Lewiston Hill project wins national asphalt paving award

The recent U.S. 95 Lewiston Hill reconstruction project has received a National Asphalt Pavement Association (NAPA) award. Knife River Construction, the project’s prime contractor, won the award for paving by producing a pavement nearly twice as smooth as the allowable standard for initial quality.

The project used 112,000 tons of Superpave HMA (Hot-Mix Asphalt) plantmix pavement, and was completed in 99 days rather than the 120 scheduled.

The award will be presented Feb. 10, 2016, to Knife River during the NAPA annual meeting in La Quinta, California.

Smoother pavements generally produce more satisfied road users and a decrease in fuel consumption and vehicle-maintenance costs. Pavements that are initially built smoother generally remain smoother over time and provide a longer service life. A smoother pavement is also highly correlated to traction and control through greater contact between the tires and the road surface.

“Crews not only completed the project ahead of the initial schedule, but kept traffic moving with minor interference,” said ITD Resident Engineer Joe Schacher. “This project is a good example of how it should be done. The roadway is the smoothest paving project I've been involved with since I became resident engineer 12 years ago.”

Resurfacing of a five-mile stretch of U.S. 95 on Lewiston Hill, carrying 10,000 vehicles per day, began in mid-May and ended in early September. Numerous maintenance projects have been performed in the past on the original pavement, placed in 1976. Those included overlays, plantmix seals and seal coats. However, these surface treatments have proven insufficient to keep the highway in good condition. The reconstruction is expected to extend the life of the road by approximately 20 years.

Work on this $11.5 million project involved a mill-and-inlay at depths ranging from two to five inches, CRABS (Cement Recycled Asphalt Base Stabilization) treatment at the top of Lewiston Hill, repairing soft spots near the Port of Entry at the top of the hill, and replacing median barrier and guardrail on the highway.

“This project has the size, complexity, material quality, and smoothness to be on a national stage,” said Knife River Asphalt Operations Manager Josh Smith. “While Knife River's Idaho Division has received honors for many projects through NAPA, I believe this project to be the finest.”

To minimize the impact to drivers, the contractor used a six-day workweek,working 20 hours per day, Monday through Saturday, to complete the project as quickly as possible.

The project achieved an IRI (International Roughness Index) of less than 35 (<35), a significant measure for initial pavement smoothness.

“We typically specify that the contractor meet or exceed the highest quality on a new pavement, which we call Schedule I, and it ranges from six to seven inches per tenth mile,” Schacher said. “Knife River exceeded this requirement with many sections below four inches per tenth mile.”

"Knife River and ITD worked diligently to produce a high-quality project," said Project Manager Paula Pintaur. "This effort resulted in a high-quality, smooth surface that exceeded the ridability of any previous project constructed in District 2."




Published 12-11-15