MASSIVE MOVEMENT
U.S. Highway 27 construction reshaping city’s landscape
One year down, two to go. Work crews in February began cutting into the earth on either side of U.S. Highway 27 in a project to widen and improve the busy artery between Signal Mountain Road and the Olgiati Bridge. The work is supposed to be finished in December 2014.
Here are some fast facts about the U.S. 27 project from the Tennessee Department of Transportation:
Workers are adding northbound and southbound lanes, building 34 retaining walls and six bridges and reconstructing interchanges at Signal Mountain Road, Dayton Boulevard and Manufacturers Road. The $102 million project is the department’s biggest ever in Southeast Tennessee.
On average, 73,000 vehicles per day funnel through the work area, hemmed in by 11,000 linear feet of temporary concrete barrier walls.
The project area is 1.62 miles long and the maximum right-of-way width (at the Dayton Boulevard exit) is 553 feet. Right of way for four southbound and five northbound lanes is 148 feet. Paving all that will use 80,000 tons of hot-mix asphalt.
Six large overhead signs will span the roadway to carry traffic and other important information for commuters. At night, drivers will pass under 44 roadway lights. Of those, 20 will be 100 feet tall.
The job will involve 34 different subcontractors before it’s completed. About 100 workers are onsite any given day and about 20 at night, overseen by 12 to 17 regular inspectors.
When the sun goes down, giant light stands with four to six bulbs each illuminate the work area. Each bulb puts out 150,000 lumens, or 12,000 candlepower.
Best guess of man-hours worked to date is about 300,000. So far, there have been no serious injuries requiring significant medical attention.
Cost of one hard hat: $6-$12 (they’re cheaper in bulk).
When workers need a bathroom break, they can visit any one of 12 to 15 Port-APotties, which rent for $45 to $50 per week.
The amount of earth moved so far — about 130,000 cubic yards — is just 22 percent of the 600,000 cubic yards to be taken from the site and disposed of elsewhere — some at other TDOT projects. Earth containing acidforming iron pyrite is taken to a permitted landfill where it can be disposed of without harming the environment.
The project’s six new bridges — U.S. 27 over the railroad tracks, Manning Street, Elmwood Drive, the southbound Dayton Boulevard entrance ramp, the northbound Dayton Boulevard and Signal Mountain Road exit ramps — will use eight miles of steel piling.
Trucks, earthmovers and other equipment drink 800 gallons of diesel fuel per day. The project has bought 176,000 gallons of diesel to date.
Vertical pillars for the 14,400 linear feet of concrete retaining walls are custom made for their exact position in each wall. The top of the tallest retaining wall — atop two other walls — will be 120 feet above the highway.
Plans call for using 380,000 board feet of 4-by-6-inch oak behind the concrete facing of the retaining walls.
Sixteen walls will use soil anchors, cable bundles sunk 100 feet into the earth and grouted in place. Workers have installed more than 2,000 anchors totaling 200,000 linear feet.
Final fact: Because initial planning for this project began in the 1990s, when the United States was under a mandate to switch to metric measurements, TDOT’s Flynn had to recalculate many of the weights and measures on this list from metric to standard units.