Federal investigators say the Maryland Transportation Authority failed to complete a recommended vulnerability assessment that would have shown the Francis Scott Key Bridge was at significant risk of collapse from a ship strike long before its demise last year.

The NTSB says that the Key Bridge was almost 30 times above the acceptable risk or threshold for critical bridges. Finally, the NTSB found that there are 30 owners of 68 bridges over navigable waterways that are frequented by ocean-going vessels that are likely unaware of their bridges' risk of collapse.