Construction of the controlled-access highway began in the 1950s, and, by the late 1970s, most of the freeway across the state of Utah had been completed. The 4.5-mile-long (7.2 km) section of I-80 between State Route 68 (SR-68, Redwood Road) and Salt Lake City International Airport was the last piece of the nearly 2,900-mile-long (4,700 km) freeway to be completed. It was opened on August 22, 1986, and was about 50 miles (80 km) from the site of another cross-country milestone in Utah, the driving of the golden spike of the first transcontinental railroad at Promontory Summit. Average daily traffic volumes in 2012 ranged between 6,765 vehicles using the freeway at SR-58 and 121,205 vehicles using the freeway at the Spaghetti Bowl in Downtown Salt Lake City. Throughout the state, the highway is also known as the Purple Heart Trail.
Route description
Out of the 11 states which I-80 passes through, the 197.51-mile-long (317.86 km) segment in Utah is the fourth shortest. As part of the Interstate Highway System,[2] the entire route is listed on the National Highway System, a system of roads that are important to the nation's economy, defense, and mobility.[3]
Every year, the Utah Department of Transportation (UDOT) conducts a series of surveys on its highways to measure traffic volumes. This measure is expressed in terms of annual average daily traffic (AADT), a measure of traffic volume for any average day of the year. In 2012, UDOT calculated that as few as 6,765 vehicles traveled I-80 at the interchange with SR-58 in Wendover, and as many as 121,205 vehicles used the highway at the Spaghetti Bowl in Downtown Salt Lake City.[4] Between 7 and 58 percent of the traffic recorded consisted of trucks.[5] These counts are for the portion of the freeway in Utah.
Bounded on each sides by military training grounds,[13] the I-80 corridor is overflown by commercial airliners traveling west from Salt Lake City International Airport.[14] The freeway veers north around the Cedar Mountains in a small gap between them and the Lakeside Mountains. Further east, the highway passes the Stansbury Mountains, which are located in the Wasatch–Cache National Forest.[15] After the mountain ranges, the freeway arrives at the southern shore of the Great Salt Lake and closely follows the shore toward the western suburbs of Salt Lake City.[16] However, the historical routes from which the route of I-80 was derived were routed further from the lake, passing through the towns of Grantsville and Tooele; these communities are now served by SR-138 and SR-36, respectively.[7] It is in this section that I-80 reaches its lowest elevation in Utah, 4,203 feet (1,281 m) above sea level.[17] After an interchange with SR-36 at Lake Point, the highway crosses a bottleneck between the Oquirrh Mountains and the Great Salt Lake.
Salt Lake County
While traversing the neck, views can be had from I-80 of the lake and Antelope Island. After passing the neck, the road forks, with I-80 proceeding toward the north end of Salt Lake City and SR-201 proceeding toward the south end.[18] Historically, this intersection was the separation of US-40 and US-50. After the intersection, the freeway corridor is again bottlenecked with the Great Salt Lake to the north and the Kennecott Utah Coppersmelter and tailings pond to the south. The Kennecott Utah Copper's Bingham Canyon Mine, which was once considered to be the largest open-pit copper mine, can be seen in the distance.[19] The 1,215-foot-tall (370 m) Kennecott Garfield Smelter Stack is one of the tallest freestanding structures in the United States.[20] Along this portion, the freeway passes the historical site of Saltair.[7]
The freeway enters the Salt Lake Valley on the former alignment of North Temple Street until it passes Salt Lake City International Airport, where the freeway veers slightly south and leaves the North Temple Street corridor which leads to Temple Square in Downtown Salt Lake City. The Green Line of the Utah Transit Authority (UTA) TRAX system briefly parallels I-80 before traveling down the center of North Temple Street. I-80 becomes concurrent with I-15 after interchanges with SR-68 and 600 South and continues south for about three miles (4.8 km), passing along the western and southern edges of Downtown Salt Lake City. The southern interchange with I-15, which also includes SR-201 (21st South Freeway) and marks the end of the concurrency, is known as the Spaghetti Bowl.[21] In the southwestern corner of the Spaghetti Bowl is another portion of the UTA TRAX Green Line as it travels towards West Valley City. After separating from I-15, the freeway continues easterly through South Salt Lake, loosely following an alignment just south of 2100 South and the UTA S Linestreetcar through the Sugar House neighborhood and past Sugar House Park—once the home of the Sugar House Prison[22]—toward the clockwise terminus of the I-215 270-degree beltway around Salt Lake City. It continues through Parleys Canyon,[7] where the freeway joins the historical route of the Lincoln Highway.[23] Between the mouth of the canyon and the Summit County line, the route reenters the Wasatch National Forest.[18]
Summit County
Parleys Canyon carries I-80 up the eastern slope of the Wasatch Front as a six-lane freeway,[7] cresting the mountains at an elevation of 7,016 feet (2,138 m) at Parleys Summit, the highest point on I-80 within the state of Utah.[24] Both the canyon and summit were named for Parley P. Pratt, an early settler to the Salt Lake Valley and an early Mormon leader who was asked to survey a new route across the mountains to replace the route through Emigration Canyon. Between 1848 and 1851, Pratt surveyed, completed, and operated the Golden Pass toll road through the canyon that today bears his name. Pratt had unsuccessfully solicited for $800 (equivalent to $22,801 in 2023[25]) to build the road and sold it for $1,500 (equivalent to $43,668 in 2023[25]).[26] On- and offramps for the Wyoming port-of-entry are located just within Utah.[7] In January 2014, UDOT introduced variable speed limits to I-80 in Parleys Canyon, allowing a speed limit between 35 mph (56 km/h) up to the normal 65 mph (105 km/h) depending on weather or traffic conditions.[27]
Beyond Parleys Summit lies Park City, a mining town today better known for its many ski resorts.[28][29] The Historic Union Pacific Rail Trail State Park travels in the median between carriageways of I-80 before paralleling the highway until the southern end of Echo Reservoir.[30] The freeway turns north upon reaching the Rockport Reservoir at Wanship[31] following the tributaries of the Weber River toward Echo Reservoir and Dam. Upon reaching Echo Canyon and the junction with the eastern terminus of the western section of I-84, the freeway follows the canyon east until it reaches the Wyoming state line near Evanston. I-80 forms the northeastern border between Rich and Summit counties.[32]
The portion through Echo Canyon follows the historical routes of the Mormon Trail, US-30S, and the first transcontinental railroad.[33] A rest area in the canyon just east of the junction with I-84 features signs pointing out features that were obstacles for both the Mormon pioneers and the railroad construction workers, including Pulpit Rock,[34] which was partially demolished when the I-80 was built through the canyon.[35]
I-80 follows the routes of two major auto trails through the state. In western Utah, I-80 follows the historical route of the Victory Highway from Wendover at the Nevada state line to the junction of US-40 near Park City. Throughout Utah, I-80 is signed as the modern route of the Lincoln Highway—except through Salt Lake City, where the Lincoln Highway is routed along SR-201 and Parley's Way. The route of the Lincoln Highway across Utah was generally derived from the route of the Pony Express and Central Overland Route. However, much of the original route of the Lincoln Highway west of Salt Lake City is inaccessible. The original route of the Lincoln Highway proceeded southwest from Tooele toward Ely, Nevada. This area is now used for military bases, such as the Dugway Proving Ground and Tooele Army Depot. The area was closed to the public when these bases were established. I-80 and US-93 are the modern signing of the Lincoln Highway between those two cities. East of Salt Lake City, I-80 closely parallels the original route of the Lincoln Highway.[36][37]
In 1926, much of the route covered by I-80, including Pratt's former toll road from the Nevada state line into Salt Lake City, was signed as US-40 then as US-30 to the Wyoming state line.[38][39] It was also part of the Victory Highway west of Salt Lake and the Lincoln Highway east of Salt Lake at this time. Most of the route had been improved but some stretches of graded road remained.[40] In 1937, parts of the route near Wanship were numbered US-530.[41] In 1950, the highway near Echo was designated US-30S and US-189.[42] By 1959, US-50 Alternate (US-50 Alt) was also routed along the western portion of I-80.[43]
Current road
The first Utah state route to have the number 80 is now known as SR-92, which was originally numbered SR-80 until the 1977 Utah state route renumbering. Previously, the freeway's legislative designation was SR-2.[44]
Passage of the Federal-Aid Highway Act of 1956 formed the Interstate Highway System,[45] and the I-80 number was first designated to a then-unconstructed controlled-access highway across the state by 1957.[46] I-80 was constructed in segments, starting in the late 1950s. By the late 1970s, the Utah portion of I-80—except for a gap on the western edge of Salt Lake City—was largely complete. A 4.5-mile-long (7.2 km) section between Redwood Road and Salt Lake City International Airport is the final link of the transcontinental freeway to be completed.[47] As an Interstate Highway, design specifications require a controlled-access highway with no at-grade intersections. This section was dedicated on August 22, 1986, and was the last to be completed to Interstate Highway specifications along the almost 2,900-mile-long (4,700 km) route of I-80 between San Francisco, California, and Teaneck, New Jersey.[48] The section was completed close to the 30th anniversary of the Interstate Highway System, which was noted at the dedication and considered to be a milestone in the history of highway construction in the United States.[47] It was also noted at the dedication that this was only 50 miles (80 km) south of Promontory Summit, where the golden spike of the US's first transcontinental railroad was laid.[49]
Rebuilding of the first portions of I-80 began in October 1990 with a 1.4-mile-long (2.3 km) stretch near Redwood Road in Salt Lake City.[50] By 1991, UDOT estimated that the reconstruction of all federally funded highways in the state would cost up to $4.3 billion (equivalent to $8.58 billion in 2023[25]).[51]
Plans for the Spaghetti Bowl were announced in 1996. It was needed to accommodate traffic for the 2002 Winter Olympics being held in the city.[52] Most of the Spaghetti Bowl was open by November 2000; the remainder opened in early 2001.[53]
Additional reconstruction work—which involved the replacement of most of the bridges along the route and the resurfacing and installation of sound barriers—was done on I-80 between the Spaghetti Bowl and Parleys Canyon from 2007 to 2008.[56]
Part of the Spaghetti Bowl interchange; eastbound exit and westbound entrance; accessible from C/D lanes eastbound; westbound entrance includes direct entrance ramp from 900 West and direct entrance ramp to 1300 South/900 South
Westbound exit and eastbound entrance; signed as exits 123A (SR-201) and 123B (I-15) westbound; part of the "Spaghetti Bowl" interchange; I-15 exit 304
^Utah Department of Transportation (2012). Truck Traffic on Utah Highways (Report). Utah Department of Transportation. pp. 14–15. Archived from the original(PDF) on September 2, 2015. Retrieved December 25, 2013.
^Utah Department of Transportation (2005). "Tooele County" (Map). General Highway Map. 1:29,040. Salt Lake City: Utah Department of Transportation. p. 5. Retrieved December 26, 2013.
^California-Oregon-Washington Tourist Association (1927). Copyrighted Official Map (Map) (701 ed.). California-Oregon-Washington Tourist Association. Archived from the original on December 26, 2013. Retrieved December 26, 2013.
^Benchmark Maps (2002). Utah Road and Recreation Atlas (Map) (2002 ed.). 1:250000. Benchmark Maps. p. 40. § G1-12. ISBN0-929591-74-7.
^Utah Department of Transportation (2005). "Tooele County" (Map). General Highway Map. 1:29,040. Salt Lake City: Utah Department of Transportation. p. 6. Retrieved December 26, 2013.
^Federal Aviation Administration; AeroNav Products (October 17, 2013). Salt Lake City — South (Map) (90 ed.). Sectional Raster Aeronautical Charts. Federal Aviation Administration.
^Utah Department of Transportation (2005). "Tooele County" (Map). General Highway Map. 1:29,040. Salt Lake City: Utah Department of Transportation. p. 7. Retrieved December 26, 2013.
^Utah Department of Transportation (2005). "Tooele County" (Map). General Highway Map. 1:29,040. Salt Lake City: Utah Department of Transportation. p. 8. Retrieved December 26, 2013.
^ abUtah Department of Transportation (2005). "Salt Lake County" (Map). General Highway Map. 1:22,440. Salt Lake City: Utah Department of Transportation. Retrieved December 26, 2013.
^Utah Department of Transportation (2011). Official Highway Map (Map). Scale not given. Salt Lake City: Utah Department of Transportation. Salt Lake City, Ogden, Provo & Vicinity (Wasatch Front) inset. § D5. Archived from the original on December 27, 2013. Retrieved December 26, 2013.
^Utah Department of Natural Resources. Historic Union Pacific Rail Trail (Map). Scale not given. Salt Lake City: Utah Department of Natural Resources. Archived from the original on December 27, 2013. Retrieved December 26, 2013.
^Utah Department of Transportation (2005). "Summit County" (Map). General Highway Map. 1:22,440. Salt Lake City: Utah Department of Transportation. p. 2. Retrieved December 26, 2013.
^Utah Department of Transportation (2005). "Summit County" (Map). General Highway Map. 1:22,440. Salt Lake City: Utah Department of Transportation. p. 3. Retrieved December 26, 2013.
^ abUtah Department of Transportation (November 2008). "Route 80". Highway Resolutions. Utah Department of Transportation. Archived from the original on October 22, 2013. Retrieved December 25, 2013.
^"Rebuilt I-80 Section, Redwood to I-15, Opens on Schedule". The Salt Lake Tribune. October 2, 1990. p. B7. OCLC8086936. ProQuest288431114.
^Jonsson, Dave (May 16, 1991). "Roads Need $4.3 Billion in Next 20 Years". The Salt Lake Tribune. p. C1. OCLC8086936. ProQuest288455107.
^Baltezore, Jay (March 21, 1996). "UDOT Says I-15 Can Be Redone by 2001 UDOT: I-15 Can Be Redone by 2001". The Salt Lake Tribune. p. D1. OCLC8086936. ProQuest288710632.
^"Most Interstate 15 Freeway Ramps Around 2100 South Are Open". The Salt Lake Tribune. November 2, 2000. p. B2. ProQuest281200869.
^Utah Department of Transportation (February 8, 2010). Route 80. Highway Reference (Report). Utah Department of Transportation. Archived from the original(PDF) on September 22, 2008. Retrieved December 25, 2013.
^Utah Department of Transportation (December 17, 2012). Route 15. Highway Reference (Report). Utah Department of Transportation. Archived from the original(PDF) on October 22, 2013. Retrieved December 25, 2013.