There's no such thing as free shipping: The significant risk large vessels pose to U.S. bridges

Abstract

The collapse of the Francis Scott Key Bridge in Baltimore, Maryland in March 2024 raised major concerns surrounding bridge safety in the United States. This work presents the first comprehensive, data-driven investigation of large-vessel allision1 risk for all major bridges in the United States and shows that the risk of a ship strike is high for 54 bridges. The study follows the American Association of State Highway and Transportation Officials Method II vulnerability assessment approach and is based on detailed large vessel traffic analysis for 357 bridges across the United States. Each bridge was identified from the National Bridge Inventory by screening all 624,170 bridges in the database and performing an initial traffic assessment of 4,464 bridges using Automatic Identification System (AIS) ship-tracking data. The study further shows that the aggregated risk of vessel allision across the full portfolio of bridges in the United States is very high, with an allision event expected once every 2.3 years – a trend that is unfortunately consistent with historical records. Importantly, the study only assesses allision risk and does not investigate the probability of collapse for individual bridges, which would require detailed structural analysis. These conclusions motivate the need for detailed collapse risk assessments for numerous bridges across the United States and investment in appropriate protective measures where necessary.