116 3rd St SE
Cedar Rapids, Iowa 52401
During a routine bridge inspection in rural Johnson County this spring, inspectors made an unfortunate discovery.
The bridge southwest of the city of Tiffin had structural damage.
“Our structural engineering consultant had noticed some damage underneath that was more advanced than we had hoped,” said Ed Bartels, assistant Johnson County engineer. “Some of the beams had started to buckle.”
The extent of the damage prompted the county to close the bridge. Bartels said it will have to be replaced and estimated the costs at somewhere around $500,000 to $750,000.
That challenge isn’t restricted to Tiffin.
All told, approximately 492 bridges are closed across the state, according to the Iowa Department of Transportation. An additional 5,018 have some sort of restriction, and the remaining 18,436 have no restrictions.
Nearly one in five of Iowa’s bridges — 19.1 percent — are structurally deficient, meaning a key element of the bridge is considered to be in poor or worse condition, according to the American Road and Transportation Builders Association.
That places Iowa second in the nation for the percentage of structurally deficient bridges, just behind West Virginia.
Iowa leads the nation in number of structurally deficient bridges, according to the ARTBA, a Washington, D.C.-based trade association that releases a national bridge inventory each year based on data collected by the Federal Highway Administration.
“Iowa usually is at the top of our rankings,” said Alison Black, chief economist for ARTBA. “That’s definitely not a good thing. That’s not where you want to be.”
However, one Iowa DOT official said those rankings are a little misleading and that Iowa’s bridges are safe for the traveling public.
According to the ARTBA report, Iowa has 4,571 structurally deficient bridges. Black said that means the deck, superstructure or substructure is in poor or worse condition. Bridges are inspected every two years.
The report also notes that Iowa has identified repairs that are needed on 15,308 bridges at an estimated cost of $3.1 billion. That’s a slight increase from the 15,178 bridges found in need of repairs in 2016.
“Often, these can be very costly projects,” Black said. “It’s going to take additional resources from all levels of government to really make significant progress. We’ve seen things improve, but it’s at a very slow pace.”
Rural bridges a factor
Black also notes it’s not uncommon for states with a lot of rural bridges — such as Iowa — to rank high on the list.
After all, more than 11,600 of the bridges in the state are rural, Black said. Of the structurally deficient bridges, 99.5 are not part of the National Highway System and only six are on the Interstate Highway System.
When people look at Iowa’s rankings on the ARTBA report, officials want them to consider the big picture, said Scott Neubauer, state bridge maintenance and inspection engineer for the Iowa DOT.
“There are a lot of factors that have to be looked at other than just a raw total number of bridges,” Neubauer said. “We don’t like being No. 1 and having the highest number of deficient bridges by any means. But you have to look at … can the bridges handle the traffic they’re seeing?”
Neubauer said the majority of poorly rated bridges in Iowa are mainly on the state’s local roads and see low volumes of traffic.
“About half that are considered poor in Iowa have less than 35 vehicles a day that cross them,” he said. “You’ve got to look at it in perspective there.”
The bridges themselves also are small, Neubauer added. When considering only poor deck area — the part of the bridge you drive over — Iowa drops from first to seventh in the nation, Neubauer said.
And just because a bridge is in “poor” condition doesn’t mean it’s not safe to be traveled on, he said.
“It can handle the traffic it’s seeing,” Neubauer said.
Lifetime of a bridge
Neubauer said Iowa has reduced the number of poorly rated bridges on the state highway system by “a very large margin.”
Around 12 to 15 years ago, 250 bridges on the state highway system were rated poor.
“We’ve steadily decreased that number,” he said. “Now we’re in the low 30s. We’ve made a concerted effort to reduce that number.”
More work for the state looms on the horizon, though. If you’re lucky, a bridge will last 100 years. But even at that number, with more than 4,000 bridges in the state highway system, that means replacing 40 bridges a year to keep pace with the aging infrastructure. Bridges built in the last 50 to 70 years will have to be replaced even sooner, Neubauer said.
“At some point in the future, we just won’t be able to maintain that without some additional funding,” he said.
With some counties having to spend $1 million or more to replace a bridge that has “minimal traffic,” officials have to be practical in how they invest money in infrastructure.
Bartels in Johnson County said local officials have made an effort to keep rural bridges open — but that’s not the case everywhere.
“We’re a little bit different from most other counties,” Bartels said. “Our (board of supervisors) has made a real effort to keep those bridges open. Most counties tend to close them.”
But even in Johnson County, where transportation and infrastructure are a priority, keeping up that funding can be a challenge.
“There’s never enough money to do all the work we’d like to do, even in Johnson County,” Bartels said. “Things are only worse in a lot of other places.”
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