For the third time in as many days, the Mackinac Bridge is temporarily closed to all traffic because of ice falling from the bridge structure onto the freeway lanes. 

While this scenario has happened occasionally in the past, the Mackinac Bridge Authority said this week's disruptions are unprecedented with ice building up several inches thick in some spots. Bridge closings were ordered on Monday, again on Tuesday and could continue for some time yet. Some of the ice that has fallen caused noticeable damage to both bridge authority and privately owned vehicles. 

It's just one of the impacts of an ice storm that began Saturday in Northern Michigan and derailed travel, electricity and communications throughout the region. 

The suspension bridge along I-75 is the only road connection between the two peninsulas of the state. The tower tops are more than 300 feet above the roadway.  

A typical closure for falling ice lasts about five hours, the bridge authority said. Monday's closing lasted for three hours. Tuesday's closing lasted for 10 ½ hours. Wednesday's closing started at 2:30 a.m.; and as of 1 p.m., travel was still shut down. 

"Unlike high wind closures where weather forecasts can give us solid information on when winds are expected to diminish, guessing when ice will fall and stop falling is just a guess," Mackinac Bridge Director Kim Nowack said in her report. "For the safety of all involved, we need to keep our system simple: when ice is falling from the towers and cables, we close the bridge until it stops." 

Nowack also said local emergency and relief services are stretched thin in their efforts to deal with the circumstances for residents and others who were up north when the storm hit. 

"We discourage travelers from coming here expecting to cross the bridge. Please don't travel here if it's not absolutely necessary," she said. 

Those who want to keep up with notifications can sign up for text alerts from the bridge authority.