Traffic drives expansion

Tennessee’s U.S. 79 requires more than 80,000 tons of asphalt

By Candy McCampbell

More car and truck traffic on the two-lane U.S. Hwy. 79 in West Tennessee is driving a three-year, $13.6 million expansion of the highway to five lanes.

J.R. Hayes Construction Co. Inc. of Paris, Tenn., is the contractor for the job, which runs from the U.S. Hwy. 79 intersection with Sydnor Road/Winston Road northwest to McKenzie, Tenn. The 3-mi stretch includes the highway expansion, utility relocation, erosion control and seeding and sodding, says Matt Hayes, project manager.

“The existing road is 22 ft wide, and the new one is 84 ft between the faces of the curbs,” he says. There are no curbs on the existing highway.

The new road has a base of 10 in. of gravel, or about 100,000 tons, topped by 4 lifts of asphalt that total 9.75 in. The job will require more than 80,000 tons of asphalt.

The road falls about 10 in. from the center line to the curb to drain rainwater.

Delta Contracting Co. of Humboldt, Tenn., is supplying the asphalt from its Paris operation about 20 mi up the highway, says Austin Bateman, Delta area manager. The company uses 18 trucks to run an average 80 loads a day for the paving.

The new road is basically following the center line of the existing road, with a few exceptions such as a small curve to go around a church and cemetery, Hayes says. For that reason, there’s not a lot of grading involved other than the road widening itself.

Workers are moving about 220,000 cu yds of dirt, and about 100,000 cu yds are being hauled to the site.

Some of the existing road stays in place but some of the top layer is being milled up and recycled for use in the new pavement, part of a trend nationally to reuse existing gravel and liquid asphalt that covers it.

“Liquid asphalt is so expensive now,” so contractors like to save and reuse all they can, Hayes says.

The price of asphalt has more than doubled, from $189.58 a ton in 2005 to $401.54 a ton in May, according to the Tennessee Department of Transportation.

TDOT allows use of recycled asphalt pavement on all its projects, says Julie A. Oaks, TDOT information officer. Asphalt pavement reuse is both a way to recycle resources and to keep prices lower, Oaks adds.

“RAP is allowed in different asphalt mixes at different rates, but the rates are consistent across the state,” she says.

Surface mixes can have up to 10% to 15% RAP, but the proportion of RAP can go up to 30% in below-surface structural mixes that are not exposed to weather, she says.

Costs are even more important to states now, so TDOT is watching the numbers, Oaks says.

The choice of asphalt or concrete for a highway job is usually made based on cost estimates made when the project is let to contract, Oaks says.

“Typically asphalt has a lower initial cost, but with the recent significant price increases in petroleum products the cost of asphalt and concrete are closer now than ever,” she says.

The monitoring will continue as prices change, Oaks says.

The new highway curbs are concrete, poured with a slip-form paver, and have only nine side roads to break the line, Hayes says. The curbs are being used because of a heavier population than rural areas and the need for less right-of-way, he says.

The highway widening also means moving water and sewer lines, as well as powerline relocation and pole replacement the entire length of the project. The city of McKenzie is installing new water and sewer lines and a new pumping station, while the Carroll County Electric Department is removing the old wood poles and replacing them with new galvanized metal poles.

Storm-sewer work involves laying about 19,000 ft of pipe and installing more than 100 storm-sewer structures, catch basins and manholes.

The biggest challenge on this project is “making sure each (contractor or subcontractor) has their job done ahead of the other one so you don’t have to stop and wait on somebody,” Hayes says.

Started in July 2007, the job is due for completion in October 2009 and is currently ahead of schedule. J.R. Hayes Construction has about 20 employees onsite and subs have another 20 to 30.

U.S. Hwy. 79 runs over relatively flat land, with a few small hills and no major waterway or railway crossings. There are three box culverts running over small, usually dry streams that drain the area during heavy rains.

Two of the box culverts are precast and the third is poured in place.

Installation of the box culverts necessitates traffic lane shifts as they are placed and paved over, Hayes says.

Otherwise, the plan is to build one side of the new highway and shift all traffic to it while the other side is under construction to prevent traffic jams on a road that averaged more than 11,000 vehicles a day last year.

“We encroach one wetland area minimally at one end of the job,” Hayes says. Mitigation work includes some stream relocation and planting about 1,000 trees, as well as temporary and permanent seeding.

Some of the trees have been planted, says Cathy Griffin, president of Interstate Landscaping of Mississippi in Falkner, Miss. The varieties include river birch, maple, ash, oak, black gum and cypress, all 18 to 24 in. tall.

Her crews are putting down 16,000 sq ft of erosion control blanket, 80,000 sq yds of sod, 200,000 sq ft of temporary seeding and 133,000 sq ft of permanent seeding.