TDOT’s Interstate 81 Honored by APA

Thu April 14, 2005 - Southeast Edition

The Tennessee Department of Transportation has won a 2004 Perpetual Pavement Award for a section of Interstate 81 in Washington and Sullivan Counties from the Asphalt Pavement Alliance (APA).

The award will be presented by Jack Lettiere, Jr., 2005 president of the American Association of State Highway and Transportation Officials, at a May 18 ceremony at the National Center for Asphalt Technology (NCAT) at Auburn University in Auburn, AL.

To qualify for this award, a pavement must meet strict criteria and demonstrate Hot Mix Asphalt’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.

“We take great pride in this achievement,” said TDOT Commissioner Gerald Nicely. “Our materials and tests division team strives to utilize the latest technology to put the best product available on our roadways.”

The award-winning pavement was an eight-mile section of Interstate 81 in the northeastern corner of Tennessee, mile marker 11.56 to 19.71. In 1969, when the road opened, the Average Daily Traffic (ADT) was 8,400 vehicles per day. In 2002, the ADT was approximately 39,900 vehicles per day. Since its construction, this stretch of interstate has withstood an estimated 29 million ESALs (Equivalent Single Axle Loads) without any sign of structural failure.

The pavement was originally constructed of 8 in. of crushed stone base, 10.5 in. of bituminous base, 1 in. of binder course and 1 in. of surface course. The state overlaid one three-mile section with a 1.25-in. layer of Hot Mix Asphalt (HMA) in 1977 and spot-milled and overlaid the same section with a 3.25-in. HMA layer in 2002. A different five-mile section was milled and overlaid with 2.75 in. of HMA in 1989.

“I think there are several reasons this road has held up so well,” said Gary Head, civil engineering director of TDOT’s materials and tests division. “First, for its time and day, it had a very good crushed stone base – eight inches of limestone. A good base is vital to a good roadway.”

The design also used a large stone base, which served as a conduit to allow water to get out of the pavement.

“This stone mix had a lot of stone-to-stone contact, which is something that the industry is getting back to,” he added.

Finally, TDOT successfully designed the pavement to handle the loads it would carry in the future.

“For this road, we anticipated the right usage category and designed for it,” Head said.

“Even though this pavement has been punished by more than 35 years of use, motorists are still using the original pavement structure,” said Larry O’Donnell, APA co-chairman. “The extraordinary performance of this pavement is worthy of attention.”

“Perpetual Pavement is an industry standard which is extremely well represented by this highway,” added Luke Stango, APA co-chairman. “Long life, durability and exceptional performance are hallmarks of Hot Mix Asphalt. This pavement is testimony to high-performance asphalt as a marriage of excellent design and quality construction.”

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