(WASHINGTON) — On May 7, 2025, a towing vessel struck a vertical lift bridge while transiting northbound on the Vermilion River in Perry, La., during rising river conditions. The investigation by the U.S. Coast Guard revealed that the vessel’s master miscalculated the bridge’s available clearance. This was due in part to relying on outdated river level data, which did not reflect rapidly changing conditions. Additionally, there were no effective means available for the master to determine the actual vertical clearance upon approach.
The investigation identified the following causal factors:
• Lack of real-time river stage data – The Vermilion River at Perry, La. (gauge station 07386980) previously provided real-time water level data used by mariners for planning safe bridge transits. However, this station was decommissioned in February 2025 due to lack of funding. Without real-time updates, the master based clearance calculations on obsolete data, contributing to the allision. This gauge station was maintained and operated by the U.S. Geological Survey and supplied real-time data to the National Oceanic and Atmospheric Administration’s National Weather Prediction Service website.
• Absence of bridge clearance gauges – The Perry Bridge, a vertical lift bridge operated by the Louisiana Department of Transportation and Development, lacked the required vertical clearance gauges that are required under Title 33 Code of Federal Regulations (CFR) Section
117.47. As a result, the master of the towing vessel had no on-scene sources available to confirm the available vertical clearance before attempting passage.
Coast Guard investigators have identified the following action for operators of bridges requiring clearance gauges:
• Ensure installation and maintenance of vertical clearance gauges at all bridges subject to 33 CFR § 117.47. Gauges should be clearly visible and calibrated to local water levels to support real-time decision-making by mariners.
Coast Guard investigators have identified the following recommended action for the U.S. Geological Survey:
• Restore or replace decommissioned real-time river gauges, particularly at critical navigational chokepoints such as bridges, locks or lift spans.
The U.S. Coast Guard issues findings of concern to disseminate information related to unsafe conditions that were identified as causal factors in a casualty and could contribute to future incidents. Findings of concern are intended to educate the public, state, or local agencies about the conditions discovered so they may address the findings with an appropriate voluntary action or highlight existing applicable company policies or state/local regulations.
For any questions or comments, contact Marine Safety Unit Lafayette (La.), Investigations Division, by email at MSULafayette@uscg.mil.
– U.S. Coast Guard
