The Asphalt Pavement Alliance (APA) awarded the Montana Department of Transportation (MDT) with a 2005 Perpetual Pavement Award for a section of I-90 from Laurel to Billings.
The award will be presented at a special ceremony during the International Conference on Perpetual Pavement in Columbus, OH, Sept. 14, 2006.
MDT will receive an engraved crystal obelisk and a plaque and will have its name and project added to a permanent plaque, which is kept at the National Center for Asphalt Technology (NCAT) in Auburn, AL.
To qualify for this prestigious award, a pavement must meet strict criteria and demonstrate hot-mix asphalt’s (HMA’s) long-life characteristics, excellence in design, quality in construction, and value to the traveling public.
It also must have been constructed at least 35 years ago. Engineers at NCAT evaluated the nominations and a panel of industry experts validated the winners.
Montana’s award-winning pavement is a 6-mi. (9.7 km) section of I-90, from milepost 439 to 445, which was opened to traffic in 1961.
The road was built with 13.2 in. of subbase, 11.4 in. of crushed stone base and 4.2 in. of HMA.
Some sections of the road received an overlay of 2.4 in. of HMA and .75 in. of open-graded friction course in 1984.
In 2001, 3.6 in. of the road were milled and replaced with a 3.6-in. Superpave HMA overlay.
The road carries an average daily traffic count of 24,640 vehicles and has an average 1,560 daily ESALs (equivalent single axle loads), which is one of the highest daily ESAL loadings in the state.
Despite this heavy use, the road has held up well and MDT does not anticipate the need for any major repair or reconstruction soon.
“We believe there are four reasons why this road has lasted so long: good subgrade, high-quality paving materials, well-timed maintenance schedule and a permanent weigh station located on the project,” commented Dan Hill, pavement design engineer of MDT.
“During the time that this road was built, we were getting very good asphalt binder. The base course was of crushed Yellowstone River gravel, and this was also used in the HMA mix. The rock adheres very well to the binder.”
MDT invests heavily in its pavement preservation program, which also helps to maintain the roads in excellent condition, he said. The permanent vehicle weigh station located immediately west of this road section discourages trucks from running overweight on the road.
“This road is simply astounding,” said Loran Frazier, MDT chief engineer. “It is obvious we did something right 40-plus years ago when this project was constructed. The quality of material and the contractor’s methods made this project a success. We should learn from it and replicate the practices for the future.”
The Asphalt Pavement Alliance is a coalition of the National Asphalt Pavement Association, the Asphalt Institute, and the State Asphalt Pavement Associations.