Bridge Hit By Crane After Tow Captain Relies On Faulty Estimates, NTSB Finds

The latest report released by the National Transportation Safety Board (NTSB) has revealed that the towing vessel transporting a large crane struck Michigan’s Mackinac Bridge in May 2023 after the crew failed to verify the crane’s height.

The collision caused $665,000 in damage to the crane and $145,000 to the bridge, though no injuries or pollution were reported.

The 103-foot-long towing vessel Nickelena was moving a deck barge carrying a crawler crane from Escanaba to Sault Ste. Marie, Michigan, for a construction project.

The crane had a 160-foot-long boom with an additional 5-foot rooster sheave attachment, making its total height a critical factor for safe transit under bridges.

Before departure, barge company managers estimated the crane’s boom angle to be between 50° and 60°. Using these rough calculations, they assumed the boom height was 140 feet, which they believed was safe for passing under the Mackinac Bridge.

However, the actual boom angle was 62°, making the crane’s total height 162 feet above the water. At the time of the incident, the bridge’s clearance was only 153 feet, meaning the crane was nearly 10 feet too tall to pass safely.

As the Nickelena approach…

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