residents' travel tasks and plays a critical role in the public transport system.However,equipment failures,traffic accidents,extreme weather,natural disasters and other sudden events may lead to the operation and safety problems of urban rail traffic system,which may seriously affect people's travel efficiency and personal safety.Therefore,how to analyze the performance response of the public transportation system in the case of disruptions,find out the critical stations or attack sites and design the protection strategies,become more and more important in recent years.At present,most of the related research studied the vulnerability of a single transportation system,such as bus system or subway system,and the disaster modes are mainly intentional attacks based on network topology.Few studies consider the geographical location relationship between the damaged sites,such as the disruptions caused by natural disasters and bomb attacks.This paper proposes an analysis framework for analyzing the vulnerability of the complementary traffic system(composed of subway and road system)under spatially localized failures.The urban rail transit system and road system in Wuhan is used as an example to verify the availability and effectiveness of the framework.First,this paper introduces the definition of railway system vulnerability and spatially localized failures.Two types of spatially localized failures models,Node-Centered Spatially localized failures(NCSLFs)and Circle-Shaped Spatially localized failures(CSSLFs),are considered.The method to identify the key areas of urban rail transit is discussed.Second,taking Wuhan rail transit system as an example,the system vulnerability is analyzed under four kinds of attack strategies(random failures,random NCSLFs,degreesfirst CSSLFs and nodes-first CSSLFs),and three kinds of performance indicators(average degrees,largest component size and accessibility)are adopted.The results show that urban rail transit is more vulnerable under random failures than under random NCSLFs,while the degrees-first CSSLFs causes greater damage to the system than the nodes-first CSSLFs.Finally,the vulnerability of complementarity transportation system in Wuhan under spatially localized failures is analyzed.The results show that the vulnerability of Urban rail transit system under the consideration of complementary relationship will be significantly reduced.