NTSB found Key Bridge exceedingly vulnerable before collapse
The Francis Scott Key Bridge was nearly 30 times above the American Association of State Highway and Transportation Officials’ acceptable risk threshold when it was struck by a vessel and collapsed in March 2024.
The National Transportation Safety Board revealed this assessment on Thursday, March 20 as it continued its investigation into the Key Bridge collapse. The NTSB found that the risk of collapse could have been proactively reduced if the Maryland Transportation Authority had conducted a vulnerability assessment based on recent vessel traffic.
Guidelines for new bridges were developed by AASHTO in 1991 following the collapse of the Sunshine Sky Bridge in Florida. Since 1994, the Federal Highway Administration has required new bridges be designed to minimize the risk of catastrophic bridge collapse. The Key Bridge was built before FHWA required vulnerability assessments.
Outside of the Key Bridge findings, NTSB is also recommending 68 bridges in 19 states, including the Sunshine Sky Bridge, conduct assessments to determine the risk of bridge collapse from a vessel collision.
Today, the NTSB issued four urgent safety recommendations to select bridge owners, the Federal Highway Administration (FHWA), the US Coast Guard, and the US Army Corps of Engineers to safeguard bridges from vessel strikes. Read the interim report: https://t.co/eFlrP2gkR9 pic.twitter.com/N5oFala38t
— NTSB (@NTSB) March 20, 2025
The FHWA, U.S. Coast Guard and U.S. Army Corps of Engineers are being advised by the NTSB to establish a team to provide guidance and assistance to bridge owners on evaluating and reducing risk.
The Coalition Against Bigger Trucks recently released its study on the structural and financial ramifications on bridges due to any increase in maximum truck weights.
Currently, truck weight limits are set at 80,000 pounds, but an increase to 91,000 pounds has been proposed in Congress.
“These at-risk bridges represent a sizable portion of the nation’s bridge infrastructure, located on local roads and highways that are critical for everyday transportation and commerce,” the Coalition’s study said.
More than 80,000 bridges with a potential replacement cost of over $98 billion fall within that at-risk category, according to the Coalition Against Bigger Trucks, which includes OOIDA.
Read the full NTSB report online or the Coalition Against Bigger Trucks’ study here. LL
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