(Silver Award) Douglas County Concrete Pavement Preservation Program, Highlands Ranch, Colo.
Contractors: Villalobos Concrete Company* | Chato’s Concrete, LLC* | Interstate Improvement, Inc.*
Owner/Engineer: Douglas County, Colo.
When the 22,000-acre, master-planned community of Highlands Ranch, Colo., was founded in 1981, arterial roads throughout the community were paved with concrete, with most of the pavement placed directly on clay subgrade.
As the roads reached the end of their expected life, Douglas County officials looked for a cost-effective solution to repair the roads that had a range of problems – broken and shifted panels, joint separation, transverse joint faulting and cracking.
After an assessment of the roads, county engineers determined that a variety of factors contributed to the movement that was causing the panels to break, separate and crack. The 7.5-inch thick pavement was originally built when the volume of traffic and speeds were lower, and the pavement was built without dowel bars to transfer the loads.
Grinding alone could not address all of the issues, so the contracts for the pavement preservation included repair or replacement of panels as needed, as well as resealing joints. The contractual grinding specs were to meet a Half-car Roughness Index (HRI) specification of less than or equal to 150 in. per mile at a maximum grind depth of 0.5 in.
If the concrete pavement smoothness could not meet this specification, then the contractor had to meet a HRI percent improvement of 50 percent or greater per segment per travel lane. If the pavement already had an HRI of less than or equal to 150 inches per mile, the contractor had to meet an HRI of less than or equal to 80 inches per mile without exceeding the 0.5 in. maximum grind depth.
Lessons learned in the first year of the four-year project were applied to subsequent years to address resident concerns, including phasing of lane closures, noise management, and communication with neighboring residents and businesses.
The four-year program included multiple contracts and contractors, and in all, resulted in the improvement of 155 lane-miles of concrete pavement. The pavement grinding was the largest concrete pavement such effort to date in Colorado. As a result of this project, the pavement life is expected to be extended by up to 20 years. The project also has provided the community with a much smoother road, increased skid resistance, and a quieter pavements.
(Gold Award) State Highway 52 CPR Project, Winneshiek County, Iowa
Contractors: Wicks Construction Inc. | Iowa Civil Contracting, Inc.
Owner: Iowa Department of Transportation
Engineer: WHKS & Co.
The majestic hills of Northeast Iowa are a phenomenally beautiful attraction for the region’s tourists, especially in the fall of the year. The problems of a distressed highway running through this area can detract from the beautiful landscape and wreak havoc with visitors and residents. Not only is the pavement smoothness and noise an issue, but another challenge is how to solve those issues with the least possible impact on traffic.
This was the problem the Iowa DOT faced near Decorah, Iowa, and the owner addressed the issues with an effective patch and grind project that also included partial-depth repairs, full-depth repairs, shoulder retrofits, dowel bar retrofit, diamond grinding, and joint resealing.
The prime contractor, a joint venture between Wicks Construction* and Iowa Civil Contracting, was up to the task, even when the scope of the work increased after letting.
After the project was under contract, the Iowa DOT and Wicks Construction/Iowa Civil Contracting discovered additional pavement restoration would be needed. This resulted in about 50 change orders, which added $2.5M to the original $6.2M contract. Full-depth patching figures doubled and partial-depth repairs increased almost 13 times the original square yardage.
Along with the challenge of increased work, the project still needed to be completed under traffic. Direct detour routes would have been impractical, because the estimated out-of-distance travel for a detour would have added 20 miles to a motorist’s trip.
Fortunately, CPR with diamond grinding expedited project completion and opening to traffic in the shortest possible time. Now, tourists and residents not only have a scenic area to enjoy—they also can do so while traveling on a roadway that is in good condition, and features low noise, adequate friction, and a smooth ride.
* ACPA Member.