Iowa County Builds Bridge Without Typical Concrete Materials

A forty-foot-wide bridge in Buchanan County is drawing attention for its unconventional building materials. Instead of the traditional concrete beams and bridge abutments, the bridge was built with wooden beams and geo-synthetically reinforced soil (GRS).

“If you look at the beams there on the bridge, those are two by 12 sections of wood that are pressure treated and glued together so pressure treating them keeps them from decaying,” said Buchanan County engineer Brian Keierleber.

The GRS technique mixes tough fabric with gravel in layers.

“You don’t need large equipment to set this material or build these bridges as the county engineer showed, you could do it with a county work force, and smaller numbers of less skilled labor,” said Travis Hosteng a bridge research engineer at Iowa State University’s Bridge Engineering Center.

The bridge office at Iowa State will have both cameras trained on the bridge and sensors built in to monitor the stresses of daily traffic. Engineers who are interested can call up images or data in real time to see how this unusual bridge is doing.

(more on the unique new Iowa bridge construction...)