The Utah Department of Transportation is using geofoam blocks — similar to the Styrofoam used in packaging materials and ice chests — to build a freeway ramp connecting the future West Davis Highway with southbound I-15 in Farmington.
Those blocks allow construction crews to build the new ramp in close proximity to I-15 as well as the Union Pacific Railroad and Utah Transit Authority tracks without causing additional shifting or settlement, explained Rex Harris, the agency’s project director for the West Davis Highway. “Sometimes there are unique challenges on our projects, and they require innovative solutions,” he said in a statement. “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, with each one weighing about 200 pounds and measuring approximately 4 feet by 5 feet by 9 feet.
Harris said 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, with concrete walls installed along the sides of the stacked blocks.
The weight of using dirt to build the ramp would cause the ground underneath to settle anywhere from several inches to a few feet, noted Utah DOT – a common issue in construction projects of this type, with engineers accommodating this “settling” with their designs. However, in this case of the West David Highway ramp, the close proximity of the existing interstate and rail lines meant they could be negatively affected by typical settling.
Utah DOT pointed out that it is one of a handful of state transportation departments in the United States with extensive experience using geofoam – a material first used in road construction in Norway in the 1970s. Some notable 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. Information courtesy of AASHTO.