Safe-to-fail climate change adaptation strategies for phoenix roadways under extreme precipitation

Built infrastructure continues to become more vulnerable to failure due to shifting temperature and precipitation extremes associated with global climate change. Current infrastructure design practices require risk analysis to predict a range of weather events in which built systems endure any possible failure - or "fail-safe" design. However, if the system receives a shock that is not foreseen with the historical data, it may lead to a shutdown of the entire system and thus cause unmanageable and cascading failures. Instead, "safe-to-fail" design takes into account uncertain future threats by privileging infrastructure solutions that do not compromise the entire urban system upon failure. In this study, we link climate and urban drainage models to predict future roadway vulnerability using the EPA storm water management model (SWMM) and propose a framework for "safe-to-fail" infrastructure adaptation strategy using multi-criteria decision analysis (MCDA). We demonstrate the practicality of this framework for future flooding events in Phoenix, Arizona. Taken together, our new infrastructure design framework is important for managing future extreme weather events by taking into account "safe-to-fail" decision factors neglected in traditional "fail-safe" design.