County saves money replacing bridges

MARENGO — Iowa County’s secondary roads department has learned to build bridges, and it’s saving the county money.

Every year the county replaces several bridges that have deteriorated.

“We start with the embargo map,” said Iowa County Engineer Nick Amelon.

Every bridge is inspected every two years to make sure it’s able to handle a certain load, said Amelon.

If it has deteriorated to a point that it can no longer handle the load it was built to handle, the bridge is posted with a weight restriction, an embargo.

Iowa County hires Calhoun-Burns and Associates to inspect its bridges.

When deciding what bridges to replace, Amelon has to consider not only how bad the bridge is but how much the county will have to spend to fix it, what kind of road it’s on, how big it is and where the funding will come from.

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“This year our crews are going to do these four,” said Amelon, pointing to a map of the county. Two of the replacements, a culvert on I Avenue West of Marengo and a new bridge on H Avenue southeast of Ladora, have been completed.

One bridge was replaced with a box culvert, and the other with a new bridge.

County crews are replacing a bridge on 150th West of Marengo with an aluminum culvert. A bridge on 190th southeast of Ladora is being replaced with a large box culvert.

The bridge cost about $200,000, the box culverts about $140,000 and the aluminum culvert about $80,000, Amelon said.

That includes materials, equipment and labor.

The county also designed two bridges which Taylor Construction will build.

“They have to be contracted out,” said Amelon. “They are so big the DOT will not let you build them yourselves.” One is 150 feet long.

Those bridges cost $450,000 and $800,000.

Federal funds pay for the large bridges, said Amelon. The two bridges southeast of Ladora will be paid for with tax increment financing from the wind turbine project in the county.

The bridges west of Marengo are being replaced using local funds.

“This past year prices have stayed the same,” said Amelon, but the two previous years construction costs rose 30% and 20%.

Because a construction company has to make a profit and the county doesn’t, having the secondary roads department replace the bridges saves the county about $70,000 for each project, Amelon said.

The bridges the county replaces itself are 33-35 feet, said Amelon. The culverts replace smaller bridges, those about 19 feet long.

“We’ve always done [the box culverts],” Amelon said. The county has built nearly 20 in the last 10 years.

When county workers mastered the box culverts, they moved on to aluminum culverts, Amelon said. They’ve done three or four aluminum culverts in the last few years.

The county started building its own bridges about three years ago and have completed three.

“Now they’re really good at building all three,” said Amelon.

Whether or not the county can replace a bridge with a culvert is based on the size of the bridge and how large an area drains to that bridge.

A culvert drains 1,000 to 2,000 acres, said Amelon. A bridge will drain 3,000-4,000 acres.

The county replaces four or five bridges a year. “I think that’s a pretty good number to get done,” Amelon said.

“You always want to do more,” said Amelon. “We’re going at a pretty good clip.”

Next year the county will replace one large bridge on D Avenue north of 210th through the Iowa Department of Transportation with TIF funds and will replace three or four itself.

Most of the bridges they’ll replace are embargoed at 15 tons or less.

The county works on two bridge projects at a time, said Amelon. Four to six guys work on each project.

“It’s really good that our crews are very good at putting these together.”