Interstate 640

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Interstate 640

I-640 highlighted in red
Route information
Auxiliary route of I-40
Maintained by TDOT
Length10.80 mi[1] (17.38 km)
ExistedNovember 12, 1958–present
HistoryCompleted in 1982
NHSEntire route
Major junctions
West end I-40 / I-75 in Knoxville
Major intersections
East end I-40 / US 25W in Knoxville
CountryUnited States
Highway system
SR 477 US 641

Interstate 640 (I-640) is an east–west auxiliary Interstate Highway in Knoxville, Tennessee. It serves as a bypass for I-40 around Downtown Knoxville and is also an alternative route for traffic passing between I-40 and I-75. All trucks carrying hazardous cargo through Knoxville are required to use I-640. It has a total length of 10.80 miles (17.38 km) and runs approximately three miles (4.8 km) north of downtown through the northern neighborhoods of Knoxville.[1]

For its first 3 miles (4.8 km), I-640 has a concurrency with I-75, although exits along this segment are numbered according to the former's mileage. For the rest of its length, the Interstate maintains an unsigned concurrency with U.S. Route 25W (US 25W). Both of these highways were rerouted from their original alignments upon I-640's completion.

The route that is now I-640 was first planned by the city of Knoxville in 1945 and initiated by the Federal Aid Highway Act of 1956, along with most of the Interstate Highway System. Initial construction work began in the early 1960s, and for many years, only two miles (3.2 km) of the highway was open to traffic. Work on the remainder of I-640 began in 1977, and the last section was completed in 1982.

Route description

I-640 westbound at SR 62 (Western Avenue)

I-640 has three lanes in each direction for its entire length, in addition to auxiliary lanes between some interchanges. In 2022, annual average daily traffic (AADT) counts ranged from 70,244 vehicles per day at the highway's eastern terminus to 104,064 vehicles on the western leg.[2][3] Unlike the other Interstate Highways in Knoxville, however, I-640 rarely experiences severe congestion.[3]

I-640 begins west of Downtown Knoxville at a semi-directional T interchange with I-40 and I-75, where the latter continues onto a concurrency with I-640. Along this section, I-640 is treated as the primary route, with exits numbered according to its mileage. Initially heading northwest, the Interstate immediately passes under State Route 169 (SR 169, Middlebrook Pike) without an interchange.[1][4] A short distance beyond this point, the highway turns north and crosses a CSX railroad mainline,[5] intersecting with SR 62 (Western Avenue) in a partial cloverleaf interchange a short distance later. It then veers northeast into the southern fringes of Dutch Valley, running along the northern base of Sharp's Ridge. About 1.5 miles (2.4 km) later, I-640 reaches an unusual three-level combination interchange, commonly known as the Sharp's Gap Interchange, with US 25W (Clinton Highway), I-75, and the northern terminus of I-275. A series of towering radio masts on Sharp's Ridge dominate the view to the south here.[1][4]

I-640 eastbound near the I-75/I-275/US 25W (Sharp's Gap) interchange

At this interchange, I-75 splits off, heading north towards Lexington, Kentucky, and US 25W and SR 9 begin an unsigned concurrency with I-640. Also at this interchange, SR 9 continues onto an unsigned concurrency with US 25W north to Clinton.[1][4] The highway then shifts slightly east-northeast and, a few miles later, has a partial cloverleaf interchange with US 441 (Broadway). A short distance later, I-640 crosses a Norfolk Southern Railway mainline.[6] Some distance later, the freeway turns almost directly east. It then reaches an interchange with Washington Pike and Millertown Pike; access between the two is provided via frontage roads on both sides of the Interstate.[1] The highway then gradually shifts south and, a few miles later, crosses another Norfolk Southern mainline and US 11W (Rutledge Pike) without intersecting this route.[6] I-640 then reaches its eastern terminus at a semi-directional T interchange with I-40 on the eastern outskirts of Knoxville. Here, US 25W and SR 9 continue onto a brief unsigned concurrency with I-40, heading eastward toward Asheville, North Carolina.[1][4]


Planning and construction

1955 federal Bureau of Public Roads highway plan for Knoxville

The highway that is now I-640 had its origins in a plan commissioned by the city of Knoxville in 1945, which recommended that a series of expressways be constructed throughout the city to relieve traffic on surface streets.[7] It was initially known as the Dutch Valley Loop during its planning phase and roughly followed its current alignment.[8][9] Planners intended these freeways to be integrated into the then-proposed nationwide highway network that later became the Interstate Highway System, which, at the time, was expected to eventually be authorized by Congress.[7][10] After the passage of the Federal Aid Highway Act of 1956, which initiated the Interstate system, the highway was designated as I-640 by the American Association of State Highway Officials (AASHO) on November 12, 1958.[11]

Construction on the interchange between I-640, I-75, I-275, and US 25W began in February 1961,[12][13] as part of the project to build the segment of I-75 (now I-275) directly south of this interchange, which had begun construction in March 1958.[14] It was completed in November 1962 and dedicated on January 3, 1963.[15][16][17] On December 4, 1964, what is now the interchange between I-40/I-75 and a short segment of I-640 extending north to SR 169 (Middlebrook Pike) was opened to traffic, providing access between both routes to local motorists.[18] The connecting segment of I-40/I-75 was also opened to all traffic at the same time.[19] Work on the 2.2-mile (3.5 km) segment between I-75/I-275/US 25W and US 441 began in October 1968 and was completed on December 15, 1970.[20][21]

The remainder of I-640 was initially delayed by disputes over its final alignment and disagreements between the city of Knoxville and the state over the improvement of nearby surface streets.[22] In addition, new requirements imposed by the National Environmental Policy Act (NEPA) of 1969 required that an environmental impact statement (EIS) be prepared for the remaining segments.[23] Environmental studies took place between 1973 and 1978, with the Federal Highway Administration (FHWA) approving the EIS for the western leg in November 1975 and the EIS for the eastern leg in March 1978.[24][25] Construction of these sections was then funded as part of a $250 million (equivalent to $645 million in 2022[26]) multiphase improvement project on multiple roads in the Knoxville vicinity that was conducted in preparation for the 1982 World's Fair.[27][28]

Construction on the section between I-40/I-75 and I-75/I-275/US 25W began in October 1977,[29] and work to modify the Sharp's Gap Interchange, which included construction of two new flyover ramps, began in August 1978.[30][31] This section opened to traffic on December 23, 1980.[32][33] At this time, I-75 was rerouted onto this section, and the part of I-75 between I-640 and I-40 in downtown Knoxville was renumbered I-275.[34] This was done in an effort to divert through traffic on I-75 away from the World's Fair.[27] Work on the final section, located between US 441 and the eastern terminus with I-40, began in July 1979 and was opened to traffic on December 21, 1981.[35][36] Final signage, lighting, and landscaping work was completed in April 1982,[27] and the flyover ramp from I-40 eastbound onto I-640 at the eastern terminus opened on July 1, 1983.[37] Then-Governor Lamar Alexander officially opened both sections by leading a walk along their entire lengths dressed in his red plaid shirt that he famously wore during both of his campaigns for governor.[33][36] I-640 was the last Interstate Highway to be completed from the original 1956 allocation for the East Tennessee Grand Division.[33]

Later history

A new exit ramp from I-640 eastbound to Gap Road was constructed just east of the Sharp's Gap Interchange between December 18, 1985, and August 6, 1986, providing direct access to US 25W from the eastbound lanes for the first time.[38][39] The section of I-640 between the Sharp's Gap Interchange and US 441 was the only section of the route that was originally four lanes.[40] It was widened to six lanes between January 2000 and June 2003.[41][42] During this project, the interchange with US 441 was also reconstructed, eliminating a loop exit ramp from I-640 eastbound and reconfiguring parts of the other ramps.[41]

Between May 1, 2008, and June 12, 2009, through traffic passing on I-40 through Knoxville was required to use I-640 to bypass a complete closure of I-40 through downtown.[43] This was conducted as part of a larger project called "SmartFix 40" to reconstruct and improve this section of I-40. During this time, the ramps at both termini of I-640 carrying this traffic were temporarily widened to three lanes to facilitate the extra volume.[44]

Between April 2016 and July 2019, the interchange with US 441 was further modified. The exit ramp from I-640 westbound was lengthened, and a new loop entrance ramp from US 441 northbound onto I-640 westbound was constructed.[45] On October 21, 2019, the speed limit on I-640 was increased from 55 mph (89 km/h) to 65 mph (105 km/h), along with the speed limits on sections of other Knoxville-area Interstates, after the Tennessee Department of Transportation (TDOT) determined that the air quality had greatly improved in the area over the previous 15 years and that the vast majority of drivers were exceeding these limits by large margins.[46]

TDOT is currently reconstructing the mainline surface of I-640 in a two-phase project. The first phase, which took place in 2021, resurfaced the stretch between the Interstate's western terminus and the Sharp's Gap Interchange by removing one layer of asphalt and replacing it with two main layers and a binding layer.[47] The second phase, which began on July 10, 2022, and is expected to be completed in November 2023, involves reconstructing the stretch between the Sharp's Gap interchange and the eastern terminus by removing the asphalt surface and rubblizing the original underlying concrete surface to provide a base for a new asphalt surface.[48] The deterioration of the underlying concrete had made this stretch of roadway susceptible to forming cracks and potholes, and had been patched and repaired multiple times.[47]

Exit list

The entire route is in Knoxville, Knox County.


I-40 west / I-75 south – Nashville, Chattanooga
Western terminus; western end of I-75 concurrency; I-40 exit 385

I-40 east – Knoxville
Westbound left exit and eastbound entrance; I-40 exit 385
1.342.161 SR 62 (Western Avenue)Separate ramps provide access to SR 62 eastbound and westbound from eastbound lanes via collector–distributor lane; not signed as exits 1A and 1B

To US 25W north (SR 9 north) / Gap Road – Clinton
Eastbound exit only

US 25W north (SR 9 north) – Clinton
No eastbound exit; western end of US 25W/SR 9 concurrency

I-75 north / I-275 south – Knoxville, Lexington
Eastern end of I-75 concurrency; I-275 exit 3 and I-75 exit 107
6.049.726 US 441 (Broadway / SR 33 / SR 71) / Old Broadway (SR 331)Old Broadway signed eastbound only
8Washington Pike / Mall Road / Millertown PikePartially signed as Mall Rd. South eastbound, Mall Rd. North westbound
I-40 west – Nashville
Eastbound exit and westbound entrance; I-40 exit 393

I-40 east (US 25W / SR 9 south) – Asheville
Eastern terminus; eastern end of US 25W/SR 9 concurrency; I-40 exit 393
1.000 mi = 1.609 km; 1.000 km = 0.621 mi

See also


  1. ^ a b c d e f g Google (November 21, 2021). "Overview of Interstate 640" (Map). Google Maps. Google. Retrieved November 21, 2021.
  2. ^ "Interstate 640 Reconstruction". Nashville: Tennessee Department of Transportation. 2021. Retrieved November 20, 2021.
  3. ^ a b Tennessee Department of Transportation. "Transportation Data Management System". MS2. Retrieved November 27, 2021.
  4. ^ a b c d Tennessee Department of Transportation Long Range Planning Division Office of Data Visualization (2018). Knox County (PDF) (Map). Tennessee Department of Transportation.
  5. ^ "CSX System Map". CSX Transportation. Retrieved November 28, 2021.
  6. ^ a b "Norfolk Southern Railway System Map" (PDF). Norfolk Southern Railway. 2016. Retrieved November 29, 2021.
  7. ^ a b Smith, Walter (November 1945). Major Street System (Report). City of Knoxville, Tennessee. pp. 2–23.
  8. ^ "Knoxville Expressway System (Illustration)". The Knoxville Journal. January 24, 1957. p. 15. Retrieved November 28, 2021 – via
  9. ^ "Interstate Superhighway Program Bringing New Prosperity To East Tennessee". The Knoxville Journal. January 20, 1959. p. 10. Retrieved November 28, 2021 – via
  10. ^ Ferguson, Don K. (May 18, 2008). "Ferguson: First downtown expressway spurred Malfunction Junction". The Knoxville News-Sentinel. Retrieved June 6, 2020.
  11. ^ Report of the State Highway Commissioner of Tennessee for the Biennium ending June 30, 1960 (Report). Nashville: Tennessee Department of Highways. 1960. p. 57. Retrieved November 22, 2021 – via Google Books.
  12. ^ "Ground Broken for Gap Interchange". The Knoxville News-Sentinel. February 17, 1961. p. 9. Retrieved February 12, 2023 – via
  13. ^ "Interchange Job Starts (photo)". The Knoxville Journal. February 18, 1961. p. 5. Retrieved February 12, 2023 – via
  14. ^ Topp, Ed (March 25, 1958). "Expressway Link Work Order Given; North Route Job Approved by U.S." The Knoxville News-Sentinel. p. 1. Retrieved February 12, 2023 – via
  15. ^ "N. Central St. Extension OK'd". The Knoxville News-Sentinel. November 22, 1962. p. D-10. Retrieved February 12, 2023 – via
  16. ^ "Gap Interchange Dedication Is Tomorrow". The Knoxville News-Sentinel. January 2, 1963. p. 12. Retrieved February 12, 2023 – via
  17. ^ "Retiring Roads Chief To Stay In Department". The Knoxville Journal. January 4, 1963. p. 3. Retrieved February 12, 2023 – via
  18. ^ "Open All the Way Today; Twelve Interchanges (Illustrations)". The Knoxville Journal. December 4, 1964. p. 12. Retrieved November 21, 2021 – via
  19. ^ "Interstate 40 Section Opens". The Knoxville Journal. December 5, 1964. p. 9. Retrieved August 2, 2020 – via
  20. ^ "Road Work Begins At Broadway; State Drops Suit". The Knoxville Journal. October 24, 1968. p. 12.
  21. ^ "Dec. 15 Set As Finish for I-75 Connector". The Knoxville News-Sentinel. December 5, 1970. p. 3. Retrieved November 22, 2021 – via
  22. ^ "I-640 Impact Data Pushed; State Planning Mid-July Deadline". The Knoxville News-Sentinel. July 2, 1975. p. 1. Retrieved November 23, 2021.
  23. ^ Rogers, Al (August 26, 1977). "Highway Needs Surpass Funds, ET Officials Told". The Knoxville News-Sentinel. p. 15. Retrieved November 23, 2021.
  24. ^ Final Environmental Impact Statement, Administrative Action for Interstate 640 from the Existing Interchange with Interstate 40 Near Middlebrook Pike to a Point West of Gap Road in Knoxville, Knox County, Tennessee: Environmental Impact Statement. Tennessee Department of Transportation, Federal Highway Administration. 1975 – via Google Books.
  25. ^ Interstate 640 from State Route 33 (Broadway) to Interstate 40 East of Knoxville, in Knoxville, Knox County, Tennessee: Environmental Impact Statement. Tennessee Department of Transportation, Federal Highway Administration. 1978.
  26. ^ Johnston, Louis; Williamson, Samuel H. (2023). "What Was the U.S. GDP Then?". MeasuringWorth. Retrieved December 19, 2023. United States Gross Domestic Product deflator figures follow the Measuring Worth series.
  27. ^ a b c Knoxville-Knox County Metropolitan Planning Commission; Barton-Aschman Associates; Knoxville International Energy Exposition; K-Trans (December 1982). 1982 World's Fair Transportation System Evaluation (Report). Office of Planning Assistance, Urban Mass Transportation Administration. DOT-I-83-4. Retrieved June 6, 2020 – via Google Books.
  28. ^ Hunt, Keel (2018). Crossing the Aisle: How Bipartisanship Brought Tennessee to the Twenty-First Century and Could Save America. Nashville: Vanderbilt University Press. pp. 101–102, 117–129, 122. ISBN 978-0-8265-2241-2 – via Google Books.
  29. ^ "I-640 East Leg Progressing". The Knoxville Journal. November 1, 1977. p. 2.
  30. ^ "I-640-I-75 Interchange Work To Be in June 16 Bid Letting". The Knoxville News-Sentinel. May 20, 1978. pp. 1, 8. Retrieved February 12, 2023 – via
  31. ^ "I-640 East Leg Ramps To Be Open". The Knoxville News-Sentinel. December 17, 1980. p. A-1. Retrieved February 12, 2023 – via
  32. ^ "Alexander Opens Stretch of Interstate Allowing Downtown Knoxville Bypass". The Tennessean. Nashville. Associated Press. December 24, 1980. p. 3. Retrieved September 21, 2020 – via
  33. ^ a b c Brewer, Carson (December 23, 1980). "Governor Lifts Curse on Junction; Opens I-640". The Knoxville News-Sentinel. p. A3. Retrieved November 19, 2021 – via
  34. ^ "Governor To Open West Leg of I-640/75". The Knoxville News-Sentinel. December 21, 1980. p. B-10. Retrieved November 19, 2021 – via
  35. ^ "$32 Million Pacts OK'd for I-640 Work". The Knoxville News-Sentinel. July 14, 1979. p. 1. Retrieved November 21, 2021 – via
  36. ^ a b "Cool Governor Really Legs It as He, Others Open I-640 Leg". The Knoxville News-Sentinel. December 21, 1981. p. A-4. Retrieved November 19, 2021 – via
  37. ^ "Ramp Opens (photo)". The Knoxville News-Sentinel. July 3, 1983. p. B8. Retrieved December 30, 2021.
  38. ^ "I-640 exit ramp groundbreaking held". The Knoxville News-Sentinel. December 19, 1985. p. A13. Retrieved November 21, 2021 – via
  39. ^ Harris, Roger (August 6, 1986). "Can't-get-there-from-here woes being cured by Gap Road exit". The Knoxville News-Sentinel. p. A9. Retrieved November 21, 2021 – via
  40. ^ Moulton, John (March 16, 1978). "State Drops Proposal To Extend Seventeenth St". The Knoxville News-Sentinel. p. 21. Retrieved November 23, 2021 – via
  41. ^ a b "I-640 Widening". Qk4, Inc. Retrieved November 21, 2021.
  42. ^ "I-640/Broadway Project Wrapping Up". WBIR-TV. Knoxville. June 25, 2003.
  43. ^ "Interstate 40 Reopens In Knoxville 18 days ahead of schedule". Tennessee State Government Newsroom (Press release). Nashville. Tennessee Department of Transportation. June 12, 2009. Archived from the original on June 15, 2009. Retrieved June 15, 2009.
  44. ^ Jacobs, Don (April 13, 2008). "Downtown's 14-month I-40 shutdown will mean new routes, potential surprises". The Knoxville News-Sentinel. Retrieved January 31, 2021.
  45. ^ Della Volpe, Nick (August 16, 2019). "The Miracle on Broadway: I-640 interchange reduces hazards". Knox TN Today. Retrieved November 21, 2021.
  46. ^ Hoar, Lauren (October 21, 2019). "Speed limits increase on I-40, I-75, I-640 in Knoxville overnight". WBIR-TV. Knoxville. Retrieved November 20, 2021.
  47. ^ a b "Interstate 640 Reconstruction - Frequently Asked Questions". Tennessee Department of Transportation. Retrieved September 4, 2022.
  48. ^ Gallant, Kristen (July 1, 2022). "TDOT to begin $21 million I-640 reconstruction project in Knoxville". WATE-TV. Knoxville. Retrieved September 4, 2022.
  49. ^ Bureau of Transportation Statistics (June 13, 2022). "National Highway Planning Network" (Map). National Transportation Atlas Database. Washington, D.C.: United States Department of Transportation. Retrieved April 29, 2023.

External links