The section of I-24 known,
tautologically, as Monteagle Mountain consists of a segment in
Grundy and
Marion counties that includes both the eastern and western
escarpment of the
Cumberland Plateau. I-24 also
travels concurrently with
U.S. Route 64 (US 64) through this section. I-24 crosses the plateau in its narrowest section, which appears as an
hourglass shape on maps. Monteagle Mountain is best known for its eastern descent, but its western descent is also one of the most hazardous stretches of
Interstate Highway as well. Compared to grades elsewhere, Monteagle's 4–6% grade over a period of several miles does not come close to the steepest. The route contains six lanes over the eastern escarpment, with the extra lane on the westbound side serving as a
truck climbing lane, and four lanes over the western escarpment. The
Tennessee Department of Transportation (TDOT) has yet to construct a truck lane on the western ascent. On the eastern descent of the plateau, the eastbound lanes contain a 6% grade over a length of about where the elevation drops , and is particularly hazardous to truckers. At the top of this downgrade is a
truck inspection station, and this downgrade also contains two
runaway truck ramps, which are on the left due to the terrain. The speed limit on the eastbound lanes reduces to and for trucks, while on the westbound lanes it reduces to , with no separate restrictions for trucks. The eastern downgrade of Monteagle Mountain also contains the third-widest median of any Interstate Highway, with the others being
I-8 through the
In-Ko-Pah grade in
California and
I-84 through the Cabbage Hill grade east of
Pendleton, Oregon.. There is more than between the eastbound and westbound lanes at one point. The eastbound lanes descend the mountain on one side of a ridge, while the westbound lanes ascend the other, and are located on what was originally US 64. The westbound ascent is approximately longer than the eastbound descent, making the westbound side slightly out of line with mileage signing. The western downgrade of Monteagle Mountain on I-24 drops over , with a 5% grade. While not considered as hazardous as the eastbound descent, the westbound descent contains many curves, including one "c-shaped" curve, protracted over a distance of almost . The eastbound and westbound lanes are also located very close together, and crossover crashes and crashes with
Jersey barriers located in the median in some places are common on this stretch. This segment also features off-ramp approach-style lane dividers, in order to slow both motorists and truckers. The speed limit on the downhill westbound lanes, of this stretch is and for trucks, while on the uphill eastbound lanes it is , with no separate restrictions for trucks. The approximately on top of the mountain, which contains exits with
US 41 and
US 41A, is not hazardous, but maintains the speed limit. A
rest area is located at the top of the western escarpment of Monteagle Mountain. East of the grade, the route passes through a narrow valley alongside Battle Creek, with slight banked curves as it enters
Kimball and
South Pittsburg. West of the grade, the route enters the relatively flat terrain of the
Eastern Highland Rim, passing through
Pelham. == Background ==