Interstate 24
Interstate 24 is an Interstate Highway in the Midwestern and Southeastern United States. It runs diagonally from I-57, south of Marion, Illinois, to Chattanooga, Tennessee, at I-75. As an even-numbered Interstate, it is signed as an east–west route, though the route follows a more southeast–northwest routing, passing through Nashville, Tennessee. Because the routing of I-24 is diagonal, the numbering deviates from the standard Interstate Highway System numbering conventions. I-24 constitutes the majority of a high-traffic corridor between St. Louis and Atlanta. This corridor utilizes I-64 and I-57 northwest of I-24, and I-75 southeast of I-24.
Route description
Illinois
I-24 begins at exit 44 on I-57 in southern Williamson County, near the community of Pulleys Mill. The highway heads southeast into rural Johnson County, bypassing Goreville to the east. It reaches an exit at Tunnel Hill Road, which serves Goreville and Tunnel Hill. The highway continues south to its next exit at U.S. Route 45 north of Vienna. It reaches its next exit at Illinois Route 146 in eastern Vienna. I-24 heads southeast from Vienna into Massac County. Its first exit in Massac County is at Big Bay Road, which serves the communities of Big Bay and New Columbia. I-24 continues southward, bypassing the community of Round Knob before entering Metropolis. The highway meets US 45 again in Metropolis and passes west of Fort Massac State Park. It leaves Metropolis and crosses the Interstate 24 Bridge over the Ohio River. After that, it continues into Kentucky.Kentucky
I-24 crosses into Kentucky on a bridge over the Ohio River. It passes to the west of Paducah and intersects US Routes 60, 45, and 62. The freeway then passes near Woodlawn-Oakdale and Reidland and connects with US 68. The welcome center in Paducah is a historic house, Whitehaven. This is the only historic house in the country used as a rest area. East of this point, I-24 runs concurrently with I-69. Through this, it intersects US 62 and crosses the Tennessee and the Cumberland Rivers. The roadway travels along the north shore of the Cumberland River. I-69 splits off to the east just north of Mineral Mound State Park. I-24 continues east, away from the river. It runs through farmland for several miles. It passes south of Hopkinsville and interchanges with I-169. Near the Tennessee border, I-24 passes north of Fort Campbell. Afterwards, it crosses into Tennessee.I-69 runs concurrently with I-24 for from Calvert City to Eddyville.
Tennessee
More of Interstate 24 is in Tennessee than in all other states combined.Clarksville to Nashville
I-24 crosses into Tennessee traveling in a southeasterly and northwesterly direction in Clarksville, Montgomery County. The first interchange is with SR 48. I-24 then has interchanges with US 79, SR 237, and SR 76, and crosses the Red River. It then enters a long straight section with several steep grades, crossing into Robertson County, and has interchanges with SR 256, and SR 49 near Springfield, respectively. The route then enters the rolling hilly terrain of the Nashville Basin, and crosses briefly into Cheatham County, where it has an interchange with SR 249. I-24 then crosses into Davidson County, and has an interchange with US 431. The interstate continues for several miles through rural woodlands and multiple steep grades before coming to an interchange with SR 45. Three miles later, I-24 crosses the Nashville Urban Boundary, widens to six lanes, and has an interchange with SR 155, the northern beltway around Nashville. Less than a mile later, I-24 joins a concurrency with Interstate 65, where the combined routes carry ten through lanes, and travel due south. About a mile later is an interchange with US 41A/431, and about a mile beyond this point, I-65 splits off, and I-24 enters downtown Nashville, where it has interchanges with US 41, US 431, and US 31E, as well as several city streets. I-24 then crosses the Cumberland River on the Silliman Evans Bridge, and joins in a concurrency with Interstate 40, travelling southeast with eight through lanes, and two miles later, I-40 splits off eastwardly, heading toward Knoxville. Located at this interchange is also an interchange with US 41/70S, and less than a mile later is an interchange with the eastern terminus of Interstate 440, which is also accessible from I-40 nearby. About a mile later is once again an interchange with SR 155/Briley Parkway near the Nashville International Airport, and I-24 continues southeast, bisecting a major residential area. Here I-24 carries eight through lanes, and beginning at the next exit, SR 255, the left lanes operate as HOV lanes during rush hour. Over the next few miles, I-24 has interchanges with Haywood Lane, SR 254, Hickory Hollow Parkway, and SR 253.Middle Tennessee
I-24 continues southeast through the suburbs of Nashville and crosses into Rutherford County near the city of LaVergne, where it has an interchange with a connector road to that city. Beginning at this point, I-24 is relatively straight and flat for most of its distance through Middle Tennessee. The straightest stretch of highway in Tennessee is located on I-24 between Lavergne and eastern Murfreesboro, where the route is perfectly straight for about fifteen miles, although the median widens and narrows. Two miles later, I-24 reaches Smyrna and has an interchange with SR 266. Four miles later is an interchange with SR 102, which also serves Smyrna, as well as the Nissan Smyrna assembly plant. Four miles later is an interchange with Interstate 840, the outer southern beltway around Nashville, and beyond this point I-24 enters Murfreesboro, the largest suburb of Nashville. In Murfreesboro, I-24 has interchanges with SR 96, SR 99, and US 231, respectively, and at the final Murfreesboro exit, the HOV lane designation ends, and I-24 narrows to six lanes and then four lanes a short distance later. Three miles later is an interchange with the Joe B. Jackson Parkway, which serves as an outer beltway around southeast Murfreesboro. I-24 then enters a more rural area, and remains relatively straight for many miles. Around milepost 96, I-24 briefly enters Bedford County, and then Coffee County, and at exit 97 has an interchange with SR 64, which connects to Shelbyville. I-24 then curves to the south, then the east, and several miles later at exit 105 is an interchange with US 41, and five miles later I-24 enters Manchester, where it has interchanges with SR 53, SR 55, and US 41, respectively. I-24 continues through a rural, largely agricultural area where it crosses into Grundy County and has an interchange with US 64 and SR 50.Monteagle Mountain
One of the most hazardous stretches of interstate highway in the United States is located approximately west of Chattanooga on I-24 in Monteagle, where the highway crosses the Cumberland Plateau. While all motorists need to exercise caution, truckers are particularly vexed by Monteagle, and many have died going through this area. The eastbound grade is particularly hazardous, with a protracted 4–6% grade over several miles. Compared to grades elsewhere in the state, this downgrade does not come close to the steepest. On this stretch, I-24 is three lanes in each direction, and contains two runaway truck ramps. Owing to geography, these two ramps are on the left side of the grade. The westbound downgrade of the plateau is also extremely hazardous, and contains several sharp curves. Portions of this downgrade also feature off-ramp approach style lane dividers, in order to slow both motorists and truckers. Throughout the entire stretch across the Cumberland Plateau, the speed limit reduces to a maximum of ; the westbound downgrade contains a speed limit for trucks, and the eastbound downgrade contains a maximum speed limit and limit for trucks.The eastern Monteagle grade also has one of the three widest medians 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 a mile 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 part of the original interstate path in this area.
Georgia and Chattanooga
After crossing Monteagle Mountain, I-24 travels for several miles through a relatively flat and straight segment before reaching an interchange with US 72 near Kimball and South Pittsburg. About later, I-24 has an interchange with SR 28 in Jasper. Beyond this point, the east and westbound lanes split more than apart, encompassing farms, homes, and a few businesses in between. This was reportedly a result of extensively fought disputes over right-of-way acquisitions, and is also one of the widest medians of any highway. The route then crosses a mountain, has an interchange with SR 27, and about later, crosses the Nickajack Lake impoundment of the Tennessee River. Beyond this point, traveling through a gorge, I-24 can experience potentially strong crosswinds for several miles. I-24 enters Hamilton County entering the Eastern Time Zone, and then into Georgia less than later.In the state of Georgia, I-24 travels for, traveling along the southern flank of Raccoon Mountain and having an interchange with I-59 before turning back north to the Tennessee River and around the northern flank of Lookout Mountain. The exits remain numbered according to Tennessee's mileposts; however, the roadway mileposts are numbered according to Georgia's mileposts. This segment also carries the unsigned State Route 409 designation.
Upon re-entering Tennessee and Hamilton County, I-24 travels through Lookout Valley for several miles, and has interchanges with several key roads, including US 11/US 41/US 72. Several miles later, I-24 curves sharply to the east, traveling on a causeway between the Tennessee River and the northern tip of Lookout Mountain, and about later, curves sharply to the north. Entering Chattanooga, less than later is a three-way interchange with US 27 northbound, which is a freeway beyond this point. Forming a concurrency with US 27, the highways then curve sharply to the east, then to the west about later, where US 27 splits off to the south as Rossville Boulevard. With interchanges with several city streets, I-24 travels through the inner city of Chattanooga. About later, I-24 reaches the "Ridge Cut", a section of Missionary Ridge, between the 4th Avenue exit and the Germantown/Belvoir exit, where the interstate curves sharply to the north, then to the east again, crossing the ridge with an extremely steep grade. Accidents and severe congestion are common here. About later, I-24 reaches its eastern terminus with I-75 in East Ridge.
The entire length of I-24 is part of the National Highway System, a system of routes determined to be the most important for the nation's economy, mobility, and defense.
History
Early history
The section of I-24 between Nashville and Chattanooga was part of the original Interstate Highway System plan enacted in 1956. Two of the first sections of I-24, both in Tennessee, began construction in 1958. These included the section between downtown Nashville and the Rutherford County line, and the eastern terminus with I-75.In Tennessee, I-24 was constructed in segments. In Chattanooga, the interstate was complete through the central part of town in 1962, and the rest of the city in 1965. The Ridgecut section, the final section, was dedicated on December 1 of that year. The segment between US 27 and the Georgia state line was completed in the fall of 1966. In Nashville, the segment between the split with I-40 and the split with I-65 was dedicated on January 14, 1964. I-24 was complete in Marion County to Monteagle Mountain in 1966 and between US 41 in Manchester and US 64 near Pelham on July 27, 1967. I-24 was constructed over Monteagle Mountain between 1962 and 1968. The route was opened between SR 171 in Nashville and US 231 in Murfreesboro on December 31, 1970. The last segment of I-24 between Nashville and Chattanooga, the segment located between SR 64 near Beechgrove and US 41 northwest of Manchester, was opened and dedicated on December 16, 1971. Work began on I-24 from the Kentucky line through Clarksville in 1970, and construction on the entirety of I-24 between Clarksville and Nashville was underway by 1972, with an estimated completion date of late 1974 or early 1975. Construction on this approximately segment, the last segment of mainline interstate highway completed in Tennessee, proved to be difficult due to the rugged and hilly terrain. The approximately segment between U.S. 68 in Hopkinsville, Kentucky and U.S. 79 in Clarksville, Tennessee was jointly opened to traffic by both states on September 12, 1975. The section between U.S. 79 and SR 49 in Robertson County was completed in September 1976. The last segment of I-24 in Tennessee, between SR 49 and Interstate 65 in Nashville, was opened to traffic on January 7, 1978, more than two years behind schedule.
In Kentucky, I-24 broke ground in December 1967 in Lyon County. The Ohio River Bridge opened in October 1974 at a cost of $18.6 million. The section of I-24 in Illinois was authorized for engineering by 1966 and authorized for construction by 1968. The final segment in Illinois opened to traffic in late January 1976 at a cost of $32.5 million. I-24 was completed when a 23-mile section opened to traffic from Western Kentucky Parkway to U.S. 68 east of Cadiz, Kentucky on May 23, 1980.
In 1979, structural problems were discovered on the Ohio River Bridge, including 119 cracks as a result of defective welding in the tie girders. The bridge was closed on August 3, 1979, and remained closed to all traffic through October 1980 and all truck traffic until the summer of 1981.
Recent history
Since its completion, Interstate 24 has seen many upgrades. The approximately segment between Haywood Lane in Nashville and SR 266 in Smyrna was widened from four to eight lanes between June 1997 and December 1998, installing the first HOV lanes on I-24. The portion between SR 266 and I-840 was widened from four to eight lanes between August 1998 and November 2000. The segment between I-440 and Haywood Lane was widened from three to four lanes in each direction between March 2000 and May 2002 in a project that also improved the interchanges on this segment. Widening of the segment between I-840 and SR 96 began in early 2004 and was completed in the summer of 2005. This project added a new interchange at Medical Center Parkway. A project that widened I-24 from four to eight lanes between SR 96 and US 231, and also added a new interchange with SR 99 began in April 2006 and was completed on January 28, 2008.On May 18, 2010, it was announced that a sinkhole was found near Exit 127 in the eastbound lanes of I-24 in Grundy County, Tennessee, near the exit to Tennessee State Route 50. Tennessee Department of Transportation officials stated that the hole was growing, with traffic diverted onto the westbound lanes. However, emergency repairs commenced and the highway was reopened several days later.