Clayton County takes on aging bridge problem
Thirty percent of Clayton County's bridges are deemed either structurally deficient or functionally obsolete, according to the U.S. Department of Transportation. (Press photo by Austin Greve)
By Pat McTaggart
Freelance Journalist
An Aug. 14th headline on the front page of the Des Moines Register stated “Iowa infrastructure makes ‘worst’ list." The article noted that, according to the U. S. Department of Transportation, about 20 percent of Iowa’s 24,215 bridges are deemed “structurally deficient.”
Of Clayton County’s 233 structures that the federal government classifies as a bridge, 48, or 18 percent, are structurally deficient. Another 28, or 12 percent, are functionally obsolete.
“Structurally deficient means that one or more of the members of the bridge has deteriorated to the point that the load capacity needs to be reduced,” County Engineer Rafe Koopman said. “Functionally obsolete means that they are in good shape but the design does not meet current criteria such as the ability to carry legal loads or the correct width.”
According to the Iowa Department of Transportation website, “a bridge with a poor condition index is not unsafe but should be considered for repair, replacement, restriction posting, weight limits or monitoring on a more frequent basis.”
“All of our bridges are inspected every two years and they are all analyzed to determine the safe load that can cross the bridge,” Koopman said. “If it is determined that legal loads cannot safely cross the bridge a load posting sign is installed. These signs need to be obeyed.”
Koopman said that the county’s structurally deficient bridges need replacement more than rehabilitation. “A lot of those needing replacing were built in the 30s, 40s and 50s, and the materials used to build them were not made to last this long,” he said. “We get enough funding to replace about two bridges every three years.”
The county is trying to speed up the process of replacing some of the smaller-sized structures. “We are getting scrapped-out railroad tank cars from Clayton County Recycling,” Koopman said. “They can be used to replace those smaller structures. We have replaced at least four already, and can use them to replace some more, but they will only work on smaller drainage areas. Since the county is using Secondary Roads employees on those replacements instead of farming out the work, we are spending about half as much as the next alternative.”
Although some bridges are taken off the list as they are replaced, new ones are also added as they age. “The replacement work is definitely an ongoing process,” Koopman said.
