Iowa Demonstration Project: Improvements to the 24th Street-I-29/80 Interchange in Council Bluffs.

摘要

As part of a national initiative sponsored by the Federal Highway Administration under the Highways for LIFE program, the Iowa Department of Transportation (DOT) was awarded a $1 million grant to demonstrate the use of proven, innovative technologies for accelerated bridge construction. This report documents the use of these innovations, such as cost-plus-time (A+B) bidding and prefabricated full-depth bridge panels used to accelerate the construction of the 24th Street-Interstate 29/80 diamond interchange in Council Bluffs in one construction season. This report details the innovation used to reconstruct the 24th Street bridge with precast bridge deck panels, high- performance materials, and innovative construction and contracting techniques. Innovations in this project increased safety, enhanced quality, and allowed the contractor to replace the 24th Street bridge in one construction season instead of two as would have been required for traditional construction methods. Using prefabricated deck panels and high-performance materials increased the initial construction cost by 12 percent over traditional construction. However, a more comprehensive economic analysis including user cost savings shows that the project saved road users about $1 million (or about 8 percent of the $12.7 million project costs). The experience gained on this successful project will help the Iowa DOT implement these innovations more routinely on future projects.