<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> 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>
where does time change on i 40 in tn
where does time change on i 40 in tn
mile 340
mile 340