<P> About ten miles later, I - 40 has an interchange with the western terminus of State Route 155 (Briley Parkway), the northern controlled - access beltway around Nashville . About two miles later is the western terminus of I - 440, the southern loop around central Nashville . Two miles later, I - 40 enters Downtown Nashville, and has interchanges with several major highways and surface roads . In Nashville, I - 40 shares brief concurrences first with I - 65 and then I - 24, before splitting off . The eastern terminus of I - 440 is directly accessible from the easternmost interchange with I - 24 . About 1.5 miles later, I - 40 has an interchange with SR 155 (Briley Parkway) near the Nashville International Airport . The route continues east for the next 20 miles through a still - developing area with eight lanes, the left lanes functioning as HOV lanes during rush hour, passing near the suburbs of Mount Juliet and Gallatin . At mile 219, I - 40 crosses the Stones River just downstream from the Percy Priest Dam . About 25 miles east of Nashville, the route narrows back to four lanes and has an interchange with the eastern terminus of I - 840 a few miles east of Lebanon . The interstate continues for roughly 50 miles (80 km) across mostly open farmland, passing near mostly small communities . </P> <P> In Smith County between mileposts 263 and 266, I - 40 crosses the meandering Caney Fork River five times before ascending the Eastern Highland Rim, reaching 1,000 feet (300 m) for the first time in the state near Silver Point . The interstate remains relatively flat across the plateau, beginning at the edge of the table - top rim at mile marker 272 near Baxter . The highway continues for about 15 miles through a mix of farmland and woodlands, before reaching Cookeville, where it has interchanges with several highways including SR 111, a major north - south connector to Chattanooga . For the next 20 miles, I - 40 passes through a predominantly wooded area, ascending the western escarpment of the Cumberland Plateau and reaching elevations above 2,000 feet (610 m), before reaching Crossville . At mile 308, I - 40 crosses the Tennessee Divide, where the Cumberland and Tennessee River watersheds meet . The divide is marked in the eastbound lanes with a sign reading "Entering Emory River watershed ." In the westbound counterparts is a sign noting the beginning of the Caney Fork watershed . </P> <P> I - 40 remains relatively flat and straight as it continues across the Cumberland Plateau and passes through the northern part of Crossville . East of Crossville, the Crab Orchard Mountains, the southern fringe of the Cumberland Mountains, come into view as the road descends several hundred feet . At mile 329, the interstate enters Crab Orchard Gap and proceeds through a narrow valley once prone to rockslides . At mile 340, the Interstate crosses into Roane County entering the Eastern Time Zone, and shortly thereafter the road begins its descent of the Cumberland Plateau into the Tennessee Valley and the speed limit is 60 mph to 70 mph . I - 40 hugs the slopes of the plateau's Walden Ridge escarpment for several miles, containing what some describe as dramatic views of the Tennessee Valley below to the south, before reaching the base of the plateau at mile 347 between Harriman and Rockwood . As it enters the Ridge - and - Valley province of the Appalachians, of which the Tennessee Valley is a part, I - 40 crosses a series of ridges and valleys characteristic of the region's topography . At mile 351, the road crosses the Clinch River, with the Kingston Fossil Plant and its 1,000 - foot (300 m) twin smokestacks dominating the view to the north . </P> <P> At exit 368, about 20 miles west southwest of downtown Knoxville, I - 40 merges with I - 75, which continues to the southwest to Chattanooga, and widens to six lanes . The two highways pass through several of the suburbs of Knoxville, and exits are numbered according to I - 40 mileage along this stretch . At exit 374 (SR 131 / Lovell Road), the highway widens to eight lanes and the speed limit drops to 55 mph., and at the next exit, has an interchange with the Pellissippi Parkway (SR 162 westbound, Interstate 140 eastbound), which connects to Oak Ridge and Maryville, respectively . At exit 385 is an interchange with the western terminus of Interstate 640, a beltway which passes northwest of downtown Knoxville . Also at this exit, I - 75 splits off from I - 40 onto a concurrency with I - 640, splitting off a few miles later and heading towards Lexington, Kentucky . The route then enters downtown Knoxville, passing near the main campus of the University of Tennessee, as well as several residential neighborhoods, and has interchanges with US 129, I - 275, US 441, and SR 158 . I - 40 is a minimum of six through lanes through the entirety of central Knoxville, containing several short segments of auxiliary lanes between exits . The highway then enters a predominantly residential area, passing next to the Knoxville Zoo, before coming to an interchange with the eastern terminus of I - 640 and leaving Knoxville . </P>

Where does time change on i 40 in tn