Geogrid provides alternative solution to cold weather construction challenges David Lipomi Regional Sales Manager Tensar International Corporation Pittsburgh, Pennsylvania ough subgrades and cold winters can lead to frost heave and dangerous roads. When the spring thaw hits, the damage can quickly become a safety hazard. Typically, crews can’t rebuild heavily used and damaged roads during the winter, making the situation worse. One project contractor in Pennsylvania discovered an alternative solution that saved him time and money and allowed crews to rebuild the road in frigid temperatures. Winter weather creates unsuitable road conditions A 9.5-mile unpaved forestry arterial road in Clearfield County, Pa., was being used to explore natural gas formations in the area. But intense snowfall and ice coupled with heavy truck traffic had created unstable road conditions. The project owner, an oil and natural gas company, was searching for an affordable way to restore the road, and he needed to be able to use products that could withstand cold climate construction. The road was decades, perhaps centuries, old, according to Marty Lentz, Assistant District Forester, Pennsylvania Department of Conservation of Natural Resources (DCNR). While the road serves as an arterial and supports secondary roads that provide critical access to vast areas of the forest, it was never really designed for year-round use, especially by heavy trucks. But this was exactly the type of access the oil and gas company needed to explore for the natural gas deposits hidden 52 APWA Reporter
November 2012
deep in the Marcellus Shale Formation underlying much of the region.
Restoration agreement requires more durable roadway After a few years of use, it became clear that year-round heavy traffic, in combination with significant snowfall, “ice lensing,” and existing soft subgrade soils (CBR = 1.0), was causing significant deterioration to the road during the annual spring thaw cycle. To correct this situation and maintain access to this valuable site, the company signed a restoration agreement with the DCNR in which the company committed to create a year-round surface that could support public access for up to 1,000 heavy-vehicle trips per day.
During preliminary planning, the company’s consultants considered using soil cement with a new 33-inch-thick aggregate top layer. They also evaluated the benefits of installing a geosynthetic material in combination with an aggregate top layer, but these solutions were rejected due to concerns over environmental impact, cost and performance. A high-performing, affordable solution After carefully considering the project requirements, the company selected the Spectra® Subgrade Improvement System with one layer of Tensar® TriAx® TX7 Geogrid as the best solution for stabilizing the roadway for public and commercial
The unique properties of TriAx Geogrid allowed for a reduction in aggregate requirements that led to an estimated $1.4 million in savings.
