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📅 Tue August 19, 2014 - Southeast Edition
Eric Olson - CEG CORRESPONDENT
One of the Tennessee River’s major hydroelectric dams in eastern Tennessee is under construction that is designed to greatly improve highway traffic in the area.
The Fort Loudoun Dam is located on the river at Lenoir City, southwest of Knoxville. Built by the Tennessee Valley Authority (TVA) during World War II, the dam has provided continuous electricity and flood control on the Tennessee since its completion in 1943.
The 4,190-ft. (1,277.1 m) long, 122-ft. (37.2 m) high dam created Fort Loudoun Lake, from which the dam gets its power. Water from the nearby Tellico Reservoir also helps operate the dam.
One Bridge to Be Demolished
U.S. Highway 321/Tennessee Route 73 currently carries vehicle traffic over the dam via the J. Carmichael Greer Bridge.
However, U.S. 321/Tenn. 73 is only two lanes wide over the 50-year-old bridge, as well as the approaches to it and two other bridges nearby. The rest of the highway for miles in each direction is made up of four lanes.
Therefore, as part of the entire project, the Greer Bridge is slated to be demolished. The highway will be diverted just south of the dam and across a new four-lane bridge over the river about 2,000 ft. (609.6) downstream of the dam.
According to the Tennessee DOT, the fact that the Greer Bridge was only designed for two lanes of vehicle traffic was not the only reason that it is being dismantled.
“From at least the 1990s, TVA has wanted to remove bridges from on top of its dams to provide easier and safer access for workers to perform maintenance to the dams,” said Mark Nagi, community relations officer of TDOT’s Region 1.
A Complex Project
The multi-faceted road project involves no structural work to the dam itself, only the dismantling of the bridge over it. In addition, a new two-lane span over the nearby Tellico Canal is being built next to an existing two-lane bridge just to the south of the dam; and a short four-lane bridge for the highway has been completed to the dam’s north over the Norfolk Southern Railroad in Lenoir City.
Nagi said that the demolition of the old Greer Bridge over the dam was decided early on in the overall project’s development because the TVA didn’t want to have to replace or widen the bridge. In addition, over the years, traffic often could not cross the bridge when maintenance was going on — a fact that was very upsetting to motorists in the area.
The project also includes widening U.S. 321 to four lanes from U.S. 11 in Lenoir City, about a mile north of the dam, to just east of the Tellico Canal on the south end. This portion of U.S. 321 is the only part of the highway that is not currently four lanes from Maryville in the east to Interstate 40 in the west, according to the TDOT.
Increased traffic on U.S. 321 over the last several years has made it essential that the entire route through the area be at least four lanes. The highway helps bring visitors to and from I-40 and nearby I-75 through Lenoir City and Maryville to the Great Smoky Mountains, the most visited national park in the country.
Halfway Through the Work
The project began in July 2012 and is currently budgeted at $69.6 million. The estimated completion date, according to Nagi, is June 2016. The general contractor overseeing the work is Charles Blalock and Sons Construction in Sevierville, Tenn.
The small bridge over the railroad north of the river was the first part of the project to be completed. A concrete I-beam bridge about 180 ft. (54.9 m) long, its four lanes include a turn lane in the middle and 10-ft. (3 m) shoulders on each side.
One abutment is completed on the new bridge over the Tennessee River just below the dam, and the fill is being placed for the second. In addition, construction on one of its piers had begun by that time. The span is a 1,400-ft. (426.7 m) long welded steel girder bridge.
The third bridge, over the Tellico Canal (which connects Fort Loudoun Lake and the Tellico Reservoir), also makes use of a welded steel girder and is 1,071 ft. (326.4 m) long. It is designed to be only two lanes wide and will bring southbound U.S. 321 traffic across the canal and the Tellico Parkway — right next to the existing two-lane northbound bridge of U.S. 321.
Both abutments and two of the piers of the third bridge are finished, with two other piers about halfway complete, Nagi said.
Widening efforts on U.S. 321 leading to the different bridges also are moving along on schedule.
Just under 1 million cu. yds. (746,554.9 cu m) of borrow material has been required on the Fort Loudoun Dam project, of which about two-thirds has been placed.
Nagi said the work was 50 percent complete in mid July, precisely at the scheduled halfway point of the project.
Few Problems Encountered
He also said that the only problems encountered have been fairly minor for a project of this complexity.
For instance, it was discovered that some additional land-use permits from TVA and environmental permits associated with those permits were needed before construction could begin on the piers for the Tennessee River bridge, Nagi said. TDOT worked with the contractor, TVA and environmental agencies to obtain those permits, he said.
Also, a value engineering change proposal (VECP) had to be submitted by the contractor to change the footings on the Tellico Canal bridge from spread footing on a seal to a drilled-shaft design. Nagi said this eliminated the need to drill and blast immediately next to the existing bridge footing and created less of an environmental impact.
There also has been very little traffic disruption caused by the project — on both the road and on the water. Nagi said that there have only been a few nights when traffic lanes have been reduced for minor adjustments to the road. A “wake-free” zone has been placed in the canal though the work zone, but that has proven to be very little interference for boaters.
Blalock and Sons has performed the majority of the work on the Fort Loudon Dam project, including all of the bridge work and most of the earthwork. The major subcontractor on the venture is Patty Construction Inc. in Lenoir City.