Assessing highway bridge scour reliability and risk under changing floods

Hydraulic events threaten highway bridge safety as more than 55% of bridge failures in the United States (U.S.) are attributed to floods. It is now well-documented that climate change could cause an increase in extreme precipitation leading to larger and more frequent floods in many U.S. regions. This study presents a systematic framework for the reliability analysis of bridges under future changing flood conditions. The bridge scour safety assessment process is demonstrated using a case study representing bridges over Schoharie Creek in Upstate New York, with more than 100 years of peak flow data and evidence of an increasing trend. Our results show that this trend could cause about an 18% increase in the probability of scour failure over the 75-year service life of bridges designed using current procedures. The reliability index for foundation scour should ideally surpass β = 2.5 to effectively lower the risk to acceptable levels.