Michigan Department of Transportation photo Above, a chunk of ice more than an inch thick that fell on the Mackinac Bridge recently is held by workers. The Mackinac Bridge was closed due to hazardous ice conditions Wednesday, marking the third closure in as many days. No timetable was given for when the bridge might reopen.

ST. IGNACE — Due to falling ice from cables and towers, the Mackinac Bridge was closed again Wednesday while officials waited for safe conditions.

While the bridge did re-open Thursday morning as announced, as of Thursday afternoon the Mackinac Bridge Authority reported winds of sufficient force (35 – 49 mph) in the Straits area to require an escort of certain ‘high profile’ vehicles across the Mackinac Bridge.

Examples of high profile vehicles include pickup trucks with campers; cars with small boats, bicycles or luggage attached to the roof; Ryder or U-Haul trucks; any vehicle pulling a boat; semi-tractors with enclosed trailers and all trailers with side walls over two feet in height. High profile vehicles must be escorted.

Motorists are asked to reduce their speed to 20 miles per hour as they approach the bridge and be prepared to stop. Bridge personnel are stationed at both ends of the structure to provide instructions regarding how and when to proceed across the bridge.

According to a release from the Mackinaw Bridge Authority issued Wednesday, maintenance staff at the bridge said the amount of ice that formed as a result of last week’s storm was “unprecedented” and “the size of ice sheets, spears and chunks that are falling are dangerous to anyone out on the bridge deck.”

Ice falling from the bridge from flat surfaces may be as large as garage doors and spears and other chunks may fall hundreds of feet. In the past, some pieces that have survived the fall have been as large as a loaf of bread and have caved in windshields and roofs on both authority and private vehicles.

The closures have also resulted in fuel shortages in the Sault Ste. Marie, Mich. area, as trucks carrying regular fuel deliveries have been unable to cross the bridge. Some Sault-area gas stations ran out of fuel completely Tuesday.

Authorities are monitoring the situation closely and will provide updates as fuel supplies stabilize. Residents are encouraged to temporarily conserve fuel where possible and avoid unnecessary travel until the local fuel supplies are replenished.

To receive notice of the bridge’s reopening, motorists may text “MacBridge” to 67283.