One major benefit of geofoam is its lightweight property which translate to a reduction of weight in structures. In the case of side hill projects, the lighter the fill, the better. The reduction of weight and pressure against the side of the hill is used to prevent landslides, and stabilize the hill side. The lack of increased weight on the side of the hill allows for a safer, more stable road construction project.
As a rule of thumb, geofoam is up to 100 times lighter than other traditional fills with similar compressive strengths. It can bear more capacity than most traditional fill materials as well, making it a solid option for hill construction.