When the clay beneath the roadbed of US 95 began to swell, the Idaho Transportation Department knew it had to look for different type of solution to this unusual problem. With the help of Boise State University, the agency began a two-phase research project to determine how expanding soils would impact that road. The research team determined that as clay attracted water, sections of the rebuilt US 95 roadbed experienced up to seven inches of swelling. Rather than trying to fight the water, crews instead worked with the water – displacing it rather than trying to eliminate it altogether. This $2.5 million project called for Geocells, a new material that – up until this point – had only been used in Israel. Geocells were placed on top of an already existing lime base, helping control soil swelling while reducing its impact on the roadbed. “Geocells are typically used for erosion control on the ground’s surface, so it was a new experience for ITD, the contractor, and the manufacturers of the materials,” explained ITD District 3 Project Manager Michael Van Lydegraf. Drivers on US 95 now have peace of mind knowing that the roads are safer and smoother for years to come.
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