Infrastructure Resilience Curves: Performance Measures and Summary Metrics

Resilience curves communicate system behavior and resilience properties to critical infrastructure stakeholders and can quantitatively facilitate resilient design. Generally, these curves illustrate the evolution of system performance before, during, and after a disruption. As simple as these curves may appear, the literature contains underexplored nuance when defining "performance" and distilling curves with summary metrics. This manuscript, through a review of 274 publications, defines a taxonomy of resilience curve performance measures and discusses associated performance targets and normalization techniques. Furthermore, a taxonomy of summary metrics is defined to facilitate comparisons of system behavior and resilience strategies. In addition to defining common taxonomies, this review synthesizes recommendations for selecting measures and metrics for common applications and stakeholders across critical infrastructure resilience domains. Key recommendations include broader adoption of productivity measures with variable and adaptive performance targets; deliberate consideration of curve milestones when defining summary metrics; and the need for future research on variable and adaptive weighting for ensemble measures and metrics.