Estimating whole-of-event consequences in interdependent infrastructure systems

Conventional risk assessments underestimate the total burden of hazards by characterizing consequences at or near the point of disruption, rather than as processes that unfold over time. This paper addresses that limitation by introducing a method to estimate whole-of-event consequences in interdependent infrastructure systems, integrating cascading failures and recovery dynamics into time-dependent risk metrics. We develop a modeling framework that generates trajectories of service disruption and restoration across electricity, water, and wastewater networks, and quantify community-level consequences using metrics such as property-days without service, outage duration thresholds, and spatial disparities in recovery. Applied to a coastal flooding case study, the results show that recovery-informed estimates differ substantially from exposure-based and static cascading approaches, revealing both greater total impacts and different spatial distributions of disruption. These findings demonstrate that a substantial portion of risk arises from the accumulation of disruption during recovery, which is not captured in conventional assessments. Whole-of-event consequences therefore provide a more appropriate basis for understanding systemic risk and for informing infrastructure investment, adaptation planning, and risk prioritization. By operationalizing consequence as a time-dependent, system-wide process, this work advances risk assessment practice and supports more accurate and equitable decision-making in interdependent infrastructure systems.