Each winter, ice forms on the cables and towers of the Mackinac Bridge, usually from freezing rain. When winds increase or temperatures rise, that ice can dislodge suddenly, sending sheets or spears of ice cascading down to the bridge deck below.
“Ice falling from the bridge towers and cables can fall more than 300 feet before hitting the bridge deck, and the pieces are sometimes large enough to damage vehicles, and definitely large enough to cause injuries,” said Mackinac Bridge Authority Executive Secretary Bob Sweeney. “While it’s inconvenient to close the bridge at any time, the safety of our customers is too important to risk.”
During a few closures, Mackinac Bridge Authority pickups have been struck by falling ice. The employees driving them were unhurt, but the vehicles were heavily damaged.
When the bridge is closed due to falling ice, it’s a guessing game as to when it can be reopened. During the longest falling ice closure – 15 hours and 45 minutes on April 11 and 12, 2017 – temperatures hovered around freezing and new ice was forming on the bridge as soon as other ice broke free. The shortest closure was 37 minutes on Nov. 29, 2001. The bridge has closed 16 times for falling ice since 1995.