US 6 Bridge over Keg Creek

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  • Mar 5, 2012

In 2010, the Iowa DOT began work with the Transportation Research Board (TRB) Strategic Highway Research Program 2 (SHRP2) to participate in a demonstration project involving accelerated bridge construction (ABC).

The bridge on US 6 Bridge over Keg Creek in Pottawattamie County was chosen as the test site because it had features typical of other 3-span structures in Iowa and surrounding states.

The structure was completely prefabricated off-site and was constructed using a steel and a precast concrete modular system that included epoxy-coated reinforcing steel. The exterior modules also included traffic railing.

The prefabricated components included: abutting deck/beam elements, straddle caps, columns, parapets, and approach slabs. The project used ultra high performance concrete (UHPC) for the deck closure joints and was the first structure in the United States to use UHPC in the transverse continuity joints. The project also utilized a self-compacting backfill concept for rapid abutment construction - and was constructed in its entirety using conventional on-site construction equipment.

Speed of Construction
ABC required the road to be closed for only 14 days, unlike traditional construction methods that would have required the partial or complete closure of the road for several months thus resulting in substantial traffic disruption.

The bid price for the demonstration bridge project was $2.6 million, approximately 30 percent more than a similar three-span conventional bridge.