Short haul on U.S. 425 wins asphalt award

47-year-old surface outdoes initial design requirements

Monday, May 12, 2014

A remote 2.3-mile section of U.S. 425 in Lincoln County has stood the test of time.

Built 47 years ago, the section a little north of the Drew County border on a stretch connecting Star City and Monticello never has had a structural failure, has received minimal maintenance during that time and remains a sturdy surface for the traffic that uses it -- all factors that helped it win one of eight national Perpetual Pavement Awards for 2013.

The awards were announced last month by the Asphalt Pavement Alliance, a consortium of pavement associations dedicating to promoting asphalt pavements.

"One of the keys to sustainability is long life," Michael J. Kvach, the organization's executive director, said in announcing the award recipients. "Asphalt roads can be engineered to last indefinitely with only routine maintenance and periodic surface renewal."

That means significantly reduced life-cycle costs because the pavement doesn't have to undergo a more extensive and expensive reconstruction, traffic delays are reduced because smaller maintenance work requires shorter lane closures and reduced material resources over the life of the road, he said.

The award is the fourth one in a row received by the Arkansas Highway and Transportation Department.

The task of identifying the award-winning section of asphalt -- which amounts to less than 14 thousandths of 1 percent of the 16,398 miles on the state highway system -- fell to Luke Stovall, a 28-year-old civil engineer in the department's asset management section.

The pavement hunter used the skills of a historian in combing the department's databases and microfilm archives.

It isn't that the highway system doesn't have a plethora of high-quality, long-lasting roads, but finding one with adequate documentation that met the requirements of the award "took a lot of research," Stovall said. For instance, some of the requirements of the award included the section being at least 35 years old with an average interval between resurfacing of no less than 12 years.

He researched five other highway sections before scoring on the U.S. 425 section.

The section was originally built in 1966 as Arkansas 81 by Southeast Construction Co. of Pine Bluff. It consisted of two 12-foot lanes and two 8-foot shoulders. Stovall was unable to find the cost of the contract for the project.

The Arkansas Highway Commission re-designated it as U.S. 425 in 1989.

It begins south of Pine Bluff at Interstate 530 in Pine Bluff, continues south into Louisiana and crosses the Mississippi River before terminating in Natchez, Miss. In Louisiana, it routes traffic toward Monroe and provides access to Interstate 20.

In Arkansas, south of Pine Bluff, the department said, U.S. 425 serves as the primary access to Monticello and for the extensive logging and agricultural interests in the region.

The roadway section that was nominated was built in four distinct layers: a subgrade of compacted dirt, a layer of rock known as the base, an asphalt binder and an asphalt surface. The base ranged from 6 inches to 7 inches deep, the binder from 2 to 3 1/2 inches and the surface layer was 1 1/2 inches.

The section was designed to withstand an average daily traffic count of 1,700 vehicles per day with the percentage of trucks at 18 percent. The average daily traffic count now is 3,600, 112 percent more than its designed capacity. Truck traffic now represents 18 percent of the average daily traffic, 23 percent higher than for what it was designed.

Building roads in southeast Arkansas always has been problematic because of the heavy clay content of the soil, which is the foundation of all highways. Typically, the clay has to be bolstered with cement to stabilize it, or dirt has to be trucked in from elsewhere, Stovall said.

"The performance of this road is especially exceptional considering the underlying native soil," he wrote in the nomination letter.

The section has undergone two repairs since it was built for an average resurfacing interval of 21 years.

It was part of a 10-mile project in 1987 that gave the section an asphalt overlay 1-inch deep for $365,388, or $36,538.80 per mile. In 2008, it received a 2-inch overlay for $437,953, or $191,245.85 per mile, according to Stovall.

"The original pavement structure of this section of U.S. 425 was robust enough to withstand traffic loading above and beyond its original design purpose and then required minimal surface treatments to prolong its life," Stovall said. "The pavement is still performing very well."

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US 425

Metro on 05/12/2014