Page 6 - May-June 2021 Vol 39 No 1

MORGAN & ROANE COUNTIES By William H. Pate
LARGE Walls in Difficult Terrain

Neel-Schaffer provided engineering Geological Rock Formations, The geological rock formations in
design and construction assistance Complications the area varied throughout the project,
services for multiple retaining walls that mainly from the Cumberland Plateau
were built during a very challenging Acid producing rock (APR) was over-thrust, the Emory River Fault
Tennessee Department of Transportation encountered when the preliminary Complex, and the Rockwood Fault.
(TDOT) project to widen State Route 29 subsurface exploration was completed by These formations made up the structural
near Harriman, Tennessee. engineering firms ARCADIS and S&ME.

State Route 29 (US 27) runs north
and south across Tennessee from
Chattanooga to the Kentucky line.
The road passes through rural and
urban areas and varies from four to
two lanes. The location of this project
passes through steep hills northwest
of Harriman and was a two-lane road
winding its way through the valley along
Little Emory River and Bitter Creek.

Construction began in 2016 and was
completed by January of 2020. The road
was widened from two lanes to four,
from the interchange at State Route 61 to
State Route 328, a distance of 5.31 miles.
Three tiers of 50-foot walls now soar
a total of 150 feet above the roadway,
providing a dramatic, aesthetically
pleasing backdrop and safe haven for the
new four-lane roadway below.
Project Costs

Neel-Schaffer served as a subconsultant
to Charles Blalock Construction &
Sons, Inc., and the project was phase-
constructed in two sections. The first
project let for $62.8 million, with a total
wall cost of $22.7 million. That included
eight cut walls, and one mechanically-
stabilized earth retaining wall. The total
exposed wall surface is 208,846 square
feet. The second project let for $32.9
million, with a total wall cost of $14.2
million. That phase included four cut
retaining walls, with a total exposed wall
surface of 156,792 square feet.
Limited Sight Distances

The existing road was buffered by high
ridges on both sides of the valley and had
problems with limited sight distances,
due to the sharp horizontal curves and
narrow shoulders. This project was a
challenge for several reasons:
• It is in an environmentally sensitive

area
• It required large roadway cuts, and
• TDOT required that traffic be

maintained during the construction.

6 TPW May/June 2021