Bridge owners across the United States continue evaluating critical infrastructure following federal recommendations issued after the 2024 collapse of the Francis Scott Key Bridge in Baltimore. A new engineering assessment has concluded that Michigan's Mackinac Bridge meets national reliability criteria for vessel collision risk established by the American Association of State Highway and Transportation Officials (AASHTO).
The Mackinac Bridge Authority retained engineering consultant Parsons to perform the analysis using AASHTO's Guide Specifications and Commentary for Vessel Collision Design of Highway Bridges.
The study evaluated the bridge's structural characteristics, the navigational environment within the Straits of Mackinac and the size, frequency and types of vessels operating near the crossing.
The assessment determined the bridge's calculated annual probability of collapse from a vessel collision is below AASHTO's acceptable threshold for critical highway bridges.
The evaluation was conducted after the National Transportation Safety Board requested vessel collision vulnerability assessments for 68 bridges in 19 states following the collapse of the Francis Scott Key Bridge in March 2024.
The analysis submitted by the Mackinac Bridge Authority concluded that the bridge satisfies the reliability criteria established under current AASHTO guidance for critical infrastructure.
The federal review highlights the increasing emphasis on risk-based infrastructure management for major bridges located along commercial navigation routes. Engineering assessments of vessel collision risk help transportation agencies prioritize long-term maintenance, resilience planning and capital investments.
For bridge owners, engineers and contractors, these evaluations support informed decision-making regarding structural upgrades, protective measures and lifecycle management of critical transportation assets.
Source: Michigan Govt.
