Resilience Assessment of an Urban Metro Complex Network: A Case Study of the Zhengzhou Metro

Abstract

An urban metro network is susceptible to becoming vulnerable and difficult to recover quickly in the face of an unexpected attack on account of the system’s complexity and the threat of various emergencies. Therefore, it is necessary to assess the resilience of urban metro networks. However, the research on resilience assessment of urban metro networks is still in the development stage, and it is better to conduct said research using a technique which combines many attributes, multiple methods, and several cases. Therefore, based on the complex network modeling and topological characteristics analysis of metro systems, a metro network’s robustness and vulnerability measurement method under node interruption and edge failure is proposed for the first time in this study. Then, considering the three cases of general station interruption, interchange station interruption, and traffic tunnel failure, a quantitative resilience assessment model of metro networks is put forward, and the corresponding recovery strategies are discussed. Finally, a case study of the Zhengzhou Metro Network (ZZMN) under an extreme rainstorm is conducted to demonstrate the viability of the proposed model. The results show that ZZMN possesses scale-free and small-world network properties, and it is robust to random interruptions but vulnerable to deliberate attacks. ZZMN still needs to improve its effectiveness in information transmission. The centrality distribution for each node in the ZZMN network differs significantly, and each node’s failure has a unique impact on the network. The larger the DC, BC, and PR of a node is, the lower the network’s robustness after its removal is, and the stronger the vulnerability is. Compared with the three cases of general station interruption, interchange station interruption, and traffic tunnel failure, the network loss caused by tunnel failure was the lowest, followed by general station interruption, and the interruption at interchange stations was the most costly. Given the failures under various cases, the metro management department should prioritize selecting the optimal recovery strategy to improve the resilience of the metro network system. This study’s findings can assist in making urban metro systems less vulnerable to emergencies and more resilient for a quick recovery, which can provide scientific theoretical guidance and decision support for the safety and resilient, sustainable development of urban metro systems.

State-of-the-Art Review of the Resilience of Urban Bridge Networks

“…In 1973, Holling first applied resilience in the field of systems ecology to characterize the ability of ecosystems to remain stable [24]. Since then, resilience has been widely used in research in various fields, such as construction [25], transportation [26,27], medical treatment [28], water supply [29], electricity supply [30] and gas supply [31].…”

Dynamic Influence Analysis of the Important Station Evolution on the Resilience of Complex Metro Network

“…Moreover, EC (Eigenvector Centrality) [39] considers the importance of a node's neighbors, while PR (PageRank) [41] calculates the order of nodes according to the structure of the incoming link. The above common calculations of node centrality are implemented according to the methods in previous studies [12,19].…”

“…When the urban metro network is confronted with unexpected or deliberate disturbance, the vulnerability [16][17][18] of the system will be increased. To reduce this vulnerability, the metro network system needs to possess a strong recovery capability, i.e., resilience [19][20][21]. Resilience is the capacity of a system to absorb, resist, and quickly recover from external risks.…”

“…Zhang et al [32] studied the characteristics (vulnerability, robustness, rapidity, and degree to return) of the metro system's responses to the disturbance with a multivariate multiple regression model and quantitatively evaluated COVID-19-caused resilience performance of metro rails using the metro transit data from the United States. By taking into account general station interruption, interchange station interruption, and traffic tunnel failure, Qi et al [19] proposed a quantitative resilience assessment model of metro networks and examined the corresponding recovery strategies. Considering three dimensions of resistance, recovery, and adaptation and combined with ordered binary comparison, entropy weight, and cloud model, Jiao et al [33] developed a model for evaluating metro stations' resilience levels against rainstorm disasters and used Chongqing metro system as a case study.…”

Impact of extreme rainfall on metro network resilience: Shanghai metro as an example

“…Lu developed an importance-impedance-based rail transit network resilience approach, which comprehensively considered topological and passenger flow characteristics [3]. Qi et al proposed a model to assess resilience quantitatively while considering three interruption cases: general station, interchange station, and traffic tunnel [4]. However, these study have not considered specific disaster conditions, and the simple assumptions of attack mode (i.e., random attack and intentional attack) are not practical.…”