Publication Number: FHWA-HRT-08-011
Date: March 2008

All About Steel Bridges

From design to fabrication to construction and maintenance, the World Steel Bridge Symposium 2007, held December 4-7, 2007, in New Orleans, Louisiana, brought together more than 300 attendees from around the world to discuss state-of-the-art practices for enhancing steel bridges. The symposium was sponsored by the Federal Highway Administration (FHWA) and the National Steel Bridge Alliance. "The symposium provided an excellent opportunity for practitioners to meet and network with others in the field, learn from their experiences, and build partnerships," says Vasant Mistry of FHWA.

FHWA held two presymposium workshops on Prefabricated Bridge Elements and Systems and Accelerated Construction Technologies. Projects highlighted in the workshops included the 24th Street Bridge project in Council Bluffs, Iowa. The two-span 24th Street Bridge over I-80 and I-29 will provide primary access to many major attractions and businesses in western Iowa, including casinos, an event center, and shopping centers. The Iowa Department of Transportation estimates that the project would normally take two construction seasons using standard construction processes but is accelerating the schedule to accomplish the work in half that time. Construction is expected to begin in 2008. Helping to accelerate the project will be the use of full-depth precast concrete deck panels that can be fabricated offsite and installed overnight, sparing drivers months of delays and reducing safety concerns for workers. Iowa will also use high performance concrete and high performance steel to improve quality, increase durability, and speed up construction. A structural monitoring system will be used to assess the integrity of the structure both during and after construction, while A + B (cost plus time) bidding will allow Iowa to select the most efficient bid by considering both construction cost and duration. The project received $1 million in funding from FHWA's Highways for LIFE program to support the use of innovative technologies and practices.

The Sauvie Island bridge in Multnomah County, OR, was transported by barge to the project site on December 28, 2007.

The new Sauvie Island bridge is lowered onto the bridge piers.

Also highlighted in FHWA's presymposium workshops was the collapse and restoration of "The Maze" interchange in the San Francisco Bay Area. After a portion of the I-80 eastbound to I-580 eastbound connector road collapsed onto the connector road between westbound I-80 and southbound I-880 in April 2007, closing two parts of a vital interchange that carried some 80,000 vehicles a day, the rapid repair beat all expectations. In just over a week, the roadway's damaged lower deck reopened to traffic and in less than a month, vehicles were traveling once again over the upper deck (see July 2007 Focus).

The symposium featured a range of topics, including integrated bridge project delivery and life cycle management, performance of steel bridges under thermally induced loads, methods of improving the fracture safety of bridges, analysis of steel girder bridges, and fabricated plate tolerances for steel bridges. Featured case studies included the replacement of the Sauvie Island Bridge in Multnomah County, Oregon. The bridge spans the Multnomah Channel of the Columbia River near Portland, Oregon. The five-span, 358-m (1,177-ft) replacement bridge has a 111-m (365-ft) steel tied arch main span. Using the steel tied arch reduced the number of piers in the channel and significantly increased the permanent navigation opening in the channel, meeting U.S. Coast Guard construction permit requirements and also satisfying stakeholders' preferences for an aesthetically pleasing bridge. The bridge was assembled on a dock 14 km (9 mi) away and then transported by barge to the site on December 28, 2007, where it was jacked into position. "Both the bridge move and the installation went very smoothly,"says Ian Cannon, Bridge Services Manager for Multnomah County.

The complete proceedings from the conference, including presentations and case studies, are available online at www.steelbridges.org. For more information about FHWA's prefabricated bridge elements and systems and accelerated construction workshops, contact Vasant Mistry at FHWA, 202-366-4599 (email: vasant.mistry@fhwa.dot.gov).

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