2017-04-20 / Front Page

Falling Ice Closes Bridge Overnight

By Erich T. Doerr

Persistent falling ice cut off the route between Michigan’s peninsulas Tuesday, April 11, and Wednesday, April 12, as weather caused an extended closure of the Mackinac Bridge. Ice falling from the bridge cables closed the bridge for 20 hours during a 24-hour period from Tuesday afternoon to Wednesday afternoon, stranding traffic on both sides of the bridge and forcing many to seek motel rooms for the night. A shelter was set up at Little Bear East Arena.

The 15-hour, 45-minute initial closure that stretched overnight is the longest closure the Mackinac Bridge Authority (MBA) has recorded. Bridge crews noticed ice was building up on the bridge Tuesday as a persistent freezing rainstorm moved through the area. The bridge was closed to all traffic at 2:10 p.m. when this ice began to fall. Initially, the bridge staff hoped to reopen the bridge at about 4 p.m., but it was found that the rainstorm was forming more new ice on the bridge cables just as quickly as it was falling off. Weather continued this way throughout the rest of the evening and after consulting with the weather service, it was determined the bridge would remain closed overnight, while still aiming to open the bridge as soon as possible.

By morning, the ice was frozen in place, allowing a reprieve for the bridge to reopen at 5:55 a.m. Wednesday, clearing much of the waiting traffic. As weather warmed up Wednesday morning, the remainder of the ice began to fall and the bridge was closed for a second time at 8:30 a.m. Virtually all of the ice fell off the bridge by 12:45 p.m., allowing the bridge to reopen for good.

“We try to keep the bridge open as much as possible,” MBA Executive Secretary Bob Sweeney said. “When we see an opportunity for stable conditions, even if it will only be a few hours, we’ll open to clear out the traffic as best we can.”

This was the first time the bridge was shut down for a complete overnight period, Mr. Sweeney said, although there have been prior closures that occurred during overnight hours. Local emergency managers monitored the conditions at the bridge Tuesday evening, with drivers eventually encouraged to find shelter for the night, since it was unlikely that the bridge would reopen before morning. Many sought motel rooms, and with many motels still closed for the season, some motorists on the southern end of the bridge had to drive as far as Pellston to find a room for the night. As many of the area’s hotels and motels started filling up, some people sought shelter with friends in the area, and Mr. Sweeney said he had some friends staying over at his house Tuesday night because of the closure.

The bridge closure resulted in Little Bear Arena at St. Ignace being used as an overnight shelter Tuesday for a group of about 70 middle school students and other participants in an Alpena Community College field trip to Lake Superior State University in Sault Ste. Marie. The decision to set up the shelter was made at 10:30 p.m. when Mackinac County Emergency Management was informed of the students’ situation. Emergency Management Coordinator Mike Kasper said the arena was prepared as a shelter in just 20 minutes with cots and blankets readied to give everyone a place to rest.

“Everybody worked well to make this situation as good as it could have been,” Mr. Kasper said. “We had good cooperation between law enforcement, the bridge, and everyone involved.”

The 68 eighth-grade students, four staff members, and two bus drivers who stayed overnight at Little Bear were part of Alpena Community College’s TRiO Talent Search Program, a college access program involving 16 school districts.

Program Director Bob Newton said the group initially stopped in St. Ignace for a meal break on their way back before finding the bridge was closed. He said he appreciated everyone who worked hard to help his group find a place to stay the night, including the managers at Burger King, Bryce Tracy of emergency services, and the Sault Tribal Police.

“The emergency services people were great,” Mr. Newton said. “I just want to say how grateful we are. Everyone came together to help us.”

The students spent the night at Little Bear and their two school buses were able to depart early Wednesday morning. This was the second time Little Bear East had been used as an overnight shelter for stranded travellers. The prior one occurred in 2007 when the bridge was closed during a whiteout. Emergency Management maintains a plan to use Little Bear East in emergency situations as either a shelter or a command post.

An MBA pickup truck suffered a broken windshield Wednesday morning when it was hit by falling ice while moving workers to Mackinaw City. The truck’s occupants were uninjured when a large section of ice fell on the pickup at about 10 a.m., just after the truck had driven underneath the north tower. The MBA posted a video of its truck being hit by ice at on its Web site mackinacbridge.org/close-bridgefalling ice.

Once the bridge reopened, the stream of traffic was steady. During the early morning opening, most traffic cleared the bridge in the northbound lane by 7 a.m., with the backup in the southbound lane clearing by 7:30 a.m. The midday closing also resulted in backups, with traffic clearing up in 90 minutes to two hours.

“We hope everyone understands we are here to provide safe crossings for everyone,” Mr. Sweeney said. “We appreciate everyone’s patience.”

The Mackinac Bridge’s closure records go back to the mid-1990s. Since 1995, there have been 16 closures of the bridge to account for falling ice, and four of these have occurred since December this winter.

Mr. Sweeney credited this unusual uptick to the mild winter, with warmer temperatures producing more melting conditions. There have been no changes to the bridge’s closing protocols this year. Ice only forms in the bridge in a very narrow temperature range around the freezing point of water at 32 degrees Fahrenheit, when freezing rain can occur. Colder temperatures produce snow that can lead to whiteouts, often on the bridge’s causeway, but does not build up on the bridge. Mr. Sweeney said snow rarely sticks to the bridge towers and usually blows off quickly.

“We were in that window of ice formation, more so than in a normal year,” Mr. Sweeney said.

Temperatures hovered in the 32 to 34 degrees range Tuesday, making conditions ideal for more ice to form on the bridge as soon as the previous ice fell, while rain and mist fueled its formation. Mr. Sweeney noted there was no dayto night temperature change last week, resulting in the prolonged closure; the temperature remained in the freezing range throughout the night. MBA crews tried to clear the ice from the bridge by driving several heavy sand-loaded trucks across it, looking to cause slight vibrations on its suspension portion to knock it loose. While this removed a significant amount of ice, it did not knock off enough to gain any ground during the storm, so the bridge remained closed.

Whenever the Mackinac Bridge is closed for ice, the purpose is keeping traffic safely out of the way. The falling ice poses no real danger to the bridge structure, however, it can serious damage to vehicles passing below. Some sheets up to 60 feet in length have fallen from the bridge in the past. The bridge is closed immediately after ice is noticed falling from the structure. In places, it can fall more than 300 feet from the top of the bridge before it hits the road deck. The MBA begins making preparations to close the bridge whenever ice is spotted on its cables, since it is only a matter of time before it begins to melt and falls.

When the bridge is closed, even the MBA holds off on crossing with its own vehicles unless absolutely necessary, typically only sending out its pickups to move workers and timing their crossings to maximize safety. Despite these precautions, two of its vehicles have been hit by falling ice in the past year. While the trucks were damaged, no one was hurt.

“When we do close the bridge, we do it for safety conditions, only to protect motorists from unique conditions out on the bridge,” Mr. Sweeney said.

In an average year, the bridge has just one total closure, lasting about one hour. The bridge also averages one partial closure, preventing only the 15% of vehicles deemed high profile, like semi trucks and buses, from crossing. All partial closures of the bridge are caused by high winds. While most closures have been for extreme weather, there have also been rare closures related to vehicular accidents on the bridge.

The bridge’s 15 hour, 45 minute total closure last week is the longest on the record for winter conditions. A prior partial closure for wind on November 13, 2005, also lasted 15 hours and 45 minutes, causing notable delays as it occurred two days before the start of Michigan’s deer hunting season and a significant portion of traffic that day was pickup trucks with bed toppers that were prevented from crossing because they are classified as high profile vehicles. The longest prior total closure was eight hours and 29 minutes in February 2014, when high winds blasted the bridge with whiteout conditions. Falling ice caused an extended closure in April 2008, when recurring conditions resulted in six hours of intermittent closure throughout the day.

When ice falls off the bridge, it usually falls in the direction the wind is blowing, however, sometimes it can tilt and fall in the opposite direction. A long-term ice event occurred at the bridge in January 2016 when ice the thickness of a soda pop bottle began building up on the bridge January 15 before freezing in place. The ice remained stuck until it began falling on January 23, leading to the decision to close the outer lane of the bridge while it fell, but still allowing traffic to use the inner lanes. The rest of the ice fell off January 26, causing another closure.

“Each event is slightly different,” Mr. Sweeney said. “In that case, the ice was so heavy we were confident the ice would only fall in the outer two lanes.”

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