Vulnerability Assessment of Infrastructure Networks Following Earthquakes: The Fundamental Step to Assess Network Resilience and Functional Recovery

Abstract

Disruptive events can result in devastating damage and interruptions in distributed infrastructure networks (e.g., Transportation network), affecting the lives and wellbeing of communities that rely on their functionality. The massive monetary recovery costsﾗin addition to the social tollﾗare alarming due to the increase in both the frequency of disruptive events and in the population, density exposed to these events. The recovery process may take a considerable amount of time. Lengthy recovery processes alone, pose multiple challenges in providing basic services to communities, such as lack of access to jobs and schools. Thus, there is a need for infrastructure networks to restore their functionality or return to service more quickly following a disruptive event. This is where the concept of functional recovery emerges. Functional recovery is a performance state in which the basic services of the system/network are restored within an acceptable timeframe, thereby enabling the continuation of key community functions that depend on their services.

Thus, there is a need to implement functional recovery concept in the design and planning stages of infrastructure networks with appropriate metrics as a basis to increase infrastructure network resilience and decrease the functional recovery time, therefore, reducing long-term effects on community.

A part of an ongoing NIST research initiative, this project aims to develop a robust computational framework to enhance the resilience of infrastructure networks when they are subjected to seismic hazard and minimize their post-earthquake recovery time. The framework will be used to assess network performance and ensure the network is able to regain acceptable levels of functionality, maintain integrity and stability, and restore services within an acceptable timeframe. To do so, different methods of scenario, and probabilistic regional hazard analysis, integrated with complex network theory (CNT), are employed to model, and analyze the recovery of such networks after earthquakes.

This project identifies the most vulnerable components of the network to support targeted design and mitigation strategies for enhancing the resilience and reduce the functional recovery time. To illustrate the application of this framework, this study presents the seismic functional recovery assessment of the San Francisco BART light rail transportation network. The outcomes of the assessment are used to help inform the area of the vulnerability within the network, develop metric to quantify its overall system resilience, and determine the time that is required to restore the network to the certain target of functionality following disruption.