Interstate 40 in Tennessee

The Hernando de Soto Bridge carries I-40 across the Mississippi River from Arkansas into Memphis

I-40 enters Tennessee in a direct east–west alignment via the six-lane Hernando de Soto Bridge, a tied-arch bridge which spans the Mississippi River and has a total length of approximately 1.8 miles (2.9 km). Immediately within the city of Memphis, Tennessee's second-largest city, the interstate crosses the southern half of Mud Island before crossing the Wolf River Harbor and Mississippi Alluvial Plain into downtown Memphis, where the bridge ends next to the Memphis Pyramid. The highway then has an interchange with U.S. Route 51 (US 51, Danny Thomas Boulevard), and about one mile (1.6 km) later, abruptly turns 90° north at an interchange with the western terminus of I-240, a southern bypass route around the central city, near Midtown. A short distance later is an interchange with State Route 14 (SR 14, Jackson Avenue). Proceeding northward, the freeway crosses the Wolf River and reaches the eastern terminus of SR 300, a controlled-access connector to US 51. Here, the interstate shifts due east, bypassing the central part of Memphis to the north. Passing near the neighborhoods of Frayser and Raleigh, I-40 intersects with multiple surface streets and crosses the Wolf River for a second time about five miles (8.0 km) later. It then meets SR 14 again, and turns southeast, reaching SR 204 (Covington Pike) a short distance beyond.[8][9]

About two miles (3.2 km) beyond this point, I-40 reaches a complex four-level stack interchange with US 64/US 70/US 79 (Summer Avenue) and the eastern termini of I-240 and Sam Cooper Boulevard, where a pair of flyover ramps transfer the interstate's path to the northeast. The highway then crosses the Wolf River for a third and final time about 1⁄2 mile (0.80 km) later. Entering a long straightaway, the interstate passes through the suburban neighborhoods of East Memphis and Cordova, as well as the incorporated suburb of Bartlett in eastern Shelby County, over the next several miles. This stretch carries eight lanes, with the left lanes serving as HOV lanes during rush hour, and provides several interchanges with local thoroughfares. After about 7 miles (11 km), the highway reaches an interchange with US 64, where it narrows to four lanes. After passing through Lakeland, the interstate reaches a cloverleaf interchange with the eastern termini of I-269 and SR 385 some distance later near the suburb of Arlington.[8][9]

I-40 eastbound in Jackson

Leaving the Memphis, I-40 enters rural Fayette County about one mile (1.6 km) east of Arlington, and about five miles (8.0 km) later crosses the Loosahatchie River and adjacent wetlands. Over the next 30 miles (48 km), the interstate crosses a flat and level expanse of farmland and some rural woodlands and swamplands in a straight alignment, bypassing most cities and communities. At exit 35 is an interchange with SR 59, which provides access to Covington and Somerville. About eight miles (13 km) later, the highway enters Haywood County near the site of Ford Motor Company's future Blue Oval City manufacturing facility, and about 10 miles (16 km) later, turns north and enters the Hatchie National Wildlife Refuge. Over the next four miles (6.4 km), the interstate crosses the Hatchie River and multiple streams and swamps in a long straightaway. Upon exiting the refuge, I-40 turns east and passes southeast of Brownsville, where it has interchanges with SR 76, SR 19, and US 70 over a distance of about 8 miles (13 km). The highway then enters Madison County.[9]

Traversing through a mix of additional level farmland and swamplands, I-40 enters Jackson several miles later, and crosses the South Fork of the Forked Deer River. Passing through the northern half of Jackson, the interstate temporarily widens to six lanes and has a total of six exits. First, at exit 79, is US 412, which also connects to Alamo and Dyersburg. Then, about one mile (1.6 km) later is an interchange with the US 45 Bypass. About 1+1⁄2 miles (2.4 km) later is an interchange with US 45 (North Highland Avenue), which also provides access to Humboldt and Milan. Advancing into a residential area, the interstate reaches an interchange with US 70, which also connects to Huntingdon, about five miles (8.0 km) later. I-40 leaves Jackson beyond this point.[10][9]

From here, the interstate continues east-northeast through a sparsely populated territory of farmland and woodlands characterized by low rolling hills, and about seven miles (11 km) later enters Henderson County and crosses the Middle Fork of the Forked Deer River a few miles beyond. Some distance later, near the town of Parkers Crossroads, I-40 has an interchange with SR 22, a major north–south corridor in West Tennessee, providing access to Lexington and Huntington. A few miles later, the interstate crosses the Big Sandy River before proceeding through the northern half of Natchez Trace State Park. Over the next several miles, the highway transitions multiple times between Henderson and Carroll Counties, before entering Decatur County around milepost 120. About six miles (9.7 km) beyond this point is an interchange with US 641/SR 69, another major north–south corridor, which at this point connects to Camden and Decaturville. The interstate then enters Benton County. About six miles (9.7 km) later, the interstate descends about 300 feet (91 m) on a steep grade over the course of one mile (1.6 km) into the Western Valley of the Tennessee River, with the westbound lanes utilizing a truck climbing lane. Entering Tennessee National Wildlife Refuge at the bottom of this grade, I-40 crosses the Kentucky Lake impoundment of the Tennessee River on the 1⁄2 mile (0.80 km) Jimmy Mann Evans Memorial Bridge into Middle Tennessee.[9]

Traversing the Western Highland Rim in Hickman County

Upon crossing the Tennessee River into Humphreys County, I-40 exits the refuge a short distance later, and traverses through vast woodlands in the rugged hills of the Western Highland Rim for a considerable distance. This section is characterized by several noticeable upgrades and downgrades, with the route roughly following a natural crooked stream valley. About six miles (9.7 km) beyond the river, the highway crosses the Buffalo River. A short distance later is an interchange with SR 13, which connects to Linden and Waverly. About five miles (8.0 km) later, the interstate descends another steep grade, once again utilizing a westbound truck climbing lane, and crosses into Hickman County. A short distance later it reaches SR 50, which connects to Centerville. The highway then crosses the Duck River, traveling through additional wooded areas characterized by further rugged terrain and gradually ascending. It then reaches SR 48, which provides access to Centerville and Dickson. I-40 then enters Dickson County, and shortly beyond this point crosses the Piney River.[9]

About six miles (9.7 km) beyond this point is an interchange with SR 46, the primary exit for Dickson, which also provides access to Centerville and Columbia. Four miles (6.4 km) later, I-40 has an interchange with the western terminus of I-840, the outer southern beltway around Nashville. The highway continues through woodlands and rugged terrain, and crossing into Williamson County, ascends steeply over a short distance, gaining an eastbound truck climbing lane. Along this ascent, about six miles (9.7 km) beyond I-840, is an interchange with SR 96, which connects to the Nashville suburbs of Fairview and Franklin. Approaching the urban parts of the Nashville metropolitan area, the interstate enters Cheatham County a few miles later, and gradually descends into the Nashville Basin. A short distance later, the highway passes the towns of Kingston Springs and Pegram, and crosses the Harpeth River twice over a distance of about 1.5 miles (2.4 km).[9]

I-40 near the Nashville International Airport looking west

Around milepost 191, I-40 enters Davidson County, and a few miles later crosses the Harpeth River for a third time. About one mile (1.6 km) later, near Bellevue, the interstate widens to six lanes. Entering the urban outskirts of the state capital of Nashville, the highway has an interchange with US 70S near a bend in the Cumberland River. The highway then has an exit with SR 251 (Old Hickory Boulevard), and two miles (3.2 km) later once again intersects with US 70 (Charlotte Avenue). I-40 then widens to eight lanes, and in three miles (4.8 km) has a four-level interchange with SR 155 (Briley Pkwy, White Bridge Road), which includes the western terminus of a northern controlled-access beltway around Nashville. About two miles (3.2 km) later, south of Tennessee State University, is the western terminus of I-440, the southern loop around central Nashville, where the interstate reduces to six lanes.[11][9]

I-40 passes through the Jefferson Street neighborhood over the next two miles (3.2 km), before entering downtown Nashville near Fisk University. Here, the highway begins a brief concurrency with I-65, turning southeast. As part of the freeway that encircles downtown Nashville known locally as the Downtown Loop or Inner Loop, the two concurrent interstates have interchanges with US 70 (Charlotte Avenue), US 70S/US 431 (Broadway), Church Street, and Demonbreun Street. After about two miles (3.2 km), the concurrent routes shift east-northeast near Music Row and the neighborhoods of The Gulch and SoBro, and I-65 splits off, heading south towards Huntsville, Alabama. Briefly independent for about one mile (1.6 km), I-40 crosses a long viaduct, and has an interchange with US 31A/US 41A (4th Avenue, 2nd Avenue), before beginning a brief concurrency with I-24. The concurrent routes then turn southeast, expanding back to eight lanes. About two miles (3.2 km) later, I-24 splits off to the southeast, signed for Chattanooga, and I-40 shifts eastward. The eastern terminus of I-440 and a connector road to US 41/70S (Murfreesboro Road) are also directly accessible from the westbound lanes of I-40 at this interchange.[11][9]

Entering the Donelson neighborhood, I-40 has an interchange with SR 155 (Briley Parkway) about 1+1⁄2 miles (2.4 km) later near the Nashville International Airport. Beginning here, the left lanes function as HOV lanes during rush hour. A short distance later, the eastbound lanes have a partial exit to an airport connector road; only the westbound lanes of I-40 are accessible from this interchange. Less than one-half mile (0.80 km) later is an exit to SR 255 (Donelson Pike), another important means of access to the airport. Shifting northeast, the interstate intersects with Stewarts Ferry Pike a few miles later, and then crosses the Stones River near J. Percy Priest Dam. Entering the southern fringes of the Hermitage neighborhood, the highway has an interchange with SR 45 (Old Hickory Boulevard) a short distance later and once again shifts eastward into a straightaway.[11] About three miles (4.8 km) later, I-40 enters Wilson County, and a short distance later has an interchange with SR 171 in the Nashville suburb of Mount Juliet. Entering another long straightaway, some distance later the interstate intersects with SR 109, which provides access to Gallatin to the north. About three miles (4.8 km) later, the highway has a trumpet interchange with the eastern terminus of I-840 a short distance east of Lebanon. It then enters Lebanon, reduces back to four lanes, and has interchanges with US 231 and US 70.[12][9]

For the next roughly 25 miles (40 km), I-40 continues across mostly open farmland, passing near multiple small communities. About 10 miles (16 km) east of Lebanon, it enters Smith County, and begins a steep ascent over about 2+1⁄2 miles (4.0 km) where the eastbound lanes gain a truck climbing lane. Nearly six miles (9.7 km) beyond this point is an interchange with SR 53 in Gordonsville and near Carthage. Between mileposts 263 and 266, the highway crosses the meandering Caney Fork River five times before crossing into Putnam County. Shortly thereafter, I-40 has an interchange once again with SR 96 in Buffalo Valley, where it shifts southeast and begins its ascent out of the Nashville Basin onto the Eastern Highland Rim. This grade is moderately steep, and is protracted over a distance of about four miles (6.4 km).[9] Near the top of this ascent, the interstate reaches an elevation of 1,000 feet (300 m) for the first time in Tennessee near Silver Point.[13] Upon reaching the top of the rim, the highway curves northeast and has an interchange with SR 56 southbound and the eastern terminus of SR 141, the former of which connects to Smithville and McMinnville.[9]

Beginning a concurrency with SR 56 at this point, I-40 gradually shifts eastward over the next seven miles (11 km), before reaching Baxter, where SR  splits off and heads north towards Gainesboro. Reaching Cookeville about five miles (8.0 km) later, the interstate has a total of five interchanges, including one with SR 111, a major north-south connector to Chattanooga, and another with US 70N. A few miles beyond this point, the interstate begins a steep ascent onto the Cumberland Plateau, protracted over a distance of about five miles (8.0 km), and reaches an elevation of nearly 2,000 feet (610 m) at the top. Along this section, the speed limit reduces to 65 mph (105 km/h), and 55 mph (89 km/h) for trucks on the westbound descent. The interstate then continues through a wooded area for a short distance before reaching Monterey a few miles later and turning southeast. Here, I-40 has two interchanges with US 70N, the first of which carries a concurrency with SR 84.[9] A short distance later, the highway reaches an elevation of 2,000 feet (610 m) for the first time in Tennessee, just before crossing into Cumberland County and East Tennessee.[13]

I-40 eastbound descending Walden Ridge, part of the Cumberland Plateau

After ascending further up onto the Cumberland Plateau, I-40 remains moderately flat and straight as it continues east through a mix of wooded areas and farmland. At mile marker 308, the highway crosses the Tennessee Divide, where the Cumberland and Tennessee River watersheds meet.[9] About 10 miles (16 km) later, the interstate reaches Crossville, where it crosses the Obed River. Here the interstate has three interchanges, including one with US 127, which also connects to Jamestown.[14] East of Crossville, the Crab Orchard Mountains, the southern fringe of the Cumberland Mountains, come into view as the road descends several hundred feet, with the westbound lanes utilizing a truck climbing lane over part of this elevation change.[9]

A short distance beyond this point, I-40 has an interchange with a connector road to US 70 near the town of Crab Orchard. Then, the interstate enters Crab Orchard Gap, proceeding through a narrow pass at the base of the Cumberland Mountains once prone to rockslides. This section is characterized by several relatively sharp curves. Beyond this point, the highway ascends upwards over a short distance, with the eastbound lanes utilizing a truck climbing lane. A short distance later, I-40 crosses into Roane County, also transitioning from Central to Eastern Time Zone at this point.[14] Shortly thereafter the interstate curves to the northeast, and begins its descent off of the Cumberland Plateau into the Ridge-and-Valley Appalachians, also known as the Tennessee Valley or Great Valley of East Tennessee. Along this descent, the speed limit drops to 60 mph (97 km/h) in the eastbound lanes.[14] The highway 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, before reaching the base of the plateau about 800 feet (240 m) below.[13] I-40 then shifts eastward between Harriman and Rockwood, and has an interchange with US 27.[9]

Beyond this point, I-40 crosses a series of paralleling ridges and valleys characteristic of the region's topography. About four miles (6.4 km) later is an interchange with SR 29, and about one mile (1.6 km) later, the highway crosses the Clinch River on the Sam Rayburn Memorial Bridge, with the Kingston Fossil Plant and its 1,000-foot (300 m) twin smokestacks dominating the view to the north. About one mile (1.6 km) later is an interchange with SR 58 southbound in Kingston, where the interstate begins a brief concurrency with this route. After ascending a short and relatively steep ridge out of the Clinch River Valley, SR 58 splits off to the north about four miles (6.4 km) later, heading towards Oak Ridge. Continuing through the rugged terrain of the Great Appalachian Valley and traversing additional ridges, the interstate enters Loudon County about seven miles (11 km) later and has an interchange with US 321/SR 95 near Lenoir City, before reaching I-75 about four miles (6.4 km) later.[9]

I-40 concurrent with I-75 in Knoxville, with a variable-message sign visible

At exit 368, about 20 miles (32 km) west-southwest of downtown Knoxville, I-40 merges with I-75, which continues to the southwest to Chattanooga. The two routes turn east-northeast, carrying six through lanes, and cross into Knox County a short distance later. Throughout this concurrency, exits are numbered according to I-40's mileage. After gradually ascending a steep ridge, the two interstates shift onto a long straight alignment and pass through Farragut, a western suburb of Knoxville. Here they have an interchange with a local thoroughfare. Upon reaching SR 131 (Lovell Road), the road widens to eight lanes and a short distance later has an interchange with the Pellissippi Parkway (SR 162 westbound, I-140 eastbound), which connects to Oak Ridge and Maryville, respectively.[15][9]

Proceeding through West Knoxville, the two routes have interchanges with additional local roads, before reaching a connector to US 11/US 70 (Kingston Pike) four miles (6.4 km) later near the West Hills neighborhood. A short distance later is an interchange with SR 332 (Northshore Drive), and the separate Papermill Drive and Weisgarber Road.[15] This segment of I-40 and I-75 is the most heavily traveled section of highway in Tennessee, with an annual average daily traffic volume of more than 210,000 vehicles.[16] Two miles (3.2 km) later, the routes reach the western terminus of I-640, a beltway which bypasses Downtown Knoxville to the north. Here, I-75 splits off from I-40 onto a brief concurrency with I-640, splitting off a few miles later and heading towards Lexington, Kentucky. The interstate then enters downtown, containing a minimum of six through lanes, as well as several short segments of auxiliary lanes between exits.[15][9]

Passing near the main campus of the University of Tennessee, as well as several residential neighborhoods, the Interstate first reaches an interchange with the northern terminus of US 129 (Alcoa Highway), a controlled-access highway that provides access to McGhee Tyson Airport and the Great Smoky Mountains National Park. Just under one mile (1.6 km) later is an exit with SR 62 (Western Avenue), and one mile (1.6 km) beyond this point is a three-level interchange with the southern terminus of I-275. Here, the eastbound lanes also have access to US 441 southbound (Henley Street). The highway then crosses a long viaduct over a railyard, before reaching a directional T interchange with SR 158 (James White Parkway) westbound, a controlled-access highway that provides direct access to Downtown Knoxville to the south.

I-40 then curves due north, and about 1⁄2 mile (0.80 km) later, northeast again before coming to an interchange with a connector to US 441. It enters a predominantly residential area, passing by Zoo Knoxville, and reaches an interchange with US 11W (Rutledge Pike) a few miles later. Less than one mile (1.6 km) beyond this point, the Interstate reaches the eastern terminus of I-640, shifting eastward. Also at this interchange, it begins a brief unsigned concurrency with US 25W and SR 9, which split slightly over one mile (1.6 km) later at an interchange with US 11E/US 70 (Asheville Highway). Leaving Knoxville, the Interstate crosses the Holston River about two miles (3.2 km) beyond.[15][9]

I-40 near mile 441, with Mount Cammerer rising in the distance

Continuing east as a six-lane highway, I-40 travels through the semi-rural Strawberry Plains community before crossing into Sevier County several miles later.[15] About two miles (3.2 km) beyond this point, near Sevierville, I-40 has an interchange with SR 66 and the northern terminus of the Great Smoky Mountains Parkway, beginning an unsigned concurrency with the former. This interchange is the primary means of access to the Great Smoky Mountains National Park, as well as the tourist attractions in the cities of Sevierville, Pigeon Forge, and Gatlinburg, and as a result, is one of the busiest and most congested non-interstate exits in the state. Gradually turning northeastwardly, the highway crosses into Jefferson County a few miles beyond this point, and after a gradual ascent over a distance of about five miles (8.0 km), has an interchange with US 25W/US 70 near Dandridge. SR 66 also splits off at this interchange, but there is no signage for this. Two miles (3.2 km) later is an interchange with SR 92 in Dandridge. I-40 then reaches an interchange about four miles (6.4 km) later with the southern terminus of I-81, which runs into northeast Tennessee to the so-called "Tri-Cities" of Bristol, Kingsport, and Johnson City. Here, the interstate reduces back to four lanes and turns 90° southeast.[17][18]

Beginning a moderate descent, I-40 crosses the Douglas Lake impoundment of the French Broad River a few miles later, and enters Cocke County about five miles (8.0 km) beyond after a small elevation gain.[18] A short distance later is an interchange with US 411/US 70/US 25W near Newport. Traveling along the northern base of English Mountain for a few miles, the interstate turns southward and has an interchange with US 321 three miles (4.8 km) later. About five miles (8.0 km) beyond the road has an interchange with SR 73 near Cosby, and veers almost directly south, revealing a dramatic view of the 4,928-foot (1,502 m) Mount Cammerer at the northeastern end of the Great Smoky Mountains. A few miles later the highway crosses the Pigeon River and has an interchange with the eastern terminus of the Foothills Parkway, before crossing the Pigeon River again about 1+1⁄2 miles (2.4 km) later and curving sharply to the east. At this point, I-40 enters the Cherokee National Forest and proceeds into the Pigeon River Gorge between the Great Smoky Mountains to the south and the Bald Mountains to the north, closely following the north bank of the river. This section is extremely curvy and susceptible to accidents, and as a result, the speed limit reduces to 55 mph (89 km/h) and trucks are prohibited from using the left lane. This stretch is also prone to rockslides, and contains mesh nets along some of the cliff slopes as preventive measures. About two miles (3.2 km) later, the route curves to the south again near the unincorporated community of Hartford. About four miles (6.4 km) later, the highway crosses the Appalachian Trail and enters North Carolina a short distance beyond.[19][9]

Music highway sign at an I-40 rest area in Benton County honoring country singers Loretta Lynn and Hank Williams

The name Music Highway refers to the section of I-40 between Memphis and Nashville, which was designated as such by the Tennessee General Assembly in 1997. The act defines the designation as spanning "from the eastern boundary of Davidson County to the Mississippi River in Shelby County", a distance of about 222 miles (357 km). The designation commemorates the significant roles that Memphis, Nashville, and the areas in between played in the development of American popular music. Memphis is known as "the Home of the Blues and the Birthplace of Rock and Roll", and Nashville is known as "Music City" for its influence on numerous types of music, especially country. Several cities and towns between the two, including Jackson, Brownsville, Nutbush, Waverly, and others were birthplaces or homes of numerous singers and songwriters. Signs that display the words "Music Highway" along with musical notes are erected in both directions along I-40 throughout this section. In addition, the rest areas along this stretch are each named for musicians or bands associated with the respective locations, and contain related information.[20]

Prior to the settlement of Tennessee by European Americans, a series of Native American trails existed within what is now the Interstate 40 corridor. The Cumberland Trace, also known as Tollunteeskee's Trail, was a Cherokee trail that passed through the central part of the Cumberland Plateau, and was first used by settlers and explorers in the 1760s. In 1787, the North Carolina legislature, which at the time controlled what is now Tennessee, authorized the construction of a trail between the south end of Clinch Mountain near present-day Knoxville and the Cumberland Association, which included modern-day Nashville. Completed the following year, this trail became known as Avery's Trace, and roughly followed several existing Native American trails.[21] After the creation of the Southwest Territory, the territorial legislature authorized a wagon trail to be constructed between Knoxville and Nashville on July 10, 1795. This trail was officially named the Cumberland Turnpike, and became popularly known as the Walton Road after one of its surveyors, William Walton, a veteran of the American Revolutionary War. It was constructed out of portions of Tollunteeskee's Trail, Avery's Trace, and the Emery Road, and passed through the cities of Kingston, Carthage, and Gallatin. It was built between 1799 and 1801 at a cost of $1,000 (equivalent to $19,461 in 2020[22]).[23]

In 1911, a series of Tennessee businessmen formed the Memphis to Bristol Highway Association in an effort to encourage the state to improve the network of roads that ran between Memphis and Bristol.[24] After the formation of the Tennessee Department of Highways, the predecessor agency to the Tennessee Department of Transportation (TDOT), in 1915, the agency designated these roads as the Memphis to Bristol Highway and State Route 1.[6] When the United States Numbered Highway System was formed by Congress in 1926, the portion of this route between Memphis and Knoxville became part of US 70 and US 70S, and the part between Knoxville and Bristol was designated as part of US 11 and US 11W.[24][25][26] This highway became recognized as part of the "Broadway of America" highway between California and New York in the late 1920s.[27]

A 1953 map produced by The Knoxville News-Sentinel of the Magnolia Avenue Expressway. The cloverleaf interchange at right was used for the junction between I-40 and I-75.

The first completed segment of I-40 in Tennessee was a 1.09-mile (1.75 km) long freeway in Knoxville, which was jointly constructed by the state and local governments and was also the first freeway in Tennessee.[28][29] Known initially as the Magnolia Avenue Expressway and later renamed the Frank Regas Expressway, this freeway originated from a 1945 plan that recommended a number of expressways be constructed in Knoxville to relieve congestion on surface streets.[29][30] Planners intended these freeways to be integrated into the then-proposed nationwide highway network that became the interstate system, which at that time was expected to eventually be authorized by Congress.[31] The location and design of this freeway was finalized in a subsequent plan in 1948,[32][28] and preliminary construction began on October 1, 1951.[33] The first segment, between Unaka Street and Tulip Avenue, was completed on November 14, 1952,[34] and the second segment, between Tulip Avenue and Gay Street, was completed on December 10, 1955.[35] The Magnolia Avenue Expressway contained a cloverleaf interchange which was reused for the intersection with I-75 (now I-275) and US 441.[29][28] This configuration quickly developed a reputation for severe congestion and a high accident rate, and became known locally as "Malfunction Junction".[36][28]

The Tennessee leg of Interstate 40 was part of the original 1,047.6 miles (1,685.9 km) of Interstate Highways authorized for the state by the Federal-Aid Highway Act of 1956, commonly known as the Interstate Highway Act.[37] The numbering was approved by the American Association of State Highway Transportation Officials (AASHTO) on August 14, 1957.[3] At 451.8 miles (727.1 km) long, I-40 in Tennessee was initially planned as the longest segment of Interstate Highway within a single state east of the Mississippi River until an extension of I-75 in Florida was authorized by the Federal-Aid Highway Act of 1968.[38][3] The first design contract for I-40 in Tennessee was awarded on March 4, 1956, for a short section in Davidson County. Within a year, design contracts had been awarded for sections in Davidson, Knox, Roane, Haywood, Madison, Jefferson, and Cocke counties. By 1958, design work was underway for most of the entire route in Tennessee.[39]

A sign at a construction site for a segment of I-40 in Nashville in 1962 explaining the project[40]

The first contract for construction of Interstate 40 in Tennessee under the Interstate Highway System was awarded on August 2, 1957, for a 4.8-mile (7.7 km) section in Roane County between the Clinch River near Kingston and SR 58, and construction began the following month.[41][42] Construction on I-40 between Memphis and Nashville began on September 18, 1958, in Madison County near Jackson.[43] On October 19, 1961, the bridge over the Clinch River, constructed at a cost of $2.4 million (equivalent to $16.2 million in 2020[22]), was dedicated and opened to traffic by then-Governor Buford Ellington.[44] The 21.5-mile (34.6 km) section between US 70 east of Brownsville and US 70 in Jackson, referred to at the time as the "Jackson Bypass", was opened to traffic on December 1, 1961.[45] The following day, the 31-mile (50 km) segment between the Clinch River bridge in Kingston and Papermill Drive in Knoxville opened.[46][47] On October 31, 1962, the section between SR 113 near Dandridge and US 411/US 25W/US 70 in Newport was opened.[48] The first section of I-40 in Middle Tennessee to be completed was the 14.5-mile (23.3 km) stretch between SR 96 in Williamson County and US 70S in Bellevue, opened on November 1, 1962.[49][50] The next day, the 16.5-mile (26.6 km) segment between SR 56 near Silver Point and US 70N in Cookeville saw its first traffic.[51] The short segment between US 70S in Bellevue and US 70 in western Nashville was opened on November 15, 1962.[50]

The short segment between I-240/Sam Cooper Boulevard and US 64/US 70/US 79 (Summer Avenue), which was then part of I-240, was dedicated on October 9, 1963, by then-Governor Frank G. Clement, and opened to traffic 14 days later.[52][53] The 31-mile (50 km) stretch between SR 59 near Braden and US 70 east of Brownsville was dedicated and opened by Governor Clement on December 17, 1963.[54] On December 21, 1963, two sections, the 9-mile (14 km) segment between SR 46 in Dickson and SR 96 in Williamson County, and the 15-mile (24 km) segment between SR 53 in Gordonsville and SR 56 near Silver Point were opened.[55][56] The opening of the short stretch between Papermill Drive and Liberty Street in Knoxville was announced on September 4, 1964.[57] Two short noncontiguous sections, located between US 27 in Harriman and the Clinch River Bridge in Kingston, and between Liberty Street and Unaka Street in downtown Knoxville, respectively, were opened on December 4, 1964.[58][59] On December 14, 1964, two separate stretches; 23 miles (37 km) between I-240 in East Memphis and SR 59 in Braden, and 21 miles (34 km) between US 70 in Jackson and SR 22 in Parkers Crossroads, were dedicated by Governor Clement.[60] The short stretch between Fesslers Lane and Spence Lane in Nashville, including the eastern interchange with I-24, was declared complete on January 11, 1965.[61] The short stretch between the western interchange with I-24 and Fesslers Lane was partially opened in late December 1963, along with the nearby Silliman Evans Bridge,[62] and fully opened on April 19, 1965.[63]

Work began on the bridge over the Tennessee River on November 29, 1962, and was completed on July 21, 1965, at a cost of $4.62 million (equivalent to $29.5 million in 2020[22]).[64] Multiple short segments of the western portion of the 26-mile (42 km) stretch between Spence Lane in Nashville and US 70 in Lebanon were opened to local traffic throughout 1963;[65][62] dedication of this entire stretch by Governor Clement occurred on August 26, 1965.[66][67] The 10.5-mile (16.9 km) segment between SR 13 in Humphreys County and SR 230 in Hickman County was completed on November 24, 1965.[64] On December 20, 1965, four segments were declared complete. These were the 19-mile (31 km) stretch between US 70 in Lebanon and SR 53 in Gordonsville, the 8-mile (13 km) segment between the Tennessee River and SR 13 in Humphreys County, the 11-mile (18 km) stretch between US 70N in Cookeville and US 70N in Monterey, and the 3-mile (4.8 km) segment between US 411/US 25W/US 70 and US 321 in Cocke County.[68][69] On July 24, 1966, I-40 was completed between Memphis and Nashville, with the dedication of the 64-mile (103 km) segment between SR 22 in Parkers Crossroads and SR 46 near Dickson in a large ceremony on the Tennessee River Bridge officiated by Governor Clement and U.S. Senator Albert Gore Sr.[70][71] This was the first interstate highway segment completed between two major cities in Tennessee, and cost $109.87 million (equivalent to $683 million in 2020[22]).[72][43]

In December 1966, the segment between US 25W/70 and SR 113 in Jefferson County, including the interchange with I-81, was completed.[73][74] On April 11, 1967, the short segment between Gay Street and US 11W in Knoxville was opened.[75][76] The 16-mile (26 km) segment between US 70N in Monterey and US 127 in Crossville was opened to traffic on December 1, 1967.[77] The final section of I-40 in Knoxville to be completed was the short segment between US 11W and US 11E/25W/70, which opened on December 19, 1967, to eastbound traffic,[78] and to westbound traffic on June 21, 1968.[79] The 12-mile (19 km) long segment between US 127 in Crossville and US 70 in Crab Orchard was opened on September 12, 1968.[80] On September 26, 1969, the section between US 70 in Crab Orchard and SR 299 near Westel Springs was opened.[81] The section through the Pigeon River Gorge in Cocke County, as well as into North Carolina, was initially believed by some engineers to be impossible to construct. Construction of this segment was one of the most difficult and laborious highway projects in the nation, requiring thousands of tons of earth and rock to be moved.[82] It was also one of the most expensive highway construction projects per mile, at a cost of $19 million (equivalent to $110 million in 2020[22]).[83][84] Work began on this project in 1961,[84] and the entire stretch, 37 miles (60 km) between US 321/SR 32 in Newport and US 276 in Haywood County, North Carolina, was jointly opened to traffic on October 24, 1968, by both states in a dedication ceremony.[85]

The short segment between 46th Avenue in West Nashville and the interchange with I-65 in North Nashville opened to traffic on March 15, 1971.[86] In Memphis, the short stretch between US 51 and Chelsea Avenue, including the Midtown interchange with I-240 (then I-255) opened on July 14, 1971.[87] Work on the final segment between Memphis and Knoxville, approximately 5.5 miles (8.9 km) between the interchange with I-65 in North Nashville and the split with I-24 southeast of downtown Nashville, including the concurrency with I-65, began in May 1969 and was opened on March 3, 1972. This completed the entirety of I-40 between Memphis and SR 299 near Rockwood, as well as the last stretch in Middle Tennessee.[88] The last segment of the original planned route of I-40 in West Tennessee to be completed was the Hernando de Soto Bridge in Memphis; construction began on May 2, 1967, and the bridge opened to traffic on August 2, 1973.[89][90] The bridge, which cost $57 million (equivalent to $259 million in 2020[22]), was dedicated in a ceremony by Tennessee Governor Winfield Dunn and Arkansas Governor Dale Bumpers on August 17, 1973.[91][92]

The 9-mile (14 km) segment between SR 299 and US 27 near Harriman and Rockwood, including the descent up Walden Ridge, was opened to traffic on August 19, 1974, after years of delays due to geological problems, completing the entirety of the route between Memphis and Knoxville.[93] Work started on this section in early 1966, and was originally expected to be complete by late 1968.[94] The final segment of the planned route of I-40 in Tennessee, 21.5 miles (34.6 km) located between US 11E/25W/70 east of Knoxville and US 25W/70 in Dandridge, was dedicated by Governor Dunn and partially opened to traffic on December 20, 1974,[95][96] and fully opened on September 12, 1975.[4] Initially planned to carry four lanes, engineers chose to expand this segment to six lanes in 1972 after construction had already begun, based on studies projecting higher-than-average traffic volumes.[97] As a result, this segment was one of the first rural six-lane highways in the country, and was also dedicated on the same day that the last sections of I-75 and I-81 in Tennessee were opened.[95][98] The last section of what is now I-40 in Tennessee to be completed was the section between Chelsea Avenue and US 64/70/79, which was originally part of I-240. Construction began in April 1974, and the section was opened to traffic by Governor Lamar Alexander on March 28, 1980, after years of delays.[99]

1955 Bureau of Public Roads plan for interstates in Memphis. I-40 (center) was originally planned to pass through Overton Park, but was never built due to citizen opposition.

In Memphis, I-40 was originally slated to pass through the city's Overton Park, a 342-acre (138 ha) public park. This location was announced in 1955 and subsequently approved by the Bureau of Public Roads, the predecessor to the Federal Highway Administration (FHWA), the following year.[100] The park consists of a wooded refuge, as well as the Memphis Zoo, the Memphis Brooks Museum of Art, the Memphis College of Art, a 9-hole golf course, an amphitheater that was the site of Elvis Presley's first paid concert in 1954, and other features. When the state announced plans to route I-40 through the park, a group of local citizens, spearheaded by a group of elderly women dubbed the "little old ladies in Tennis shoes" by multiple media outlets, began a campaign to stop this construction. The organizers first collected over 10,000 signatures in their support, and founded the organization Citizens to Preserve Overton Park in 1957.[101] The movement was also backed by environmentalists, who feared that the interstate's construction would upset the park's fragile ecological balance, as the wooded area had become an important stopover for migratory birds.[102]

The organization waged a multi-year effort to prevent construction of the highway in the park, and filed a lawsuit the Western District Court of Tennessee in December 1969 after then-U.S. Secretary of Transportation John Volpe had authorized the state to advertise bids for the route the previous month.[103] The court ruled against them, which was subsequently upheld by the Sixth Circuit Court of Appeals on September 29, 1970.[104] The case was then appealed to the United States Supreme Court, which on March 2, 1971, ruled in favor of them in the landmark decision of Citizens to Preserve Overton Park v. Volpe. The Supreme Court remanded the case to the District Court for further review, and ruled that the highway commission had not adequately explored alternative routes.[105] For many years after this decision, the state continued to explore options to route I-40 through Overton Park, including tunneling under the park or constructing the highway below grade, but ultimately concluded that these alternatives were too expensive.[100] On January 9, 1981, then-Governor Alexander submitted a request to the then-Secretary of Transportation Neil Goldschmidt to cancel the route through Overton Park, which was approved seven days later.[106][107]

Immediately after the cancellation of the Overton Park section, the northern portion of I-240 was redesignated as the remainder of I-40, adding approximately 3.5 miles (5.6 km) to the route.[2] About four miles (6.4 km) of a controlled-access highway was actually built within the I-240 loop east of the park; this portion of highway still exists and is in regular use as Sam Cooper Boulevard, terminating at East Parkway in the Binghampton neighborhood near the park. For over 20 years, I-40 signage remained on this segment.[102] In addition, right of way was acquired west of the park, and many structures demolished to make way for the interstate. Most of these empty lots have since been built over.[108] At the time of the route's cancellation, approximately $280 million (equivalent to $688 million in 2020[22]) had been budgeted by the federal government for its construction; these funds were then diverted for other transportation improvements in the Memphis metropolitan area.[108][107]

In western Nashville, I-40 passes through the Jefferson Street community, a predominantly African American neighborhood, which contains three historically Black colleges and was a site of the Nashville sit-ins during the civil rights movement.[109] This section was originally slated to pass near Vanderbilt University until the mid 1960s.[110] While still in the planning phase, many residents opposed its routing, believing that it would divide their community from the rest of the city and lead to economic decline of the neighborhood. Some also believed that the routing was an act of racial discrimination. In October 1967, several residents of Jefferson Street, organized as the I-40 Steering Committee, began legal action against the state in an effort to force them to reroute I-40. The Davidson County General Sessions Court ruled against the organization, arguing that there was no alternate route for the interstate and that the residents were exaggerating the effect of the damage that it would have. The I-40 Steering Committee appealed the decision to the Sixth Circuit Court of Appeals, which ruled unanimously against them on January 29, 1968, but did concede that the methods the state used to notify residents about the project were unsatisfactory.[111] The committee appealed the ruling to the U.S. Supreme Court, which refused to hear the case. The construction of I-40 through Jefferson Street ultimately resulted in many Black residents being displaced to the Bordeaux area in North Nashville, and did lead to the deterioration of the neighborhood that had been predicted.[112]

The interchange between I-40 and I-240 in Midtown Memphis in 2003, shortly before reconstruction. Unused ramps and bridges and grading for the cancelled section of I-40 (right) are visible.

The first HOV lanes in the Memphis area opened on September 15, 1997, on the 7.5-mile (12.1 km) section between I-240 and US 64 in Bartlett with the completion of a project that widened this segment from four to eight lanes.[113]

The cancellation of the section of I-40 through Overton Park rendered both interchanges with I-240 inadequate to handle the unplanned traffic patterns, thus necessitating their reconstruction.[108] In addition, both interchanges contained ramps with hazardously sharp curves with some of the highest crash rates in the state.[114] On the eastern interchange, reconstruction was accomplished in two separate projects.[115] The first project, which began in January 2001 and was completed in October 2003, constructed a new two-lane flyover ramp from I-40 westbound to I-240 westbound, replacing a single-lane loop ramp, and widened the approach of I-240 south of the interchange.[116][117] Also in this project, I-40 directly north of the interchange was reconstructed in preparation for the second project and the interchanges with US 64/70/79 (Summer Avenue) and White Station Road were modified.[115]

The second project was initially slated to begin in January 2004,[115] but was delayed until October 2013 due to funding and redesign complications.[118] A two-lane flyover was constructed to carry I-40 eastbound traffic through the interchange, replacing a one-lane ramp. The single-lane ramp carrying I-40 westbound traffic through the interchange was rerouted to become the exit ramp for Summer Avenue and replaced with a two-lane flyover that connects to the flyover constructed in the first project. Additional aspects of this project widened the ramp between I-240 eastbound and I-40 eastbound to three lanes, widened both approaches to the interchange on I-40, which required a new 14-lane bridge over the Wolf River, widened the approach on I-240 south of the interchange, added through lanes to Sam Cooper Boulevard, and reconfigured the SR 204 (Covington Pike) interchange.[119] The project cost $109.3 million, which was at the time the highest-bid contract in state history,[118] and was completed on December 15, 2016.[120]

The interchange with the western terminus of I-240 near Midtown Memphis was reconstructed between June 2003 and December 2006.[121] This project consisted of converting the interchange into a directional T interchange and the demolition of several unused ramps and bridges that had been constructed with the intent of I-40 continuing directly east of this interchange prior to the Overton Park controversy.[122] The nearby cloverleaf interchange with SR 14 (Jackson Avenue) was also reduced to a partial cloverleaf interchange, and several additional auxiliary lanes and slip ramps were constructed. The northern merge with I-40 and I-240 was moved north of the SR 14 interchange.[123]

I-40 near Mt. Juliet, a suburb of Nashville

In November 1977, TDOT installed a system to detect tailgating vehicles in the westbound lanes of the concurrent segment with I-24, which consisted of sensors embedded in the roadway connected to overhead warning signs with flashing lights and horns.[124][125] The system was the first of its kind in the country, but experienced technical problems and was criticized as ineffective, leading to its decommission in July 1980.[126] This segment of I-40 was widened from six to eight lanes between July 1979 and January 1980 by removing the right shoulders, narrowing the lanes by one foot (0.30 m), and shifting traffic slightly to the left.[127][128]

The short segment of I-40 between east of the split with I-24/440 and east of SR 255 (Donelson Pike) in eastern Nashville was widened to six lanes between August 1986 and December 1987.[129] Between October 1987 and November 1989, the 4.7-mile (7.6 km) segment between east of SR 255 and east of SR 45 was widened to six lanes.[130] West of downtown Nashville, the 3-mile (4.8 km) section between SR 155 (Briley Parkway, White Bridge Road) and US 70 (Charlotte Pike) was expanded to six lanes between February 1988 and December 1989. Between April 1991 and December 1992, the section between US 70 and US 70S in Bellevue, a distance of 5.9 miles (9.5 km), was widened to six lanes.[131]

The first HOV lanes on I-40 in Tennessee were opened to traffic on November 14, 1996, with the completion of a project that widened the 8-mile (13 km) section between west of SR 45 (Old Hickory Boulevard) in eastern Nashville and east of SR 171 in Mt. Juliet from four to eight lanes.[132] These were the second set of HOV lanes constructed in Tennessee.[133] This project, which began in early 1995, was also the first in Tennessee to be constructed with split Jersey barriers in the median every few miles to allow police enforcement from the left shoulders.[134] The short stretch between SR 155 (Briley Parkway/White Bridge Road) and the western terminus of I-440 was modified in a project between November 2002 and July 2005 that widened the stretch to eight through lanes, added auxiliary lanes, improved and expanded access between multiple local thoroughfares, and added partial access control between the southern end of Briley Parkway by means of two new flyover ramps.[135][136] The second phase, which ran between July 2009 and August 2011, constructed an additional flyover ramp between I-40 and Briley Parkway, converting the interchange to full access control, further modified the White Bridge Road interchange, and widened a short stretch of I-40 west of this interchange.[137][138]

A project which ran between January 2004 and January 2007 widened the 3-mile (4.8 km) section between I-24/440 and SR 255 from four to eight through lanes, added extra auxiliary lanes between interchanges, and reconstructed the interchange with SR 155 (Briley Parkway) into a fully controlled-access interchange.[139][140] Work to widen six miles (9.7 km) of I-40 from four to eight lanes between east of SR 171 and east of SR 109 in Lebanon began in July 2012 and was completed in July 2014.[141][142] The 4-mile (6.4 km) stretch between east of SR 109 and east of I-840 in Lebanon was widened from four to eight lanes between April 2019 and September 2021.[143][144]

An aerial view of "Malfunction Junction" prior to its reconstruction, looking north

Beginning in early May 1980, the segment of I-40 in Knoxville between Papermill Road and Gay Street was modified in a project that eliminated the interchanges with 17th Street, Western Avenue, and Gay Street, widened the segment to a minimum of three through lanes in each direction, added frontage roads, and reconstructed the gridlock-prone cloverleaf interchange with I-75, known as "Malfunction Junction", into a stack interchange with flyover ramps.[145][146] The noncontiguous segment between US 11W (Rutledge Pike) and US 11E/25W/70 (Asheville Highway) was also widened to six lanes.[147] The project was completed on March 30, 1982, in a ceremony officiated by Governor Lamar Alexander.[148] While these projects were underway, the concurrent part of I-75 on this segment was rerouted around the western leg of I-640, which was completed in December 1980, and the short segment of I-75 north of this segment became I-275.[149] These projects were conducted as part of a larger $250 million (equivalent to $579 million in 2020[22]) multi-phase improvement project on multiple roads in the area that was accelerated in preparation for the 1982 World's Fair.[150][151]

By the mid-1970s, the concurrent segment of I-40 with I-75 between Lenoir City and western Knoxville had begun to experience congestion problems, and in 1978 the FHWA authorized TDOT to widen the segment between the I-75 interchange near Lenoir City and the Pellissippi Parkway to six lanes and the segment between the Pellissippi Parkway and I-640 to eight lanes, as well as reconstruct interchanges along this segment. TDOT announced plans to proceed with the project in May 1981; however, they initially chose to only widen the entire segment to six lanes, due to the need for immediate congestion relief and the fact that the larger project required additional right of way.[152] The six-lane project began in July 1984 with the segment between Papermill Road and the Pellissippi Parkway, and this was completed in December 1985.[153] The remainder of the project, located between the Pellissippi Parkway and the I-75 split, took place between June 1985 and July 1986.[154]

On October 9, 1986, the FHWA approved an environmental impact statement for the remainder of the I-40/75 improvement project, which was extended two miles (3.2 km) west to SR 131.[152] The first phase, which was accomplished in two separate contracts between August 1990 and August 1994, widened the section between east of the Pellissippi Parkway and east of Cedar Bluff Road, and reconstructed the interchange with Cedar Bluff Road.[155][156] In preparation for the second phase, Gallaher View Road was extended north to the interstate between April 1994 and July 1996, with a new overpass over the interstate and on-ramp constructed.[157][158] The second phase, which ran from May 1996 to December 1999, widened the section between east of Cedar Bluff Road and east of Gallaher View Road and extended Bridgewater Road to the interstate.[159][160] The interchange with Walker Springs Road was replaced with a new interchange providing access to all three roads via collector-distributor frontage roads in between.[157] The third phase, which occurred between early 2000 and late 2002, widened the segment between Papermill Road and I-640 from six to ten lanes. The fourth phase, which ran from September 2000 to July 2003, improved the interchange with SR 131 and widened the section between this route and the Pellissippi Parkway.[161] The final phase, which occurred between January 2003 and December 2006, widened the section between Gallaher View Road and Papermill Road, and reconfigured the interchanges with the US 11/70 connector and Papermill Road.[162][163] A new collector-distributor facility serving the westbound ramps was built along the Papermill interchange, and ramps providing direct access to Weisgarber Road and SR 332 were constructed.[164]

Starting with preliminary engineering in 1995,[165] TDOT undertook a $203.7 million project called "SmartFix 40" on the segment between I-275 and Cherry Street. The first phase, which was largely divided into two sub-phases, took place between July 6, 2005, and September 21, 2007.[166] It consisted of reconstructing and realigning the interchanges with SR 158 (James White Parkway), Hall of Fame Drive, and Cherry Street, and constructing collector-distributor ramps between these interchanges.[167][168] For the second phase, I-40 between SR 158 and Hall of Fame Drive was completely closed to all traffic between May 1, 2008, and June 12, 2009.[169] This section, which was four lanes between east of I-275 and SR 158 and six lanes between SR 158 and Cherry Street, was widened to six and eight lanes, plus additional auxiliary lanes. This substandard section had been a severe bottleneck, and was highly accident-prone. In addition, left-hand entrance and exit ramps with the SR 158 interchange were eliminated.[170] During this closure, through traffic was required to use I-640 or surface streets, and inbound and outbound ramps between I-40 and I-640 at both interchanges were temporarily widened to three lanes to facilitate the extra traffic.[171] Both phases of SmartFix 40 won an America's Transportation Award from AASHTO in 2008 and 2010, respectively.[172][173] As of 2022, SmartFix 40 was the largest project ever coordinated by TDOT, and one of only two of its kind attempted in the United States.[174]

High-altitude view of the Tennessee River looking north, with I-40 at the bottom and the Jimmy Mann Evans Memorial Bridge in the bottom left

Between July 1997 and November 1999, the 6-mile (9.7 km) section between US 25W/70 and I-81 in Jefferson County was widened to six lanes.[175]

A 2008 study conducted by TDOT on the I-40 and I-81 corridors identified a number of steep grades difficult for trucks to ascend, causing congestion and safety hazards. This resulted in TDOT constructing truck climbing lanes throughout the corridor. In 2018, a 2-mile (3.2 km) long westbound truck lane immediately west of the Tennessee River in Benton County and a 2-mile (3.2 km) westbound truck lane in Humphreys and Hickman counties were completed.[176][177] The following year, two additional projects, a 4-mile (6.4 km) lane in Dickson and Williamson counties and a 3-mile (4.8 km) lane in western Smith County, both in the eastbound direction, were completed. In 2020, the most recent truck lane was completed on a 2-mile (3.2 km) segment of the eastbound lanes in eastern Cumberland County.[178]

In Jackson, TDOT is working to widen I-40 to six lanes and improve interchanges in three separate phases. The first phase, which began on October 2, 2017, widened I-40 between west of the US 45 Byp. and east of US 45, a distance of approximately 2.9 miles (4.7 km); added auxiliary lanes between these interchanges and the interchange with US 412, converted the cloverleaf interchange with the US 45 Byp. into a partial cloverleaf interchange and the cloverleaf with US 70 into a single point urban interchange (SPIU), and replaced bridges and improved intersections on both routes near the interchanges.[179][180] The entire first phase was completed in early July 2021.[181] The second phase, which began on November 4, 2020, widens I-40 from east of US 45 to east of US 70/US 412, a distance of approximately 5.5 miles (8.9 km), adds auxiliary lanes, and replaces multiple bridges along this segment. It is expected to be completed by November 8, 2022.[182] The final phase, which began on July 10, 2022, and is expected to be completed by May 31, 2024, widens the 1.2-mile (1.9 km) segment from west of US 412 to west of US 45 Byp.[183][184]

The rugged terrain of East Tennessee presented numerous challenges for I-40 construction crews and engineers. Rockslides, especially along the eastern Cumberland Plateau and in the Pigeon River Gorge, have been a persistent problem since the road's construction.[185]

On December 17, 1986, a truck driver was killed when his truck skidded across rocks that had fallen across the road just east of Crab Orchard between miles 331 and 333.[186] In response to this incident, between January 1987 and December 1988, TDOT flattened the cutslopes along this stretch of interstate and moved the road 60 feet (18 m) away from the problematic cliffside.[187][185]

Twenty rockslides occurred along the Walden Ridge section, miles 341–346, of the eastern plateau in 1968 alone, while still under construction. This prompted various remedial measures throughout the 1970s, including the employment of rock buttresses, gabion walls, and horizontal drains.[185] A minor rockslide shut down the right lane of westbound I-40 at mile 343 on May 6, 2013.[188]

An area very prone to rockslides is the Pigeon River Gorge, especially in the vicinity of the Tennessee–North Carolina state line.[189] Throughout the 1970s, this stretch of I-40 was repeatedly shut down by rockslides, sometimes for several weeks at a time. In the late 1970s and early 1980s, TDOT dug over 24,000 feet (7,300 m) of horizontal drains, blasted out large volumes of unstable rocks, and installed massive mesh catchment fences.[185] Nevertheless, rockslides in 1985 and 1997 again forced the closure of I-40 in the Pigeon River Gorge for several weeks.[190] Additional stabilization measures were implemented, including the blasting of loose rock, the installation of rock bolts, and the construction of a better drainage system.[191] In spite of these measures, another massive rock slide occurred in the Pigeon River Gorge on October 26, 2009, blocking all lanes just across the border at North Carolina mile 3. The section was closed to traffic in both directions until April 25, 2010.[192] On January 31, 2012, the westbound lanes of I-40 were closed because of a rockslide near the North Carolina border. Traffic was detoured along I-26 and I-81 and reopened a few months later.[193]

Sinkholes are a consistent issue along highways in East Tennessee. One particularly problematic stretch is a section of I-40 between miles 365 and 367 in Loudon County, which is underlain by cavernous rock strata. In the 1970s and 1980s, TDOT employed numerous stabilization measures in this area, including backfilling existing sinkholes with limestone, collapsing potential sinkholes, and paving roadside ditches to prevent surface water from seeping into the volatile soil.[185]

On December 23, 1988, a 10,450-US-gallon (39,600 l) tanker truck hauling liquified propane overturned along a one-lane ramp carrying I-40 traffic through the Midtown interchange with I-240 in Memphis, rupturing a small hole in the front of the tank.[194][195] The leaking gas ignited in a boiling liquid expanding vapor explosion (BLEVE) seconds later, producing a massive fireball that set nearby vehicles and structures on fire and instantly killed five motorists, including the driver.[196][197] The tank was then propelled from the crash site by the remaining escaping combusting gas, causing it to strike a nearby overpass bridge, bounce off the ground, and crash into a duplex apartment about 125 yards (114 m) away. This killed one occupant and started additional fires which subsequently spread to multiple other buildings and cars.[198] A total of seven additional cars were destroyed, and ten cars, six houses, and one additional residential complex were damaged by the explosion and subsequent fires.[196] 10 people were injured, and two people who were inside of homes impacted by the fires later died from their injuries.[199] A truck driver was also killed when he crashed into a traffic jam caused by the accident.[200] This accident was one of the deadliest and most destructive motor vehicle accidents to ever occur in Tennessee, and provided momentum for the eventual reconstruction of the interchange.[121]

On May 11, 2021, inspectors discovered a crack on a tie girder of the Hernando de Soto Bridge, resulting in closure of the bridge to all traffic.[201] A subsequent investigation revealed that the crack had existed since at least May 2019, and reports later surfaced that the crack had likely existed since August 2016.[202][203] TDOT awarded an emergency repair contract for the bridge on May 17, 2021, that was conducted in two phases.[204][205] In the first phase, which was completed on May 25, 2021, fabricated steel plates were attached to both sides of the fractured beam.[206] The second phase consisted of the installation of additional steel plating and removal of part of the damaged beam.[204] The eastbound lanes of the bridge reopened on July 31, 2021,[207] and the westbound lanes reopened on August 2, 2021.[208]