Weld County Road 49 Design-Build: I-76 to US 34, Weld County, CO
Contractor: Interstate Highway Construction, Inc.  
Owner: Weld County, Colorado, Division of Engineering
Engineer: Felsburg Holt & Ullevig

As the first design-build pavement project for Weld County, this was also the largest single contract awarded in the county’s history. The selection of concrete pavement was a big step for the owner, which historically used their own asphalt paving crews and, until recent years, had not constructed any major concrete roadway projects.

As one of only two major north-south farm-to-market routes within the County, WCR 49 is essential to the area, but the existing roadway was also one of the most dangerous in the county. About 53% of the traffic is from heavy haul trucks serving the local farming/ranching and oil/gas industries. Roadway conditions and numerous sight distance issues meant the failing roadway needed attention. The roadway crossed two major flood plains and was often inundated during heavy rainfall events. Considering all these factors, county officials expedited the roadway reconstruction and issued the two-year design build-effort project in place of one originally planned for 10 years.

The design-build team was challenged to eliminate the sight distance issues; provide acceleration/deceleration lanes at most of the project’s 19 county road intersections; eliminate overtopping of the roadway; establish both a general purpose and passing lane in both directions; and create a full-length 16 ft. center turn lane.

The project also involved 183 private parcel acquisitions and relocation of almost 110 miles of existing utilities. The right-of-way acquisition was completed until almost nine months after the notice to proceed was issued, and in turn, this slowed the utility work and delayed the overall project by six months.

The design-build team worked closely to identify and address environmental impacts. IHC completed environmental surveys for wetlands, historic resources and potential hazards along the corridor and the designer then incorporated information into the design to minimize potential impacts.

The total project length was 19.96 miles and included 937,000 SY of concrete paving over 19.96 miles. The project called for 500,000 tons of aggregates for the concrete. Transporting the materials to the project site would have created an enormous environmental impact, so Interstate Highway Construction (IHC) worked with a local aggregate supplier to use an existing aggregate and sand pit on the project site. This change had a significant sustainability benefits, eliminating about 1.26 million truck miles, 2,347 tons of CO2 emissions, and almost 21,000 truck trips from state roadways. Mining the aggregates on-site also improved the mix design optimization.

Close communications and teamwork among the design-build team members resulted in many other innovations, including the use of a geogrid, which eliminated 230,000 CY of excavation and embankment from the project scope. This also reduced CO2 by more than 2,100 tons and water demand by almost 10.6 million gallons.

The contractor also recycled the existing asphalt roadway and used it for construction of about 70% of the base course. This had the double benefit of sparing 202,000 tons of new base material, while also diverting the same amount from waste. This change resulted in the elimination of more than 2.1 million truck miles and almost 4,000 tons of CO2 emissions.

Other innovations included the use of automatic plate-load testing to verify the geogrid/base calculations in the field; reduction of dowels and dowel diameters; and the use of a fusion-bonded epoxy on dowel bars and baskets to improve corrosion resistance.

Over the span of 14 months, the contractor’s crews removed and replaced 20 miles of outdated pavement, dirt, drainage and utilities. The complete 27-month project duration included design, construction, acquiring remaining right of way, working with 17 utility companies and Union Pacific Railroad. Despite a delayed start to the project, the the reconstruction of this important roadway under budget and almost 30 days ahead of schedule.