MDT Tests New Design Ideas with Hwy. 117 Improvements

The Montana Department of Transportation expects the paving project along Hwy. 117 between Nashua and Glasgow to be completed within the next two weeks, including the sloping and planting of grass along the finished roadway . The remainder of work and chip sealing will be completed next year.

Sections of the much-used roadway had been reported by residents as worsening every winter. After investigating the area, the damage was determined to be caused by “frost heave,” which is caused by a combination of soil types underneath the road and the soil absorbing moisture from nearby irrigated fields. When temperatures drop below zero and saturated soil under the pavement freezes, the pavement expands, causing it to raise. The flexing of the pavement causes the roadway to become distressed and damaged by eventually cracking the road’s surface as well as forming potholes.

To counteract frost heave, an experimental geotextile has been installed under the roadway to attempt to wick the moisture out from under the road and reduce stress on the pavement. The new section has 52 sensors and a weather station installed to collect data and evaluate the experimental feature of the project. The roadway sensors will measure soil temperature and moisture content and the data retrieved from these instruments will be used to evaluate the test section. The research will determine the effectiveness of the wicking geotextile and may provide a new, cost-effective design solution for prevention of roadway distress.

The scope of the construction runs roughly through 11.2 miles of Hwy. 117, beginning at the intersection with Hwy. 24 near Fort Peck and extends north to the Milk River Bridge near Nashua. The primary contractor on the project is Riverside Contracting, Inc., based out of Missoula, Mont., and the project has been overseen by an MDT inspection crew led by Engineering Project Manager Tony Charrette.

For up-to-the-minute conditions regarding Hwy 117, call 800-226-7623 or visit mdt511.com. More information regarding research on the experimental stretch of highway can be found at mdt.mt.gov/research/projects/tencate.shtml.