U.S. Route 129 in Tennessee

U.S. Route 129 (US 129) is a north–south United States highway that runs for 52.8 mi in East Tennessee, from the North Carolina state line, near Tapoco, to Knoxville. In Tennessee, the highway is completely overlapped by unsigned (except for mileposts) State Route 115 (SR 115). In the Greater Knoxville area, US 129 serves as a six-lane controlled-access highway known as Alcoa Highway.

"Tail of the Dragon" and Calderwood Highway
U.S. 129 enters Tennessee from North Carolina at through the Deals Gap mountain pass through the western fringes of the Great Smoky Mountains. Immediately within Blount County, the highway twists and turns, roughly following the natural topography of the mountains. This section is known as the "Tail of the Dragon" (or simply "The Dragon") due to its extremely sharp and tight curves, and roughly forms the boundary between the Great Smoky Mountains National Park to the east and the Cherokee National Forest to the west. The "Tail of the Dragon" is very popular with tourists and enthusiasts of motorcycles and sports cars. After several miles, the highway gradually straightens out, and starts running along the banks of the Little Tennessee River. Here the road becomes known as "Calderwood Highway". The highway then shifts into an east-west alignment and has an intersection with the western terminus of the Foothills Parkway before passing by Chilhowee Dam and going through the Tallassee community. US 129 then turns north and briefly enters Monroe County where it has an intersection with the eastern terminus of SR 72. It then reenters Blount County and passes through additional woodlands, before intersecting with SR 336 in the Lanier community.

US 129 continues northeast over the next several miles through a mix of farmland and residential neighborhoods to Clover Hill, where it becomes concurrent with US 411. The two routes proceed northeast as a five-lane undivided highway with a center turn lane to enter the city of Maryville. Passing initially through mostly residential areas, the highways have an intersection with the southern terminus of SR 335 (William Blount Drive). The two highways then pass though additional neighborhoods and a commercial area, before reaching a directional T interchange, where US 129 separates from US 411. Bypassing downtown Maryville on the west side, US 129 becomes a divided four-lane highway here known as US 129 Bypass as it passes by Foothills Mall and has intersections with US 321 (Lamar Alexander Boulevard), Foothills Mall Drive (unsigned SR 446), and Foch Street before crossing into the neighboring town of Alcoa. US 129 then has an interchange with Midsettlements Road and Bessemer Street before reaching an intersection with Louisville Road, which provides access to the neighboring town of Louisville. The highway then has an at-grade railroad crossing before coming to a directional-T interchange with SR 35 (N Hall Road), which also provides access to downtown Maryville.

Alcoa Highway
At the interchange with SR 35, US 129 becomes a divided highway currently in the process of being upgraded into a controlled-access highway. Initially known as Airport Highway the highway has an interchange first with a connector to SR 335 (Hunt Road) and then a connector to McGhee Tyson Airport. It then becomes known as Alcoa Highway, a name that it keeps all the way to its northern end. The highway then passes through a major business district before having an intersection with Airbase Road (SR 429) and coming to a cloverleaf interchange with the Pellissippi Parkway (I-140 westbound, SR 162 southbound). The stretch between the airport and Pellissippi Parkway is often considered dangerous and even deadly due to the amount of traffic and crashes on the highway. Alcoa Highway continues through suburban areas before having an intersection with SR 333 (Topside Road) before leaving Alcoa. It then crosses a bridge over the Little River to enter Knox County.

Immediately within the city limits of Knoxville, the route has an interchange with SR 168 (Governor John Sevier Highway) a short distance later east of the Fort Loudoun Lake impoundment of the Tennessee River. It then passes through a wooded area, crossing an impoundment of the lake, and then becomes a freeway once again. Expanding to six lanes, the highway gains frontage roads, which provide access to a dogbone interchange with Maloney Road, and partial interchange with Montlake Drive. The road then reduces to four lanes, passing adjacent to the east side of the river again, before reaching a trumpet interchange with Cherokee Trail, expanding back to six lanes and once again becoming a freeway. US 129 then crosses the Tennessee River on the J. E. Buck Karnes Bridge. Immediately on the other side of the river, the highway has interchanges with US 11/US 70/SR 158 (Neyland Drive) and Kingston Pike, and runs along the western edge of The University of Tennessee. US 129 then crosses a series of railroads and surface streets on a long viaduct through industrial areas before coming reaching its northern terminus at an interchange with I-40.

Early history


In 1935, the American Association of State Highway Officials (AASHO) approved an extension of US 129 into Tennessee. The highway followed SR 72 from the state line to US 411 near Vonore. The route then remained concurrent with this route and SR 33 to Maryville, where US 411 split off, heading toward Sevierville. US 129 would then follow SR 33 to US 11/70 in Knoxville. This route crossed the Tennessee River on the Henley Street Bridge in Knoxville, which was joined by US 441 in 1951. By 1940, AASHTO approved rerouting US 129 onto SR 115 between Tallassee and Maryville. As part of the construction of Chilhowee Dam between 1955 and 1957, a new higher alignment was constructed between Tabcat Creek and the dam. Today, the old route is largely submerged, but is sometimes visible when the water level is low.

The Alcoa Highway portion of US 129 was first constructed and completed as a two-lane roadway from Knoxville to Blount County in 1939 to provide access to the then recently opened McGhee Tyson Airport. Initially, this route only carried the SR 115 designation, and in 1961, AASHO approved rerouting US 129 onto Alcoa Highway. They also rejected a request by Tennessee to renumber the old US 129 alignment along SR 33 to US 129 Alternate. US 129's bridge over the Tennessee River in Knoxville was completed in 1935, and was named after James Ernest Karnes (a.k.a. J. E. "Buck" Karnes), a Knoxville recipient of the Medal of Honor. On November 29, 1963, the final project to widen Alcoa Highway into a four-lane median-divided facility between I-40 and McGhee Tyson Airport was completed and dedicated by Tennessee Governor Frank G. Clement, U.S. Senator Herbert S. Walters, and Congressman Howard Baker. Several upgrades improving mobility were constructed on the Knoxville-Knox County section of Alcoa Highway, including replacements of at-grade intersections with interchanges at the University of Tennessee Medical Center (UTMC) and John Sevier Highway in the mid-1970s and mid-1980s respectively.

Major projects
Increasing congestion on Alcoa Highway in Knoxville prompted pushes from residents to form a neighborhood group Make Alcoa a Safe Highway (MASH) in the early 1980s, seeking to address concerns of safety on the highway. In 1986, MASH issued a report with immediate request and short and long-term range plans. Several of the recommendations were established such as a ban of parking on the US 129's right-of-way, speed limit enforcement, and highway lighting. Major planning by the Tennessee Department of Transportation (TDOT) in the 1980s and 1990s recommended median crossing closures, new overpass structures, and the widening into a six-lane facility.

The construction of the Pellissippi Parkway from Oak Ridge to Alcoa required the construction of a cloverleaf interchange at US 129, which was completed in the early 1990s. Around the same time, the City of Knoxville installed lighting along the highway from the Little River north to the UTMC following annexation of the US 129 right-of-way and selected neighboring commercial and residential land-uses. Improvements were made to the US 129 interchange at I-40 and the "Buck" Karnes bridge was replaced with a new six-lane structure by the early 2000s. By 2000, TDOT began property acquisitions for the planned expansions of Alcoa Highway between I-40 and the Little River.

In 2014, TDOT announced plans for improvements to the Alcoa Highway section of US 129 from I-40 to McGhee Tyson Airport in Blount County. The massive project, consisting of seven phases, called for the conversion of Alcoa Highway from a non-access-controlled highway into a full controlled-access highway (freeway). The overall project was given an initial cost of more than $233 million. The first phase of the project to begin was the Maloney Road to Woodson Drive phase in South Knoxville, with contract bidding opening in February 2016. Construction work on the Maloney to Woodson phase of the Alcoa Highway improvement project began in June of the same year. This section would be mostly complete by the fall of 2021, when new revisions for an access roadway to the Montlake Drive interchange were issued, expecting to be finished in the winter 2022. The next phase that will construct the Alcoa Highway between Woodson Drive to Cherokee Trail was started in July 2023 and is expected to be completed by Fall 2027.

State Route 115
State Route 115 (SR 115) is the hidden state route that overlaps the entire route of US 129 in the state of Tennessee. The highway is 52.8 miles (85 km) long and is located entirely in East Tennessee. It begins in Blount County and ends in Knox County. It is completely unsigned, with the exception of mileposts, with the highway being solely signed as US 129.