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Sam White Bridge Span Moved Overnight

The Challenge:
Move a 354-foot, two-span bridge into place over Interstate 15 in Utah in one night's time.

The Players:

Provo River Constructors
Utah Department of Transportation

The Process:
The Sam White Bridge, located 30 miles south of Salt Lake City, is one of 59 new, modified or rebuilt structures on a 24-mile interstate reconstruction project. The design-build project is being constructed by Provo River Constructors (PRC), a consortium of 30 plus companies led by Fluor Corporation, Ames Construction Company, Wadsworth Brothers Construction Company and Ralph L. Wadsworth Construction Company. The contract, issued through an innovative fixed-price, best-design procurement process, was awarded in December 2009. Construction began in April 2010.

Construction of the Sam White Bridge began in July 2010. PRC proposed using Accelerated Bridge Construction (ABC) technology to reduce delays from months to days to meet the project's aggressive three-year timeline. This innovative approach at Sam White eliminates the need for six full freeway closures, reduces traffic delays and aides the state's economic recovery by keeping people, goods and services moving during construction of the freeway. Six additional full nighttime freeway closures would have been necessary to rebuild the bridge using traditional methods. The bridge was built on the east of the freeway in a "bridge farm" using ABC from July 2010 to March 2011.

A two-span steel-plate girder option was chosen for the Sam White Bridge due to its light weight and its ability to follow the profile grade line. Sam White Lane crosses I-15 at a very high skew and on a sharp vertical curve with the crown essentially at the center of the center bent. The approach slabs each have a grade of approximately 7.3 percent.

The superstructure uses six girders at 13 feet 6 inches spacing with a 4 foot 8 inch overhang. The structure depth is approximately 7 feet 1 inches including a 10-foot deck. The girders use 70 ksi steel in the flanges over the bent and 50 ksi steel everywhere else. The framing plan uses staggered perpendicular cross frames up to near the bent. Near the bent the cross frames go to a continuous line across the bent with each line intersecting the girder at the column. The bent does not have a cap; each girder sits directly on a 4-foot square column. The high skew and large girder spacing make the girder spacing along the bent approximately 20 feet. The elimination of the bent cap more than makes up for the additional column(s). The girder/column connection uses an innovative interlocking sole plate and masonry plate detail, which allows seismic loads to be transferred into the column while allowing girder rotation and transverse movements due to temperature effects. An oversized sole plate allows for setting tolerance during the bridge move. Each sole plate sits on a steel-reinforced elastomeric bearing pad.

The foundations consist of 12-foot concrete-filled pipe piles driven approximately 100 feet through soft clays and tipped in a medium-dense silty sand. The abutments are made integral after the move.

On March 26, 2011, the Sam White Bridge over Interstate 15 in American Fork, Utah, made history in just one night. It is the longest two-span bridge ever moved by self-propelled modular transporters (SPMTs) in the Western Hemisphere. Crews set the bridge into place at approximately 4 a.m. Sunday and reopened the freeway at 7 a.m., three hours ahead of schedule.

Two sets of SPMTs - hydraulic jacks on wheels, controlled by a single joystick - were used to lift the 354-foot, 3.8 million-pound structure 21 feet in the air. The two-span bridge was moved simultaneously from the "bridge farm" where it was constructed on the east side of I-15 across eight freeway lanes (approximately 500 feet) and lowered into place.

The 27,500-square-foot bridge area contained 1,134 cubic yards of concrete, 1.47 million pounds of steel, 275,350 pounds of rebar, and took 12,700 hours to construct and move the bridge.

To get a visual idea of the process of moving the bridge, check out this time-lapse video of the move.

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