US Highway 40, Berthoud Pass, East Side, Phases I, II and III
Clear Creek County, Colorado

Colorado Department of Transportation and J.F. Sato and Associates

Yeh and Associates has been involved with the project since 1999 as the subconsultant on the Environmental Assessment (EA) and Value Engineering services to improve safety and operational efficiency for approximately 6 miles of roadway widening on US Highway 40, which meanders through steep mountainous terrain on the east side of Berthoud Pass from the town of Berthoud Falls to the summit of the pass.

After successful completion of the EA, Yeh and Associates provided geotechnical engineering and design services for the preliminary and final design for the roadway widening. Mitigation measures were installed at several locations to minimize soil erosion and rock-fall potential. Due to the topography of the study area, most of the new alignment was designed with both cut-and-fill earth-retaining structures. The geology of the project area is complicated, with numerous fault features and complicated groundwater conditions. A major avalanche chute, marginally stable slopes, and an active landslide also occur within the project. Environmental concerns were a major issue throughout the project due to the sensitive alpine ecosystem, numerous wetlands, and the historic wagon trail.

The improvements for roadway widening included: retaining walls, an avalanche shed over the road, other avalanche structures, site grading and sediment control structures. Our work included: geotechnical investigations; geologic mapping of exposed bedrock structure; engineering analyses, design, review; construction monitoring and testing for numerous single and tiered soil nail, tieback, and MSE walls, soil and rock cut slopes, grading, and various structures on the project. We also designed the instrumentation program for the entire project, including inclinometers, piezometers, and load cells to monitor the long-term performance of the structures. Yeh and Associates participated in several interdisciplinary meetings between CDOT, the US Forest Service, and outside consultants such that the final project met all the agencies’ requirements.

Several of Yeh’s key personnel have worked on the project, Shan-Tai Yeh was the project principal and QA/QC reviewer, Rick Andrew was the project manager and Ben Arndt was the project engineer for the investigation and design phases. Bob LaForce provided pavement design input and was the materials manager during the 3 years of construction. Paul Macklin also worked on the project when he was with the MSE wall installation contractor.