No. 6 - Weld County Road 49 Design-Build

No. 6 - Weld County Road 49 Design-Build

Serving as one of the only major connections to Denver and the surrounding areas, Weld County Road 49 is a crucial farm-to-market corridor for the agricultural industry, and is a key thoroughfare for the regional oil and gas industry.

Before construction, the existing two-lane roadway was in poor condition and had reached the end of its useful life. It also had been considered one of the more dangerous roadways in the county, as it had numerous sight distance issues as well as over 200 accesses and 19 country road intersections without established acceleration/deceleration lanes or turn lanes.

“The goal of the project was to construct a roadway that addressed the safety concerns,” Greg Frazee, project manager of Interstate Highway Construction, told Roads & Bridges. The efforts to meet this need included building a four-lane roadway that permitted free passing; adding a dedicated left-turn lane so that traffic could exit the traffic flow while using the access; adding acceleration and deceleration lanes at county road intersections; eliminating all sight distance issues; and building a roadway that would withstand the heavy haul traffic and projected growth for the next 40 years.

The original plan was to reconstruct the roadway over a 10-year period with multiple smaller projects. But the roadway crosses two major floodplains, and is frequently inundated during heavy rainstorms. For this reason, as well as to mitigate costs and decrease traffic disruptions, Weld County opted for a two-year design-build (D-B) approach to complete the project, which became the largest contract let in the county’s history.

“The county taking on a project of this size and utilizing a design-build approach was a huge leap of faith,” Frazee said. Until recent years, Weld County had not constructed any major concrete roadways projects. In addition to accelerating project completion, the design-build approach allowed to the county to leverage the expertise of the D-B team to help fill in the gaps from the county’s inexperience with concrete roadway construction and larger projects.

The D-B delivery method fostered an innovative environment for the project, starting with the utilization of a Tensar geogrid to mechanically stabilize the subgrade in lieu of the originally specified R-40 subgrade. This also was the first major roadway project in the state completed with stringless paving control. And the existing roadway asphalt was recycled into the base course utilized in the concrete section.

All existing bridges within the project limits were raised to accommodate major flooding events and to eliminate inundation of the roadway. In only 14 months of actual construction time, the project removed and replaced 20 miles worth of outdated pavement, dirt, drainage and utilities. Despite some delays, the team was able to complete the project almost 30 days ahead of schedule.

Location: Weld County, Colo.

Owner: Weld County

Designer: Felsburg Holt & Ullevig (FHU)

Contractor: Interstate Highway Construction (IHC)

Cost: $109.6 million

Length: 20 miles

Completion Date: Dec. 1, 2017