Special tower stand jacks raised and lowered the span off the temporary supports and onto the new substructure elements, respectively. Chains were also used to help control the distance between the double lines of SPMTs. On the top of the bridge, piano-like wire was placed at the diagonals of the span to measure any span distortion. To avoid overstressing the deck concrete, only inches of distortion was allowed. The span superstructures were placed late Friday evening into early Saturday morning, and late the following Sunday night into early Monday morning, with minimal traffic restrictions and lane closures.

MassDOT: 14 in 10 Weekends

This summer, Massachusetts DOT achieved a remarkable bridge replacement record, with 14 bridges replaced in Medford, Mass. over 10 weekends from June to August with its I-93 “Fast 14” Rapid Bridge Replacement Project.

Because MassDOT used cutting-edge accelerated bridge construction techniques and materials to replace the bridges, all the bridge and associated work was completed over a five-month period.

“Using conventional methods, it would have taken at least four years to replace all 14 bridges, and during those four years drivers would have had to endure long-term lane closures,” MassDOT says. “MassDOT executed a traffic management plan and a comprehensive communications plan to minimize construction-related congestion and community impacts during construction, which was limited to off-peak hours.”

The innovations MassDOT used to accelerate the bridge replacements include design/build procurement, a prefabricated bridge elements system and a special rapid-setting concrete. “By replacing the bridges with modular superstructure units that were fabricated off-site, MassDOT eliminated years of work in the roadway,” the agency says.

This project was showcased by FHWA, receiving national attention for the innovation it used to get the bridges built so quickly and safely, and for limiting major impacts to road users to off-peak hours.

Prefab Speeds

Access Overpass

Even before Utah and Massachusetts, the Georgia DOT used extensive prefabricated bridge elements and systems to radically reduce the time and cost of a new bridge over I-85 in Troup County, as part of an improvement to provide access to a new Kia vehicle assembly plant there.

On the Utah I-15 project, a self-propelled modular transporter (SPMT) moves superstructure into position between bridge bents.

Georgia DOT Commissioner Gena Evans said at the project’s dedication in December, 2008 that the project was an enormous achievement, considering a tight, 18-month construction timetable that had to be met. Work was finished more than 30 days ahead of that schedule in the largest design-build construction project initiated by Georgia DOT.

“This effort proves that design-build can be successful when applied to the right projects,” Evans said. “Georgia DOT is proud to have played a role in helping to bring new jobs and improved mobility to the area.”

Though Kia was located near I-85, access to the highway was limited. Existing roads could not accommodate the estimated thousands of additional daily auto and truck trips, and a bridge was needed. To expedite construction, Georgia DOT chose prefabricated bridge elements and systems.

“With PBES, innovation could be incorporated into the design without increasing the user costs,” the DOT says. “Conventional bridge construction, using cast-in-place technology and traditional contracting methods, would have required 30 months. With PBES, the project was completed in only 16.5 months.”