Iowa issues video on innovative bridge construction technology.

The Iowa DOT, in cooperation with FHWA and Iowa State University, recently released a video and detailed report to inform the engineering community of a new bridge construction technology called "launching."

The Iowa DOT and its partners earned the FHWA Administrator's Environmental

Quality Award for their use of the technique to minimize the environmental impacts of a bridge crossing the Iowa River on U.S. Route 20. The bridge's steel girders were launched directly from the east embankment to the west on a series of concrete piers--without disturbing the ecologically sensitive river bottom. The technique entails assembling the bridge superstructure at a safe distance from the river and then launching the entire assembly longitudinally to its final location. To set bridge beams, contractors normally use a barge, crane, or work bridge that may disturb the ecological balance of the river they are working over. The process Iowa used, however, causes only minimal disturbance and may even be combined with the use of precast bridge elements to reduce construction time and further minimize impacts.

The project marked the longest total-launch steel bridge in the Nation and was named one of the top 10 bridges in the United States by an industry publication. Although launching typically is used to protect ecosystems, habitats, and archeological sites, the success of Iowa's project has encouraged researchers to look into the possibility of using the same technique to limit congestion and improve safety during construction.

To receive a free copy of the video and report, contact Max G. Grogg at 515-233-7306 or max.grogg@fhwa.dot.gov. For technical information, contact Ahmad Abu-Hawash at 515-239-1393 or ahmad.abuhawash@dot.state.ia.us.

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