Resilience Enhancement of an Urban Rail Transit Network by Optimizing the Locations and Construction Sequences of New Lines: A Scenario Model Approach

The addition of new lines to an existing urban rail transit (URT) network sequentially helps improve its operation. However, only a few studies have improved URT networks by simultaneously optimizing the locations and construction sequences of new lines. To address this research gap, a scenario model for enhancing the resilience of a URT network by simultaneously optimizing the locations and construction sequences of new lines is proposed. The proposed model aims to maximize the time-saving ratio under potential disruptions and profit during the entire construction and operation periods. Numerical experiments conducted on the Chengdu subway network imply that network resilience is severely affected by disruptions and their failure severity. Station Htz and Line 7 are the most critical station and line, respectively. The proposed model can effectively enhance network resilience by simultaneously optimizing the locations and construction sequences of new lines. The manner in which parameters, such as the maximal length of new lines, affect the resilience enhancement effectiveness of the proposed model is discussed, and several useful suggestions are provided based on analysis results. In practice, the proposed model can be used to assess the ability of a URT network to respond to disruptions (e.g., equipment failures and natural disasters) and guide the extension of an existing URT network.