Roadways often have to be widened to reduce congestion. This situation results in additional fill being required for the roadway to be widened. This can be an expensive and time-consuming process if the soils adjacent to the existing roadway are not adequate to support the traffic loads because the resulting settlement can impact the existing roadway. In traditional construction, soil embankments are built in thin lifts, each of which must be compacted before the next lift is placed. Using EPS geofoam eliminates the need for compaction and fill testing, reduces the construction time and minimizes impact to the existing roadway and adjacent structures and/or buried utilities. The high compressive resistance of EPS geofoam makes it able to withstand the induced traffic forces without causing unacceptable loading of the underlying soils or adjacent fill. In addition, it may be possible to build steeper slopes using EPS geofoam than soil, which can reduce the amount of additional right-of-way that needs to be acquired.
The largest EPS project in the United States was the widening of I-15 in Salt Lake City, Utah where, from 1997 to 2001, approximately 130,800 cubic yards (100,000 cubic meters) of EPS geofoam was used to reconstruct parts of the interstate to facilitate the 2002 Winter Olympics.
In some locales, numerous pre-existing buried utility lines traversed or paralleled the interstate in the widened areas. These utilities consisted of high pressure gas lines, water mains and communication cables, all of which needed to remain in-service during construction. However, placement of conventional soil for the embankments in the widened areas would have produced as much as 3.3 to 4.9 feet (1 to 1.5 meters) of settlement, thus exceeding the strain tolerances of the buried utilities. The use of EPS geofoam in the utility areas essentially eliminated these large and damaging settlements and allowed construction to proceed rapidly without expensive interruption, replacement or relocation of the utilities.