​On May 7, 2023, about 0213 local time, the towing vessel Nickelena was transiting the Straits of Mackinac while towing deck barge BMI 209, transporting a crawler crane, when the crane boom struck the main span of the Mackinac Bridge. The contact bent the crane boom backwards, causing the boom to eventually collapse onto the aft end of the barge. There were no injuries, and no pollution was reported. Damage to the Mackinac Bridge was estimated at $145,000; damage to the crane was estimated at $665,000.

​We determined that the probable cause of the contact of the Nickelena’s towed crane on deck barge BMI 209 with the Mackinac Bridge was the captain’s and barge company managers’ ineffective voyage planning, which did not identify the crane being towed was too high to pass safely under the bridge. ​

​​Verifying Navigation Risks when Voyage Planning

For vessels and tows with high air drafts, such as crane barges, bridges pose a risk of overhead contact. Operators should ensure they have the most accurate and objective data about the crane and bridge heights before getting underway. Appropriate navigational resources such as the US Coast Pilot or navigational charts should be consulted by owners and operators when developing voyage plans to ​assess navigation risks and hazards, including the air draft relative to bridge vertical clearances along the intended route.​​​​