DAKOTA CITY — On roads with lower weight requirements, counties have a way to save on bridge replacement costs — thanks to recycling and rail cars.

Humboldt County will keep a road open after its bridge failed using a culvert made from an old railroad tank car that may have once carried oil or ethanol.

“We’ve done it once in the past. We did it in 2014,” said Ben Loots, Humboldt County engineer. “It’s a cheaper alternative for a bridge replacement.

“Typically we do a concrete culvert because we can’t reduce the level of service of the roadway. With this one it’s only five to 10 vehicles a day, so it won’t be as difficult.”

This would be on 165th Street near Bradgate, he said.

The road is primarily used as an ag service road for farmers getting into the fields, and this fix will let it remain open, Loots said.

“With a box culvert you’re looking at around $120,000,” he said. “A railroad car is around half of that.”

At an earlier project, the county installed three rail cars, for a cost of around $90,000. The current project would only require one.

The bridge has been closed for six weeks since an inspection of all county bridges in November and December determined it was unsafe.

“Three of the pilings on the west side and one of the pilings on the east side were in bad enough shape they recommended we close the bridge,” Loots said.

Other options included rebuilding the bridge or closing the bridge and vacating part of the road. Landowners in the area were at the county Board of Supervisors’ meeting this week and said they wanted to see the road stay open.

Depending on how the old bridge comes out, county crews might not even need a crane.

“We won’t know until we actually do construction,” Loots said. “When we take the deck of this bridge off, if one of the abutments falls in, we’ll end up sloping it so we can just roll the pipe into the bottom, but if both abutments stay in place we’ll get a crane to set it.”

With the tank car in place, crews will backfill over the top with dirt and then put rock on the top, he said.

Construction will likely begin in summer, Loots said, when water flow will be low.

The discussion came as Loots is preparing his budget for the upcoming year.

The Humboldt County engineer’s office is responsible for a total of 721 miles of secondary roads, Loots said. About 204 miles are paved roads.

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Also, earlier this month the Humboldt County supervisors approved final payments for two road projects.

A final payment was made to Manatt’s Inc., Brooklyn, in the amount of $78,319.53 for its work on the Humboldt County Road C49 paving project.

A final payment was made to Rogness Brothers Excavating Inc., Lake Mills, for $2,105.01 for a couple of culvert replacement projects.