A New Failure Strategy to Enhance the Vulnerability Assessment of Urban Metro Networks

Urban Metro Networks (UMNs), as an integral component of transit systems, play a crucial role in the overall efficiency of urban transportation. Disruptions in their operations can significantly impact daily travel. Consequently, numerous studies have focused on assessing the vulnerability of UMNs. However, many of these studies have not adequately considered the infrastructural characteristics of UMNs. This study seeks to emphasize the importance of incorporating infrastructural features—particularly Stations with Direction-Change Facilities (SDCFs)—to enhance the accuracy of research findings. To address this, we introduce the Block-Based Failure Strategy (BBFS), a novel approach that accounts for SDCFs. The Montreal UMN is selected as the case study, and its vulnerability to targeted disruptions is assessed using both BBFS and a conventional strategy known as the Node-Based Failure Strategy (NBFS). The results reveal a significant disparity between simulations conducted using BBFS and NBFS. When SDCFs are considered and BBFS is applied, the network is deemed fully degraded after 9 targeted disruptions. In contrast, the NBFS simulation suggests that the network can withstand up to 35 targeted disruptions before becoming completely degraded—a figure much higher than what would realistically occur.