Assessing Survivability of the Beijing Subway System

Abstract

The Beijing subway system, the third largest in the world, serves more than ten million passengers a day. As Beijing is the capital city of China and thus a booming urban center, its subway system has experienced rapid evolution from a local single line system to a complicated network. Due to its constantly increasing complexity, the system is both a critical asset for a local transit artery and a bridge between intercity transportation modes, increasing the issue of network survivability in the face of potential outages of network components. In this study, we provide a connectivity-based survivability measure with which to explore how potential outages of network components might affect the overall functionality of the Beijing subway system. System survivability is measured from two perspectives: [1] topological connectivity under various simulated failures of transfer stations and [2] variations in passenger flow in response to disruptive factors. Plausible scenarios are constructed using local demographic data and daily shipment reports from subway management companies. To assess the possible range of influences, we develop a weighted rank-based simulation algorithm to approximate exact solutions to extreme combinatorial outage instances. The range of potential effects highlights the best and worst-case scenarios to identify critical components and help to prepare corresponding contingency plans. This research will enable planners in urban environments, where infrastructure functionality, particularly that of public transit systems, is critical for maintaining socioeconomic security in times of crisis.