Silver Award – County Road T-26 Marble Rock, Floyd County, IA
Contractor: Cedar Valley Corporation*
Owner/Engineer: Floyd County, Iowa
A challenging work schedule under any circumstances can make pavement construction challenging, by when Cedar Valley Corporation discovered about 41% of a 6.05 mile reconstruction project area required substantial subgrade repair, crews responded with creative solutions based on expert decision-making, hard work and the use of maturity testing to get the job done.
The Iowa County Road T-26 project involved removal and recycling of the existing 9 in.-thick asphalt (which was milled and hauled to an asphalt plant). Tackling the subgrade issues, crews removed 17,893 CY of unsuitable material, then placed about 32,000 SY of geogrid fabric and 34,000 tons of rock. The excavation for the base rock was successfully incorporated into project by widening the proposed shoulders. This eliminated the need to haul material off the project, thus providing fuel savings and also eliminating a potential fugitive dust situation.
The geogrid fabric and rock created an ideal platform on which the contractor then placed 78,662 SY of 8-in. concrete pavement. The new roadway was designed to be paved 22 ft. wide with 5-ft. rock shoulders. Based on the narrow shoulders, CVC chose to place the concrete directly in front of the paving operation by trimming and placing the concrete with one machine. CVC pressed into service an “Iowa Special,” a modified CMI dual-lane trimmer configured with a dumping belt placed over the machine. The machine allowed the crew enough space to set and place dowel baskets directly on the freshly-trimmed grade and just ahead of the paver.
Although the actual project was closed to through traffic, local access had to be maintained, an especially important point as the construction was done during Iowa’s peak harvest season. CVC not only maintained access to 17 residences that lined the road, they also had to provide access to 40 field driveways for local farms. Excellent communication with property owners (advance stockpiling of driveway materials at each property) and the use of maturity testing enabled CVC to balance local access with the need to ensure the pavement was not damaged because of opening too early.
In spite of completing about $628,000 in extra work, DVC successfully completed the project within the 100-day schedule, creating a durable road that will last for many years.
* ACPA member.