was the only section of the route that was originally four lanes. It was widened to six lanes between January 2000 and June 2003. 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. Between May 1, 2008, and June 12, 2009, through traffic passing on I-40 through Knoxville was required to use I-640 due to a complete closure of I-40 through downtown. This was conducted as part of a larger project called "SmartFix 40", and, 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. 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. On October 21, 2019, the speed limit on I-640 was increased from to , 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. 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. 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. 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. Exit list See also References External links Interstate 640 at Interstate-Guide.com 40-6 40-6 640 Transportation in Knox County, Tennessee Transportation in Knoxville, Tennessee 640