Making The Grade

摘要

State Highway 82 in Colorado is the primary two-lane route between Aspen and Glenwood Springs. The highway follows the general path of Roaring Fork River, which flows in a northwesterly direction from Aspen down to its confluence with the Colorado River. Under the auspices of the Colorado Department of Transportation (DOT), a project was begun in the 1990s to expand a 3.4 mi (5.5 km) section of the state highway in Snowmass Canyon from two lanes to four, creating two up-valley (Aspen-bound) lanes and two down-valley (Glenwood Springs-bound) lanes. The original environmental impact statement was submitted in 1991, the record of decision coming in 1993. Preliminary design work began in 1995, and work on the final designs began four years later.Yeh and Associates, of Denver, carried out geological and geotechnical investigations in 1999 and the following year provided retaining and foundation designs. The up-valley lanes were to traverse the slopes above the existing two-lane highway, whereas the down-valley lanes would follow the general alignment of the existing highway. It was necessary to realign and raise the elevation of the existing lanes to accommodate current highway design speeds, expected traffic volumes, and sight distances.