Resilience Assessment And Enhancement Of An Urban Rail Transit Network Under Disturbances

Resilience is a comprehensive metric that reflect the system’s ability to respond to disturbances.In recent years,resilience has gradually attracted the attention of researchers,as well as constructing a resilient city has become the focus on the China’s city construction.The urban rail transit(URT)system,one of the most important infrastructures in metropolis,plays a crucial role in transporting citizens.Hence,constructing a resilient URT system is the critical content of resilient city construction in China.Nowadays,the URT system in China is shifting from system construction to its networked operation.However,various operational disturbances which lead to the system’s operation interruption occur frequently,owing to the increasing complex operation environment.It is urgent to assess and enhance the system’s resilience.Therefore,a URT network’s resilience is assessed and enhanced herein to provide suggestions for improving the system’s ability to respond to disturbances.The main research contents are summarized as follows.Firstly,the URT network’s resilience assessment theory is proposed on the basis of the introduction of the URT system’s definition and characteristic,formulation method of the URT network,and the network’s resilience.Secondly,the URT network’s attack strategies are formulated by analyzing the definition and characteristic of the network’s operational disturbances.The network’s performance is evaluated by the number of passenger trips transported by the network in unit time,which is proposed from the perspective of network’s transport capability.The network’s resilience is assessed based on the average performance loss due to the disturbances,as well as the assessment flowchart is formulated.Thirdly,the URT network’s resilience enhancement model based on formulating the optimal repair sequence is proposed by analyzing the network’s resilience enhancement problem.The model aims at maximizing the network’s resilience by taking the number of amount of the repair resource,repair teams and repair time requirements as constraints.The model is solved by NSGA-II.Finally,the proposed models are applied to assess and enhance the Chengdu subway network’s resilience under the random and deliberate disturbances to verify the models’ effectiveness.