Monitoring firm dismissed Lansing bridge movements until it was too late

By Samantha Ludeking, Driftless Journal Production Manager

Bridge decks have been removed from the east side of the Black Hawk bridge to make repairs to the piers underneath. In this photo taken Thursday, March 14 the removed decks can be seen on the south side on the bridge. (Driftless Multimedia photo by Samantha Ludeking)

Sixty people were in attendance in person – in addition to many more who tuned in online – Thursday, March 14, at Lansing’s Meehan Memorial Library for the first monthly “Bridge Talk” since the Blackhawk Bridge was closed due to movement detected Feb. 25. Iowa DOT Project Manager Clayton Burke discussed the movement on the over 90-year-old bridge, the repairs being done to allow the bridge to re-open and how the damage has affected the construction of the new bridge. 

Closure

Local residents Mark and Fred Rethwisch alerted authorities of visual changes on the Wisconsin side of the bridge deck on Sunday, Feb. 25.

“You could clearly see that there was a kink in the bridge,” said Burke, explaining what he saw upon arrival at the scene. “Something had obviously moved, and we didn’t know what condition the bridge was in, so we closed it to make sure that nothing additional happened.”

A structural inspection firm was called in and found that the bridge had, in fact, moved. The existing pier six of the bridge moved six inches from north to south and settled five inches down into the ground. Pier seven moved as well, the firm found. 

“It was quite a bit of movement,” said Burke. “We weren’t expecting that, and we started looking into right away, what can we do to get this bridge back open because it wasn’t acceptable to have it closed.” 

Repairs

The repairs are underway and involve a crane removing and setting aside the bridge decks while the piers are repaired. Therefore, the bridge cannot be open to even pedestrian traffic. Burke estimated the current “fiasco”, as it was referred by several residents in the crowd, has a rough price tag of around $2.5 million and sets the bridge building project back by a couple weeks. Burke also estimated that the bridge will be repaired and open by the end of April.

The governor’s proclamation activates the Federal Highway Administration (FHWA) Emergency Repair (ER) Program which authorizes emergency relief funding to cover the costs of repair or reconstruction of federal-aid routes that have suffered severe damage as a result of sudden structural failure.  

“Unfortunately, we had an off-site company that provided the sensors and were monitoring the data,” Burke said. “And, the sensors they installed relied on solar power. So, over the winter, it’s been cloudy over half the days, and those sensors were losing power at regular intervals because the batteries they were connected to were running out of power.” The GPS sensors would periodically go offline, and when they’d come back online, they showed readings of movement that the company thought was just the sensors malfunctioning, when the bridge was actually moving.

“They didn’t provide any notice or alerts to us,” he said. “The way that they are supposed to function is that if the bridge moves a certain amount, we get an alert that tells us that something happened, and we didn’t get those alerts.”

“You are talking about an error that was made by this company, what’s their liability for the delay in the bridge construction and how that is affecting the city?” asked Eastern Allamakee Community School District Superintendent Dr. Sarah Murray.

“That’s a really complex discussion that we are having right now,” Burke replied. “It’s going to take a while to sort all those cards out.”

While vibration could be a contributing factor according to Burke, it’s really hard to know if there are other factors. “You can’t see into the ground and know exactly what happened. The only thing we can understand is how vibration impacts the bridge,” Burke said. “That’s why we did vibratory tests out near the other piers is to make sure if we vibrated something next to them, that vibration isn’t going to cause any movement. This is giving us confidence that continuing construction isn’t going to have an impact on the existing structure.” 

Burke also said that while the public may be concerned about sensors on other piers, Burke’s office isn’t only relying on the sensors but optical surveying as well.

“So, we know those (other) piers did not move,” he said. “Going forward we are going to use those optical surveys during critical operation just to make sure that we are not relying on that GPS system.”

When concern was raised about semi traffic once the bridge reopens Burke assured the crowd, “The repairs we are working on are going to restore it to the full original condition.”

The contractor building the new bridge, Kraemer North America, had been using concrete from Croell’s Lansing location, but with the closure of the bridge, the concrete is now coming in from Viroqua, Wis. Burke reassured concerned residents that the contractor would return to using “Lansing concrete” to build the Lansing bridge as soon as possible. 

Water taxi

Since the nearest alternate bridges for vehicle traffic to cross the Mississippi River are at La Crescent, Minn./Lacrosse, Wis., or Marquette/Prairie du Chien, Wis., the DOT has arranged for a free water taxi across the river during the bridge closure. The water taxi is accessible to all riders and will shuttle between the Lansing Marina on the Iowa side and the Big Slough Landing on the Wisconsin side. 

The service will be available seven days a week (see shuttle schedule in the graphic below). A one-way trip is estimated to take about 30 minutes. All riders must get off the water taxi at each stop. A ground shuttle will run from Lansing City Hall and Kee High School to the marina on the Iowa side. On the Wisconsin side, the shuttle will run from the Big Slough Landing to the De Soto Community Center. There will be no parking at the Big Slough Landing. 

Burke reported that the DOT considered a vehicle ferry, but there isn’t a large enough access area at the Big Slough landing.

Bridge Talks will be held the second Thursday of each month at the Meehan Memorial Library in Lansing. The public is welcome to attend.

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