A scenario model for enhancing the resilience of an urban rail transit network by adding new links

Adding new links to an existing urban rail transit (URT) network helps improve its operations by shortening passenger travel time under normal operations and disruptions. However, only a few studies have considered the impact of uncertain disruption occurrence stations on URT network design. This paper addresses this gap by proposing and solving a scenario model for determining the optimal scheme for adding new links to an existing URT network while considering the uncertainty of disruption occurrence stations. Numerical experiments are conducted on the Chengdu subway system to verify the effectiveness of the proposed model. Results indicate that disruptions occurring at a station result in an average performance loss of 0.61%. The scheme for adding new links obtained from this model helps improve network performance under normal operations and disruptions. The cumulative improved normal operating performance during the entire day and the ratio of improved weighted resilience metric are 1.638 and 24.59%, respectively. The solution of the proposed model is greatly affected by several parameters such as the total length of new links. Some useful suggestions for guiding URT network extensions are proposed based on the results of the sensitivity analysis of the above parameters.