That is the recommendation of the National Transportation Safety Board (NTSB), amid an ongoing investigation into the collapse of the Francis Scott Key Bridge in Baltimore.

The NTSB found that the Key Bridge, which collapsed after being struck by the container ship Dali on 26 March last year (2024), was almost 30 times above the acceptable risk threshold for critical or essential bridges.

That was measured according to guidance established by the American Association of State Highway and Transportation Officials (AASHTO).

The NTSB has identified a further 68 bridges that were designed before the AASHTO guidance was established 鈥� like the Key Bridge 鈥� that do not have a current vulnerability assessment.

It called on the 30 owners of those 68 structures to calculate the annual frequency of collapse for their bridges using AASHTO鈥檚 Method II calculation.

However, it stressed that its findings do not mean that the 68 bridges are certain to collapse.

The NTSB recommended that bridge owners develop and implement a comprehensive risk reduction plan, if the calculations indicate a bridge has a risk level above the AASHTO threshold.

The NTSB is also recommending the Federal Highways Administration (FHWA), the US Coast Guard and the US Army Corps of Engineers establish an interdisciplinary team to provide guidance and assistance to bridge owners on evaluating and reducing the risk, which could mean infrastructure improvements or operational changes.

Six construction workers died and another was injured, as well as one person onboard the Dali, when the vessel experienced a loss of power and struck the southern pier supporting the central truss spans of the Francis Scott Key Bridge, which subsequently collapsed.