Then, 11,200 tons of HMA was placed as an inch and a half intermediate course over the entire stretch of road late last fall. A Cedarapids 551 and a Vogele paver were used to lay the base and intermediate courses. An Ingersoll Rand 110 breakdown roller, a Bomag pneumatic roller, and a Sakai static finishing roller were used to achieve density specifications.
Earlier this year, Norris paving crews returned to place two 1 1/4-inch mats to finish the project. They used a new Low Tech 195 paver with a Roadtec Shuttle Buggy to lay 19,500 tons of asphalt in the final two lifts.
All the HMA used on the project was produced at Norris' portable Gencor 400-tph plant, and mix design had to meet Iowa DOT gyratory void standards and be comprised of at least 45 percent crushed aggregate measuring a 1/2 to 3/4 inches in size.
Dave Paulson, Carroll County engineer, says an additional inch of HMA was requested following completion of the intermediate course in order to achieve approximately eight inches of new road surfacing when the project was completed.
"That had always been a target we wanted to hit in the reconstruction of this road, due to the potential high truck traffic expected," Paulson says.
As primary contractor, Norris began work on the project in mid-August 2003, and completed initial paving by November, and then returned this spring to place the final two top lifts.
Norris had 130 construction days built into the original proposal, and completed the project in 70 days, receiving a $23,000 smoothness bonus, with a 97.26 percentage smoothness rating on the project.