I-70 Mountain Corridor Programmatic Environmental Impact Statement, Denver to Glenwood Springs, Colorado

Colorado Department of Transportation and J.F. Sato

Yeh and Associates was the geotechnical and geological consultant in the preparation of a Programmatic Environmental Impact Statement (PEIS) for the 140- mile long I-70 mountain corridor from Denver to Glenwood Springs, Colorado. A number of different highway, transit and combination alternatives were studied. These alternatives included no action, minimal action, 6-lane configurations, reversible lanes, moveable median, fixed guideway transit and rubber tire transit.

Several different alignment variations were evaluated, with a focus on staying as close to the existing alignment as possible. Due to the difficult terrain, 15 tunnels, 17 landslides, multiple debris flow and rockfall hazard areas, and a constrained highway corridor, a geologic and geotechnical investigation was essential to any alignment improvement. There are several creeks that are directly adjacent to the existing highway thus potentially complicating construction and limiting modification alternatives to a narrow corridor. The very tight curvature of the existing four-lane highway has contributed to numerous accidents and has greatly constrained the ability for traffic to pass unencumbered. Satisfying future travel demands required a careful evaluation of potential improvement concepts as they relate to stakeholder concerns. A highly intensive public involvement and information campaign was undertaken using a context sensitive solutions approach. All alternatives were modeled based on travel demand forecasts for a number of scenarios. The study was sensitive to the recreational character of the highway as well as to the many businesses and residences that line the highway in a series of towns through which it passes.

Yeh’s key personnel that worked on the project included Rick Andrew who was the principal in charge and project manager, Ben Arndt was the project engineer and Roger Pihl was the project geologist.