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Brent Spence Bridge closure: What are engineers, inspectors looking for?

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Posted at 10:29 PM, Nov 12, 2020
and last updated 2020-11-13 12:43:18-05

CINCINNATI — It may take more than a month for the Brent Spence Bridge to reopen as authorities on both sides of the river assess damage following a fiery crash that shut down the interstate bridge Wednesday.

Just how deep the damage goes will determine how long it takes to reopen the bridge. No matter what inspectors find, engineering experts said it’s unlikely the solution will be a simple one.

One of the two semi tractor trailers involved in Wednesday’s crash was carrying potassium hydroxide, which caused the fire to burn hotter and longer. Crews battled the blaze for about two hours before it was extinguished.

RELATED: State of emergency declared in Kenton Co. after Brent Spence closed indefinitely

Stephen Ayers, assistant dean and professor of civil engineering at Cedarville University, said that chemical fire is likely to have caused damage to steel and concrete that a casual observer won’t be able to see.

“You are talking about something that’s in the middle of the bridge -- 1500 degrees in steel is not going to melt the bridge at that temperature. What it’s going to do, though, is change it basically at an atomic level and at a micro-structural level,” Ayers said. “It will change the steel.”

Past president of the American Society of Civil Engineers Andy Herrmann agreed, adding that assessing damage from such a fire would cause further delays.

“It takes time to do that,” Herrmann said. “They may also take samples of the materials and send it out for testing to see if it’s been damaged by the extreme heat over the period of the fire.”

Hermann said crews will also have to carefully inspect the bridge’s main load carrying members, the tresses, for damage.

“It’s a very rare occurrence,” Herrmann said of possible heat or impact damage in the tresses. “In the last maybe 20 years, I can think of maybe three or four that happened in the United States.”

MORE: How to get around while Brent Spence is closed

Both experts, with decades of engineering experience between them, said multiple, large-scale specialty pieces for the bridge may need to be rebuilt off-site before they are carefully transported and installed. That, all while making sure the bridge can withstand the weight of the equipment used to fix it. Ayers explained it's a difficult scenario for many reasons.

“You’re up high in the air," he said. "You’re over a river. The river’s got river traffic on it and things like that, too, so you have to make sure that that’s safe.

“You’ve got potentially significant structural damage to that bridge and it’s not like we’re talking about repairing a wall in your house or something,” he said. “This is a big structure.”

A major interstate thoroughfare, the Brent Spence Bridge carries between 150,000 and 200,000 vehicles each day when it’s open, and it's a crucial trucking corridor. That means despite the complexity of what comes next, ensuring both speed and safety of repairs is key.

RELATED: Bridge closure could impact more than just regional traffic, trucking expert says

“They’re calling in a lot of people to try and speed up the whole process, which is good in emergency condition,” Herrmann said.

But whether this will be a tipping point for a total replacement down the road remains to be seen.

“I think the debate over what’s the long-term solution is something that will continue,” Ayers said.

Kentucky Transportation Cabinet Sec. Jim Gray said the inspection process is ongoing and will take at least several days just to determine what repairs are necessary.