It was certainly the largest oversize load that Interstate 15 in Utah County had ever seen or likely ever will see, as the Utah Dept. of Transportation�s I-15 CORE team moved the 354-ft, four-ton Sam White Bridge into place over the new freeway overnight on March 26.

The event near the town of American Fork on a misty, cold Saturday night was not only a milestone for UDOT’s accelerated bridge construction (ABC) program but also the largest bridge in the western hemisphere to be moved using self-propelled modular transporters (SPMTs).

Transportation officials from across the United States and some from as far away as China, along with about 1,000 curious onlookers, watched as the structure was moved from the “bridge farm” on the east side of the freeway where the bridge was constructed, across eight freeway lanes (about 500 ft) and rotated into its east-west orientation over I-15.

The move began just after 11 p.m. and was completed around 4 a.m., well ahead of UDOT’s 7 a.m. Sunday estimate.

“We are able to do this by closing the freeway for one night rather than maybe the six months it would take if we did a traditional bridge replacement,” Njord said. “This is done as part of our design-build, best-value project, and we’ve been able to replace more bridges using this method than anywhere else in the country.”

While the crowds watched as the bridge slowly crept across the freeway, Steve Sarens, sales manager from Belgium-based Sarens Co., which builds the SPMTs, monitored the move closely, even though it is far from his first one. “We did the first bridge move and replacement like this in Europe in 1980,” he said.

Saren noted that the individual transporters, essentially hydraulic jacks on wheels, can be assembled into any number of configurations of four-axled vehicles forming what he called a “train.” The Sam White Bridge move was accomplished using four separate trains of 24 axles each.

The bridge, named for the long-time owner of the land adjacent to the bridge, was the 23rd ABC bridge completed by UDOT. Over the course of the $1.1-billion I-15 CORE reconstruction project, UDOT will replace, rebuild or modify 59 bridges. The project is scheduled for completion in December 2012.

John Njord, executive director of UDOT, said the rapid bridge replacement delivery method was part of the agency’s commitment to quality design and construction with a reduced impact to the traveling public.