“Sometimes there are unique challenges on our projects, and they require innovative solutions,” said Rex Harris, UDOT Project Director for the West Davis Highway. “Geofoam is another tool in our toolbox to efficiently build the roads, trails, and bridges we all need to get where we want to go.”
The ramp to southbound I-15 is being built with approximately 3,000 geofoam blocks. Each one weighs about 200 pounds and measures approximately 4 feet by 5 feet by 9 feet. The blocks are brought to the construction site and then either placed as-is or cut to fit as needed. Once all the blocks are in place, a concrete slab is poured on top to evenly distribute the load of the ramp pavement and traffic, and concrete walls are installed along the sides.
The weight of using dirt to build the ramp would cause the ground underneath to settle anywhere from several inches to a few feet. This settlement is typical in construction, and engineers accommodate this settling with their designs. However, in this case, the close proximity of the existing interstate and rail lines meant they could be negatively affected by typical settling.
UDOT is one of a handful of state transportation departments in the U.S. with extensive experience using geofoam. Some projects that also used geofoam include the I-15 reconstruction in Salt Lake County prior to the 2002 Olympics; the 1100 South bridge over I-15 in Brigham City; and the 5600 West bridge near 700 South in Salt Lake City. The material was first used in road construction in Norway in the 1970s.