There’s really very little that can be done to prevent this type of closure. Like partial and full closures for high winds and blizzards, falling ice closures are the result of weather that is difficult to predict or prevent. Ice usually forms during freezing rain or mixed precipitation events on the upper main and suspender cables, or on the flat surfaces of the towers, typically in the later winter/early spring months. When temperatures rise or winds pick up, that ice is knocked loose and falls to the bridge deck several hundred feet below. Because there are no anti-icing or de-icing technologies on the bridge, Authority staff generally just need to wait until the ice has stopped falling (either because it has all cleared or temperatures have dropped and it stops falling) to reopen the bridge to traffic. To further complicate matters, the weather at the tower tops is different than the weather at the road deck. It can be colder up there, keeping the ice frozen longer and causing longer closures.
Some photos and videos have been included in a video about the dangers of falling ice on the Mackinac Bridge.