Criticality, resilience and prioritization of components in interdependent infrastructure systems: An overview of definitions and quantitative modelling approaches

Enhancing the resilience of critical infrastructure (CI) systems has become a focal point of national and international policies. However, the formulation of resilience enhancement strategies often requires component- (i.e. asset-) level prioritization, which entails many complexities. Acknowledging the complex and interdependent nature of infrastructure systems, this paper aims to aid researchers, practitioners and policy-makers by presenting a review of the relative literature and current state-of-the-art, and by identifying future research opportunities to improve the applicability and operationalizability of CI component identification and prioritization methods. Theoretical and practical applications are reviewed for definitions, analysis and modelling approaches regarding the resilience of interdependent infrastructure systems. A detailed review of infrastructure criticality definitions, component criticality assessment and prioritization frameworks, from scientific, policy and other documents, is presented. A discussion on social justice and equity dimensions therein is included, which have the potential to greatly influence decisions and should always be incorporated in infrastructure planning and investment discussions. The findings of this review are discussed in terms of applicability and operationalizability. Key recommendations for future research include: (i) developing quantification frameworks for CI component criticality based on formal definitions and multiple criteria, (ii) incorporating the entire resilience cycle of CI in component prioritization, (iii) accounting for the socio-technical nature of CI systems by integrating social dimensions and their wider operating environment and (iv) developing comprehensive model validation, calibration and uncertainty analysis frameworks.