ST. IGNACE, Mich. (WZMQ) – The Mackinac Bridge Authority has confirmed the bridge to sit at a lower risk of collapse due to a theoretical vessel collision under a nationally established threshold.
Following the 2024 collapse of the Francis Scott Key Bridge in Baltimore after it was struck by an ocean-bound container ship, the National Transportation Safety Board (NTSB) called on the evaluation of 68 bridges nationwide, including the Mighty Mac. Owners were issued to calculate the annual frequency of collapse for their bridges using the American Association of State Highway and Transportation Officials (AASHTO) Guide Specifications and Commentary for Vessel Collision Design of Highway Bridges.
After the full-scale evaluation, from its base structure to frequency of passing vessels, the report shows two probability results far under a 1% rate of collapse.
To be exact, in a press release the MBA states “the report found a total annual frequency of collapse of 0.000097, corresponding to a return period of approximately 10,350 years, which is below the AASHTO limit of 0.0001 for critical bridges. For one-way vessel traffic, the calculated annual frequency was 0.000045.“
“It confirms what we suspected all along,” said Bridge Director, Kim Nowack. “We hope it gives some reassurance to our patrons that they don’t have to worry about those kinds of things happening at the Mackinac Brige.”
In comparison, the Francis Scott Key Bridge was found to be almost 30 times above the acceptable risk threshold at the time of its collapse.
