Operationalizing resilience for sustainable infrastructure governance across the life cycle

Abstract Sustainability and resilience expectations for infrastructure are escalating faster than the regulatory frameworks meant to deliver them. This mismatch is most acute for ageing critical infrastructure. Yet, adaptation decisions remain fragmented because resilience and sustainability operate on fundamentally different temporal domains: resilience captures short-term recovery dynamics and service continuity. Instead, sustainability evaluates long-term impacts across their life cycle. Here, we depart from this temporally disjoined approach. Instead of analysing trade-offs between resilience and sustainability metrics separately, we introduce a unified decision-oriented framework that integrates short-term recovery dynamics, representing resilience, with long-term life-cycle performance, expressing sustainability, within a common optimisation structure that links these temporal dimensions. We formulate resilience as a recovery-based variable linked to retrofit implementation and integrate it with Life Cycle Assessment (LCA), Life Cycle Cost (LCC), and multi-criteria decision analysis (MCDA) to support infrastructure decision-making across the life cycle. To the best of our knowledge, existing decision frameworks have not explicitly integrated resilience and sustainability across these temporal domains within a unified optimisation framework. Applied to a landmark ageing bridge, the framework evaluates six adaptation strategies under competing resilience, cost, carbon, and longevity objectives. Our results show that system level transformation with limited structural intervention can outperform conventional strategies, achieving stronger tradeoffs across resilience, environmental impact, cost, and service life extension. These findings provide actionable evidence for extending the lifespan of ageing infrastructure, while reducing environmental footprints. Thus, they offer a scalable pathway for aligning infrastructure adaptation with sustainability and resilience objectives under real-world constraints.