Elizabeth Carter, Marilyn Smith

Over 30,000 hazardous material pipeline (HMP) failures have been reported in the US since 1970, associated with 274 fatalities, 1,120 injuries, and nearly $11 billion in damages. Tropical cyclones are under-recognized as drivers of pipeline failures, mainly because failures aren't associated with tropical cyclones on operator-generated incidence reports, limiting analysis. This study defines tropical cyclone-associated pipeline failure frequency using a conservative framework based on spatiotemporal concomitance with the tropical cyclone storm tracks. A modeling framework that accounts for unparameterized spatial and temporal non-independence in HMP failure frequency, as well as collinearity in meteorological metrics of tropical cyclone intensity, is used to evaluate spatiotemporal variability in local HMP failure frequency associated with variable tropical cyclone intensity. Over 70% of reported pipeline failures in tropical cyclone-active regions occur within the first year of a tropical cyclone exposure. Since 1975, the annual frequency of tropical cyclone-associated pipeline failures has increased by an order of magnitude. Storm intensity (minimum pressure and maximum wind speed) is significantly related to the number of pipeline failures associated with a storm, explaining 24% of spatial variability and 34% of inter-annual variability in local storm-level pipeline failure frequency. Pipeline systems in the Texas Gulf Coast, Mississippi Delta Region, Northeast, and High Plains regions are most susceptible to tropical cyclone-associated failures. Assuming linear continuations of meteorological trends observed in 1970-2020, our results suggest that we may see a 50-600% increase in the number of pipeline failures occurring during the local annual average maximum tropical cyclone by 2050. Implications of accurate natural hazards-related cause attribution on HMP failure incident reports are discussed.