Interstate 15 in Utah

Interstate 15 (I-15) runs north–south in the U.S. state of Utah through the southwestern and central portions of the state, passing through many of the population centers of the state, including St. George, Provo, Salt Lake City, and Ogden, the latter three being part of the urban area known as the Wasatch Front. It is the primary north–south highway in Utah, as the vast majority of the state's population lives along its corridor. The only Metropolitan Statistical Area in Utah not connected by I-15 is the Logan Utah-Idaho Metropolitan Statistical Area. In 1998, the Utah Legislature designated the entire length within Utah as the Veterans Memorial Highway.

Interstate 15
Veterans Memorial Highway
I-15 highlighted in red
Route information
Defined by Utah Code §72-4-107
Maintained by UDOT
Length	400.592 mi[1] (644.690 km)
Existed	1956–present
Major junctions
South end	I-15 at Arizona state line
	I-70 near Cove Fort US-50 near Holden and Scipio US-6 in Santaquin and Spanish Fork US-89 in Lehi, Draper, Bountiful, and Farmington I-215 in Murray and North Salt Lake I-80 in South Salt Lake and Salt Lake City I-84 in Riverdale and Tremonton US-91 in Brigham City
North end	I-15 at Idaho state line
Location
Counties	Washington, Iron, Beaver, Millard, Juab, Utah, Salt Lake, Davis, Weber, Box Elder
Highway system
Interstate Highway System Main Auxiliary Suffixed Business Future State highways in Utah Interstate U.S. State Minor Scenic ← SR-14 → SR-16

Route description

The interstate passes through the fast-growing Dixie region, which includes St. George, Cedar City, and eventually most of the major cities and suburbs along the Wasatch Front, including Provo, Orem, Sandy, West Jordan, Salt Lake City, Layton, and Ogden. Around Cove Fort, Interstate 70 begins its journey eastward across the country. The interstate merges with I-80 for about 3 miles (4.8 km) from South Salt Lake to just west of Downtown Salt Lake City and merges with Interstate 84 from Ogden to Tremonton. Along nearly its entire length through the state, I-15 winds its way along the western edge of a nearly continuous range of mountains (including the Wasatch Range in the northern half of the state). The only exceptions are when it passes through the mountains south of Cedar City and again north of Cove Fort.

Southern Utah

I-15 near New Harmony, south of Cedar City, looking north

From Las Vegas, Nevada, I-15 winds and slightly inclines through the Virgin River Gorge in northwest Arizona, then it crosses the border into Utah and Washington County. Just past the border there is a port of entry on each side of the freeway. These ports of entry (weigh stations) are jointly operated by the states of Utah and Arizona and are the first northbound exit and last southbound exit on I-15 in Utah. Heading north-northeast it continues with two lanes in each direction until it reaches an interchange with Southern Parkway (SR-7), which provides access to the St. George Regional Airport. After SR-7, the route turns north as it passes the Bloomington area of the City of St. George and an interchange at Brigham Road where an auxiliary lane is added before it crosses the Virgin River. This marks the lowest elevation along I-15 in the state of Utah, 2,560 feet (780 m) above sea level. Immediately north of the Virgin River, and partially spanning the Santa Clara River, is the Dixie Drive interchange. A collector ramp is added between Dixie Drive and the next interchange with Bluff Street (SR-18). I-15 then narrows to two lanes in each direction and turns northeast again where it passes the eastern side of downtown St. George, with an interchange at St. George Boulevard (SR-34). The Bluff Street and St. George Boulevard interchanges are the southern and northern ends of the St. George I-15 Business Loop. From this point north I-15 generally follows the route of the Old US-91 maintaining a two-lane configuration until it reaches the Wasatch Front in the north-central part of the state. (The route of Old US-91, in turn, followed the older Arrowhead Trail highway to Salt Lake City).

After leaving St. George, I-15 continues northeast and passes through the northern part of the city of Washington. An auxiliary lane is added between St. George Boulevard and Green Springs Road with additional interchanges at Washington Parkway and State Street (SR-9). Northeast of Washington I-15 passes through the northwestern side of the town of Leeds, with one-way interchanges on the southwest and northeast ends of town. After passing through the northwestern part of Toquerville, and an interchange with SR-17 (at Anderson Junction), I-15 resumes a more north-northeastern course as it ascends about 1,000 feet (300 m) higher on the Colorado Plateau. Along the way it passes through the areas of Browse and Pintura, with interchanges at both, as well as two more ranch exits further northeast. After its ascent, it passes by the east of side of Ash Creek Reservoir and then by the northwest corner of Zion National Park, with an interchange providing access to the Kolob Canyon area of the park. Next is an interchange that provides access to New Harmony (several miles west) and Kanarraville (several miles to the northeast). This interchange is also at the border of Washington County and Iron County.

Just after entering Iron County, I-15 reaches the southernmost rest areas along its route within the state (with one each, northbound and southbound). After passing about a mile west of Kanarraville it reaches an interchange in Hamilton Fort. The freeway then briefly turns nearly east before turning north again to pass through the west side of Cedar City. The first interchange is at the southern end of SR-130 (Main Street) and the Cedar City I-15 Business Loop. Just north is the 200 South (SR-56) interchange, which provides access to downtown Cedar City as well as the Cedar City Regional Airport. After this interchange, the freeway turns northeast before the final Cedar City interchange with SR-130 (once again). This interchange is also the northern end of the Cedar City I-15 Business Loop, although no longer indicated as such by signage. The freeway then passes by the eastern edge of Enoch, but without an interchange within that city. After an interchange within the area of Summit, I-15 heads east-northeast before passing by the northwest edge of Parowan, with interchanges on the west (200 South/SR-143) and north (Main Street/SR-274) sides of town. After Parowan, the freeway curves back to a northeast course as it passes about a mile west of Paragonah and reaches an interchange on the north side of that city (SR-271). Continuing northeast it reaches the next pair of rest areas before an interchange with SR-20 and then a ranch exit (exit 100) before leaving Iron County.

Central Utah

An 80 mph speed limit sign in one of the test zones

As I-15 enters Beaver County the interstate turns northwest and winds its way through the mountain pass before heading north again to pass along the western edge of the city of Beaver. Both the southern and northern interchanges in Beaver include the I-15 Business Loop and SR-160—the city streets are South Main Street on the south and 1400 North on the north. Off the 1400 North interchange there is an official rest stop courtesy of Utah Department of Transportation (UDOT) and the local Texaco Station. The freeway then heads slightly west until it passes by the west side of the community of Manderfield and curving back to a north-northeast course. After several miles there is an interchange with Manderfield Road before I-15 winds through another mountain pass and reaches the Sulphurdale interchange. This mountain pass, with summit located at milepost 124.8, is the highest point along I-15 in Utah, at 6,611 feet (2,015 m) above sea level. After passing west of the ghost town of Sulphurdale it reaches the interchange with the western end of I-70. This interchange is on the border of Beaver and Millard counties.

Extinct volcano cone near Fillmore, Utah off I-15

North of the I-15/I-70 interchange, I-70 heads east to Richfield and then toward Denver, Colorado, while I-15 continues north to pass by Cove Fort on the east and reach the Cove Fort (SR-161/Black Rock Road) interchange. Off the Black Rock Road interchange there is an official rest stop courtesy of UDOT and the local Chevron Station. Continuing on, I-15 meanders to the north-northeast before straightening out to the northeast southwest of Kanosh. The freeway passes by the northwest side of Meadow, having an interchange with North Main Street (SR-133). It then passes through the western side of Fillmore. SR-99 follows the length of the I-15 Business Loop through Fillmore, connecting at 850 South on the southwest part of town and North Main Street/Cedar Mountain Road on the northern city limits. Off the North Main Street interchange there is an official rest stop courtesy of UDOT and the local Chevron Station. Continuing north-northwest it has an interchange with 5400 North/Maple Hollow Road (SR-64) before passing by the southeast edge of Holden. Several miles northeast of Holden, US-50 merges with I-15 as it continues northeast and eventually heading through a low mountain pass just after another ranch exit. The US-50 overlap then ends as I-15 passes through the northwest corner of Scipio. Off the Scipio interchange is an official rest stop courtesy of UDOT and Flying J. (US-50 eastbound serves as a connector to I-70 for southbound I-15 motorists.)

View of Mount Nebo from I-15 slightly south of Nephi

Several miles north of Scipio, I-15 leaves Millard County and enters Juab County before turning northeast once again. After an interchange with the Yuba Lake Road is another interchange at Mills Junction/SR-78 just southeast of Chicken Creek Reservoir. The freeway then continues roughly north-northeast until it turns northeast to pass through the southern part of Nephi and an interchange with South Main Street (SR-28). The freeway then turns north to pass through the eastern side of Nephi, with an interchange with 100 North (SR-132). It then curves to the north-northwest before reach the interchange with the northern end of SR-28 about a mile north of town. The interstate then turns north and passes by the eastern side of Mona and has an interchange with SR-52 (300 North). Continuing north it passes by the eastern edge of Rocky Ridge before promptly leaving Juab County and entering Utah County.

Salt Lake area

As the freeway enters Utah County, it also enters Utah Valley, the Wasatch Front, and the Provo-Orem metropolitan area. Turning northeast, it enters the town of Santaquin, where US-6 begins its overlap with I-15 at the interchange with East Main Street/US-6/SR-198. Exiting Santaquin, the interstate turns north to pass by the western edge of Spring Lake before entering Payson, turning north east, and reaching the 800 South (SR-178) interchange. Continuing northeast, the freeway reaches the interchange with North Main Street (SR-115/3200 West) in north Payson. Maintaining its course to the northeast it passes the eastern edge of Benjamin, with an interchange with SR-168 (8000 South), and enters Spanish Fork and gains one lane in each direction. On the north side of Spanish Fork is an interchange with North Main Street (US-6 and SR-156), after which I-15 turns north and gains one more lane in each direction. This interchange also marks the northern end of the overlap with US-6. (The section between Spanish Fork and Lehi was rebuilt in 2010-12 as part of the I-15 CORE project.)

View north along I-15 at the southern junction with I-80 and SR-201 in Salt Lake County

Continuing north with four lanes, it gains an additional Express Lane in both directions. It then passes through the far west side of Springville, with interchanges at 400 South (SR-77) and 1400 North (SR-75). Off the 1400 North interchange is an official rest stop courtesy of UDOT and Flying J. Curving northwest it passes the eastern edge of the Provo Bay of Utah Lake before reaching Provo. Upon entering Provo, it intersects with South University Avenue (the southern terminus of US-189) and East Lakeview Parkway. The interstate then continues northwest, bisecting the west side of Provo, with an interchange with Center Street (SR-114) before leaving Provo and entering Orem. After an interchange with West University Parkway (SR-265), immediately southwest of Utah Valley University, the freeway heads north along the western side of Orem. After interchanges with Center Street, and then 800 North (SR-52) the interstate curves northwest and immediately reaches the interchange with SR-241 (1600 North/600 South). This interchange on the border of Orem and Lindon.

Continuing northwest I-15 passes through the western side of Lindon before passing by the southwest edge of Pleasant Grove, with an interchange at Pleasant Grove Boulevard. Next the freeway enters American Fork with interchanges with at 500 East (SR-180) on the south end of town and West Main Street/Pioneer Crossing (SR-145) on the west end of town. After American Fork, the freeway enters Lehi with it first interchange at East Main Street (SR-73). At this point the interstate narrows to three lanes (plus an Express Lane) in each direction. The next interchange in Lehi is with 2100 North/1200 West (US-89/SR-85). This also begins the first of two I-15/US-89 overlaps. The final interchange in Lehi with Timpanogos Highway/Clubhouse Drive (SR-92), after which the interstate gains an additional 2 lanes, which is just east of Thanksgiving Point. Past Lehi, the interstate exits the Provo metropolitan area and Utah County to enter the Salt Lake City metropolitan area as it passes through the Point of the Mountain.

I-15 in Salt Lake City

As the route enters the Salt Lake Valley from only one of three other points connecting Salt Lake County and Utah County (the others being SR-68 and Traverse Ridge Road), it turns northeast to pass by the eastern edge of Bluffdale. It then enters Draper and heads north to pass through the western part of that city, with four interchanges along the way. The first is with Highland Drive/14600 South (SR-140). The next interchange is with Bangerter Highway (SR-154). The third interchange in Draper is with 12300 South (US-89/SR-71). This interchange is also where US-89 ends its first overlap with the interstate and where I-15 curves slightly to the west. The final interchange in town is on the northern city limits at 11400 South (SR-175). This interchange is on the southern border of Sandy, and is the first of three within that city. The next interchange is with 10600 South (SR-151). The final interchange in Sandy is with 9000 South (SR-209).

Shortly after the last interchange in Sandy it leaves that city and enters Midvale, with the only interchange in that city being with 7200 South (SR-48). After leaving Midvale, I-15 enters Murray and immediately reaches the junction with I-215, a beltway running through many of Salt Lake City's suburbs. Past this interchange, there are two more interchanges in Murray. The first is at 5400 South (SR-173) and the second is with 4500 South/Taylorsville Expressway (SR-266). After this interchange the freeway leaves Murray and passes through the western end of Millcreek (an unincorporated suburb of Salt Lake City) before entering South Salt Lake. After an interchange with 3300 South (SR-171) the interstate reaches the Spaghetti Bowl, which is an interchange with I-80 and SR-201 (21st South Freeway). The southern overlap of I-80 begins at this point as well as the collector roads. The collectors, but not the main I-15 travel lanes, have interchanges with 2100 South and 1300 South, as well as West Temple Street (SR-270) for northbound traffic only. (The West Temple Street off ramps are signed as 900 South.) The Spaghetti Bowl is also where the freeway leaves South Salt Lake enters Salt Lake City.

After entering Salt Lake City, the interstate jogs to the west for the next three interchanges. The first is with SR-269 and includes the off ramps from northbound I-15/I-80 to eastbound 600 South and the on ramps from westbound 500 South to southbound I-15/I-80. The next two interchanges are overlain and include I-80 (the northern end of the I-80 overlap) and 400 South (West University Boulevard). (The later interchange only permits HOV or toll use of the northbound off ramp and the southbound on ramp from and to the respective Express Lanes of I-15/I-80.) North of the ramps with I-80, I-15 loses one lane, leaving three lanes, plus the Express Lane, in both directions. the next interchange is with 600 North (SR-268), following which the freeway jogs to the west for the next two interchanges. After the 900 West interchange (which does not include a northbound off ramp) is the Warm Springs Road (northbound) and 2300 North (southbound) interchange. The freeway then returns to is northern course, but before leaving Salt Lake City and Salt Lake County, it has northbound on and off ramps for the Beck Street (US-89) interchange.

Ogden area

Northbound along I-15/84 in Ogden

After entering Davis County, the city of North Salt Lake, and the Ogden-Clearfield metropolitan area, I-15 has the southbound on and off ramps for the Beck Street (US-89) interchange. Next is the junction between I-15 and I-215 (Belt Route), which only provides a southbound off ramp from I-15 to I-215 and a northbound on ramp from I-215 to I-15. Just after this another partial interchange that only includes a southbound off ramp to West Center Street. The freeway then heads northwest to the 2600 South (SR-93) interchange, which is centered on the border of North Salt Lake and Woods Cross. Continuing north once again, the interstate reaches its next interchange, which is with 500 South (SR-68). Parts of this interchange are spread over three cities, with Woods Cross on the south, a panhandle of Bountiful in the middle, and West Bountiful on the north. Continuing north it comes to another partial interchange with 400 North, which only includes a northbound off ramp and a southbound on ramp. After a slight jog to the east comes the junction with US-89 (500 West). This junction straddles the north–south border between West Bountiful and Bountiful. It is also a partial interchange in that it has only a southbound off ramp and a northbound on ramp. It also is the beginning of the second 1-15/US-89 overlap.

Continuing north it leaves West Bountiful and enters Centerville before reaching the Parish Lane (400 North/SR-105) interchange. About a mile north, I-15 begins a stretch where the Legacy Parkway (SR-67) parallels the interstate on the west, with little more than train tracks in between. About another mile north the freeway leaves Centerville and enters Farmington. Next comes the partial interchange with 200 West (SR-227), which only includes a northbound off ramp and a southbound on ramp. Heading north-northeast it reaches the I-15/Legacy Highway/US-89/Park Lane (SR-225) interchange. This sprawling interchange provides a northbound off ramp and southbound on ramp for US-89, a southbound off ramp and a northbound on ramp for Legacy Parkway, as well connection with Park Lane. The interchange is just west of the Lagoon amusement park and is the end of the second I-15/US-89 overlap. From this interchange it heads northwest before leaving Farmington and entering Kaysville.

Just inside Kaysville are two former rest areas. While the ramps and parking areas are still intact, there are no signage or facilities remaining. Further on is the Kaysville (200 North/SR-273) interchange. Continuing northwest I-15 leaves Kaysville and enters Layton, along with its three interchanges. The first interchange is with Layton Parkway and just north of it the Express Lanes end, leaving just three lanes in each direction. The next two interchanges are with Hill Field Road (SR-232) and then Antelope Drive (2000 North/SR-108). After leaving Layton the interstate enters Clearfield and reaches the 700 South SR-193 interchange. From this interchange north I-15 runs along the western edge of Hill Air Force Base. The next interchange is with 650 North, which also provides direct access to the west part of the air force base. Just after this interchange the freeway leaves Clearfield, turns north, and enters Sunset, but has no further interchanges before leaving that city and Davis County.

Just prior to the next interchange I-15 enters Weber County and the city of Roy. After curving slightly to the east the freeway reaches the 5600 South (Utah State Route 97) interchange, which provides access to the north end of the air force base, including the Hill Aerospace Museum that located immediately north of the base. The next interchange is with Riverdale Road (SR-26). As a partial interchange, there is only a northbound off ramp to east bound SR-26 and a southbound on ramp from westbound SR-26. (Eastbound SR-26 provides the only access to eastbound I-84.) At this interchange the interstate also transitions from Roy to Riverdale. Heading northwest, I-15 then merges with I-84, but there is no northbound access to I-84, nor westbound access from I-84 to I-15. This also begins the I-15/I-84 overlap. Immediately northwest of this interchange is the Ogden-Hinckley Airport, however since the airport is on a hill slightly above, it is not visible from the freeway. Two additional lanes are added north of this junction for a total of four in each direction. Just after leaving Riverdale, the interstate enters Ogden and reaches the 31st Street (3100 South/SR-79) interchange. Curving back to the northwest, the freeway comes to the 24th South (SR-53) interchange. Although the signage specifies "24th Street", this partial interchange (which only provides a northbound off ramp and a southbound on ramp) is actually with Pennsylvania Avenue (also SR-53) which promptly connects with 24th Street (2400 South) northeast of the interchange.

As it leaves Ogden and enters West Haven, I-15 curves to the north-northwest before coming to the 21st Street (2100 South/SR-104) interchange. The freeway then leaves West Haven and enters Marriott-Slaterville and immediately crosses the Weber River. The next interchange is with 12th Street (1200 South/SR-39), at which point the freeway loses one lane in each direction. Continuing on with three lanes in each direction the interstate reaches the 400 North interchange. Similar to the 24th Street interchange, although signage indicates "400 North", this interchanges actually connects with Pioneer Road, which promptly connects with 400 North just east of the interchange. North of this interchange, I-15 heads directly north to leave Marriott-Slaterville and enter Farr West. Continuing north it reaches the 2700 North (SR-134) before it curves to the north-northwest and leaves Farr West and Weber County. At the 2700 North interchange, the freeway narrows to two lanes in each direction and remains so for the remainder of its route in Utah.

Box Elder County

I-15 warning sign for potentially drowsy drivers

Upon entering the final county (Box Elder) along its route in Utah, I-15 also enters the area of South Willard and then reaches the Willard (2000 West/SR-126) interchange. (SR-126 connects with US-89 just west of the interchange.) Before leaving the South Willard area and entering the city of Willard, I-15 begins about a two-mile stretch that runs along the western shore of the Willard Bay of the Great Salt Lake. Its next interchange is with 750 North SR-315. Straddling the northern border between Willard and Perry are ports of entry for both directions of traffic. Continuing north through Perry it passes a rest area for northbound traffic before it reaches the next interchange, which is with 1100 South (US-91). This interchange straddles the northern border of Perry and the southern border of Brigham City. (US-91 continues northeast to Logan and points northward.) Curving slight to the west, the interstate reaches the Forest Street interchange followed by the 900 North (SR-13) interchange. Immediately north of 900 North the freeway passes immediately to the west of the Brigham City Airport. West of the airport there is also a rest area for southbound traffic. At the north end of the airport, the freeway leaves Brigham City and before continuing on a slight more westerly, northern course.

After about a mile in unincorporated Box Elder County, I-15 enters Honeyville and then reaches the Honeyville/Bear River (6900 North/SR-240) interchange. Continuing northwest the interstate leaves Honeyville and immediately crosses the Bear River. It then enters the town of Elwood and reaches the Tremonton/Garland (5200 West/SR-13) interchange. The freeway then leaves Elwood and enters Tremonton shortly thereafter. Just inside Tremonton, is the I-15/I-84/SR-30 junction. From this junction, I-84 and SR-30 head northwest to Snowville and on to Burley and Boise, Idaho, while I-15 continues north through Tremonton. This interchange is also the northern end of the I-15/I-84 overlap and the southern end of the I-15/SR-30 overlap. Straddling the northern city limits of Tremonton is another interchange signed as "Tremonton/Garland". This second interchange of the same name is with 1000 North. Curving slightly to the east, it passes by the western edge of Garland before coming to the Riverside (15200 North/SR-30) interchange, which is just southwest of that city and is the northern end of the I-15/SR-30 overlap. Continuing a slightly winding course north, the interstate reaches the Plymouth (20800 North/SR-13) interchange, which is just northwest of that town. Heading north, and then to the north east the freeway reaches the Portage (25800 North/Center Street), which is the last interchange in the state and is just east of that town. About a mile north of the last interchange is the Utah-Idaho border, where I-15 leaves the Ogden-Clearfield metropolitan area. From there I-15 continues north to Malad City and on to Pocatello.[2]

History

The southwest–north alignment followed by I-15 was a major transportation corridor in the early 20th century, followed by auto trails such as the Arrowhead Trail (south from Salt Lake City), Evergreen National Highway (entire length), and Banff-Grand Canyon Road (north from Nephi). In 1926, when the numbered system of U.S. highways was created, this route was signed U.S. Route 91[3]

The route of I-15 from St. George to Brigham City was built along the corridor of what was U.S. Route 91 from 1926 to 1974.[3] In 1974 I-15 was reasonably intact and US-91 was deleted, with the unfinished segments signed as Temporary I-15. The route north of Brigham City was built along the corridor of an old routing of U.S. Route 191. This highway was also deleted once I-15 was reasonably intact. However, a different route in Utah was re-designated US-191 in 1982. Also, by the time it completed the section, UDOT recalibrated the mileposts and renumbered the exits, reducing the overall distance by approximately three miles.[4]

In 1975, UDOT would construct a wildlife crossing located near the town of Beaver. The Utah Division of Wildlife Resources considers this to be the first wildlife overpass built in the United States.[5]

Prior to 1977 the route of I-15 (and US-91 before) was also designated State Route 1 by the state of Utah, but no portion of the route was signed with this number.

The last section of I-15 within the state of Utah (as well as the entire length of the route) was finally completed in November 1990,[6] only to have major reconstruction projects commence (starting in Salt Lake County) about 7 years later. The entire length of I-15 within Utah was designated by the Utah Legislature in 1998 as the Veterans Memorial Highway.[7]

In 2004, UDOT finally renumbered the mile markers along I-15 north of Nephi. (When I-15 was originally built, there were several large gaps along the route, including south of Nephi. In addition, the original plans for I-15 were to run along the west side of Nephi, instead of the final alignment along the east side of the city. Mileage along the unconstructed sections was estimated. After the entire length of the freeway was completed, there was a discrepancy of an extra three miles along all sections north of Nephi. UDOT had been aware of the problem for many years, but delayed corrective action for the issue.) The following year, in 2005, UDOT renumbered the exits to correspond to the corrected mile markers. The result was exit numbers north of Nephi were reduced by three.[8]

In January 2009, the speed limit on two sections of I-15 together totaling 34 miles (55 km) was raised to 80 miles per hour (130 km/h) as a "test," making Utah the second state to currently have speed limits greater than 75 miles per hour (121 km/h). In September 2013, with a few brief exceptions, the speed limit north of Leeds (other than the Wasatch Front, between Santaquin and Brigham City) was raised to 80 miles per hour (130 km/h).[9]

In 2015, the UDOT raised the speed limit on the Wasatch Front urban stretch through Salt Lake City to 70 miles per hour (110 km/h). Also, in 2016, the speed limit through the St. George metro area was raised to 70 miles per hour (110 km/h).

As of October 2016, the longest continuous high-occupancy-vehicle (HOV) facility in the U.S. is on I-15 in Utah, extending approximately 72.0 mi (115.9 km) from Spanish Fork to Layton with a single HOV lane each direction for a total of 144.0 mi (231.7 km) of HOV lanes.[10]

Reconstruction projects

I-15 corridor reconstruction project

Taking place from between April 1997 and July 2001, the Interstate 15 reconstruction project was the Utah Department of Transportation's first major Interstate reconstruction project. The project involved the renovation of 16.2 miles (26.1 km) of Interstate 15 from 600 North in Salt Lake City to 10600 South (SR-151) in Sandy. Improvements included repaving concrete, adding another general-purpose lane and a high-occupancy-vehicle (HOV) lane, along with an auxiliary lane between major interchanges in each direction through the Salt Lake City metropolitan area. Approximately 130 bridges were either constructed or reconstructed, including the conversion of 7 diamond interchanges into single point urban interchanges, and the reconstruction of three major junctions with other Interstate and state routes, including I-80, SR-201, and I-215. In addition, a traffic management system was added to the entire length of the Interstate in the Salt Lake County region. This reconstruction cost US$1.63 billion, with $448 million being federally funded and $1,184 million being funded by Utah.[11]

EXPRESSLink project

The I-15 EXPRESSLink project took place between December 2008 and Fall 2010. It involved the renovation of I-15 between 500 North in Salt Lake City and the northern terminus of I-215 in North Salt Lake. Renovations included new concrete and added a high-occupancy-vehicle (HOV) lane in both directions. In order to accommodate the new width of the freeway, bridges at Beck Street, U.S. 89, and 1100 North were replaced. The bridges at 800 and 1100 North were replaced by one bridge at 1100 North.[12]

11400 South interchange addition

A new single point interchange was constructed between 2008 and November 2010 at 11400 South in Draper. The project also widened I-15 from 10600 South to just past 11400 South from 3 to 4 general purpose lanes, extended the high-occupancy-vehicle (HOV) lane that previously ended at 10600 South, and added an auxiliary lane between the two interchanges.[13]

I-15 CORE project

The I-15 Corridor Expansion (CORE) project was a design-build project that reconstructed 24 miles (39 km) of I-15 in Utah County, Utah between Lehi Main Street to 8000 South Spanish Fork. The $1.725 billion project was the fastest billion-dollar public highway project ever completed in the United States.[14] The project was completed on December 15, 2012–35 months from the original notice to proceed—and finished $260 million under budget (coming in at $1.465 billion total).[15] I-15 CORE widened the freeway by two lanes in each direction and replaced the original asphalt with new 40-year concrete pavement; rebuilt 63 bridges; reconstructed 10 freeway interchanges; and extended the high-occupancy-vehicle (HOV) lanes from Orem to Spanish Fork.[16] (Prior to I-15 CORE, HOV lanes had already been installed from Lehi to Orem.)

South Davis improvements

The South Davis Improvements project, which took place between April 2014 and August 2015, constructed new high-occupancy-vehicle (HOV) lanes between the I-215 interchange in North Salt Lake and the US-89 interchange in Farmington; replaced I-15 bridges at 2600 South, 1500 South, 500 South (SR-68) and 400 North (SR-106); reconfigured the interchange at 2600 South into a partial and 500 South into a full diverging diamond interchange; and added active transportation improvements, with better pedestrian and bicycle facilities at 500 South, 400 North and Parrish Lane. The entire project costed US$126 million.[17]

The Point Project

The two-year Point Project widened I-15 from 4 to 6 lanes in each direction between 12300 South in Draper and SR-92 in Lehi, a distance of approximately seven miles. The project also replaced the existing pavement with new 40-year concrete, reconstructed the 14600 South (SR-140) interchange as a single-point urban interchange to improve traffic flow, and installed new traffic management technology such as cameras, ramp meters, electronic message signs, and fiber optics. The project costed US$215 million. With the completion of The Point project, nearly all of I-15 along the Wasatch Front has been reconstructed within the past two decades. One last section in Lehi, from S.R. 92 to Main Street (SR-73) remains, and is programmed to begin construction in Spring 2018.[18]

I-15 Technology Corridor

The Utah Department of Transportation will reconstruct the I-15 Technology Corridor between Lehi Main Street and S.R. 92 (Timpanogos Highway) starting in 2018. The Tech Corridor is the last section of I-15 in Utah County to be reconstructed in recent years. The actual construction elements to be included will be based on the results of the ongoing engineering, traffic and cost analysis. Those elements are expected to include I-15 reconstructed and widened with two new lanes in each direction from Lehi Main Street to S.R. 92, One-way frontage road system from 2100 North to S.R. 92, interchange reconstruction at S.R. 92 and 2100 North, 13 bridge replacements, a new Triumph Boulevard bridge over I-15, and bike and pedestrian improvements. The initial budget for this project is $450 million.[19]

Future elements not being constructed at this time are expected to include a new North Lehi interchange, a one-way frontage road system extended from S.R. 92 to the new North Lehi interchange, and freeway-to-freeway connector ramps at 2100 North to connect I-15 to the future Mountain View Corridor freeway.

To ease traffic, UDOT will add an extra lane in each direction.[20]

I-15 Express Lanes

In January 2019, UDOT announced that plans were underway to add another lane to accommodate an HOV Lane for growing population and traffic in northern Davis county and southern Weber county from Layton Parkway to I-84 in Ogden. In addition to this, there were multiple side projects in the works along the 11-mile corridor, including bridge widening and deck replacements at several places and Ramp Meters at on-ramps at Riverdale Road in Riverdale, 650 North and 700 South both in Clearfield. Construction started in May 2019 and is set to be done by June 2020.[21]

The I-15 Southbound Project

As the name would imply, The I-15 Southbound Project is designed exclusively for I-15 Southbound to add another lane from the Spaghetti Bowl, specifically, at Utah S.R. 201 in Salt Lake City and South Salt Lake, to 12300 South in Draper. In addition to this, the I-15 Interchange at I-215 in Midvale would also be fixed, with another plan to expand 7200 South to three lanes from I-15 to Bingham Blvd in both directions. Also, the Union Pacific Rail Road Bridge (USRR) is planned to be fixed with the road.

The I-15 portion of this project started in Spring of 2018. The new lane from 7800 South to 12300 South portion was completed in December 2018. I-15 portion is anticipated to be completed by the end of 2019.

Meanwhile, the 7200 South portion started at the start of 2019 and is planned to continue into 2020 under pending Union Pacific Railroad Negotiations.[22]

Exit list

In 2005, all exits north of Nephi were renumbered to eliminate a milepost equation. The original surveyed route for I-15 in the 1960s passed Nephi to the west, however by the time the route was actually constructed in the 1980s the plans were changed to pass Nephi on the east, resulting in a discrepancy in the exit numbers north of Nephi from actual mileage.[23]

County	Location	mi[1]	km	Old exit[24]	New exit	Destinations	Notes
Washington	​	0.000	0.000	Arizona–Utah state line I-15 south (Veterans Memorial Highway) continues into Arizona
	St. George	0.462	0.744	1	[lower-alpha 1]	Ports of Entry
		2.135	3.436		2	SR-7 east (Southern Parkway)
		4.641	7.469		4	Brigham Road
		5.619	9.043	[lower-alpha 2]	5	Dixie Drive
		6.309	10.153		6	I-15 Bus. north / SR-18 north (Bluff Street)
		8.652	13.924		8	I-15 Bus. south / SR-34 west (St. George Boulevard)
	Washington	10.910	17.558		10	Green Springs Drive	Former SR-212
		13.386	21.543		13	Washington Parkway
	Washington–Hurricane line	15.888	25.569		16	SR-9 east (State Street)
	Leeds	22.579	36.337		22	SR-228 north (Main Street)	Northbound exit and southbound entrance
		23.703	38.146		23	SR-228 (Silver Reef Road)	Southbound exit and northbound entrance
	Toquerville	27.470	44.209		27	SR-17 south – Toquerville, Hurricane
	​	30.682	49.378		30	Browse
	​	31.861	51.275		31	Pintura
	​	33.435	53.808		33	Snowfield
	​	36.763	59.164		36	Black Ridge
	​	40.253	64.781		40	Kolob Canyons
	​	42.159	67.848		42	New Harmony, Kanarraville	Former SR-58 (north-northwest) & former SR-144 (west)
Iron	​	44.132	71.024	[lower-alpha 2]	[lower-alpha 1]	Rest Areas	Northbound and southbound rest areas
	​	51.149	82.316		51	Hamilton Fort, Kanarraville	Former SR-58 (south)
	Cedar City	56.787	91.390		57	I-15 Bus. north / SR-130 (South Main Street) to SR-14 east
		58.837	94.689		59	SR-56 (200 North)
		62.497	100.579		62	I-15 Bus. south (North Main Street) / SR-130 to SR-14 east
	​	70.263	113.077		71	Summit, Enoch	Former SR-38
	Parowan	75.183	120.995		75	I-15 Bus. north / SR-143
		77.801	125.209		78	I-15 Bus. south / SR-274 (Main Street) to SR-143 / SR-271 – Parowan, Paragonah
	​	82.253	132.373		82	SR-271 south (Main Street) – Paragonah
	​	87.418	140.686			Rest Areas	Northbound and southbound rest areas
	​	94.453	152.007		95	SR-20 to US-89 – Panguitch, Circleville, Kanab
	​	99.690	160.436		100	Freemont Road	Marked on signage as "Fremont Wash"; signed as "Ranch Exit" until January 2018[25]
Beaver	Beaver	108.745	175.008		109	I-15 Bus. / SR-160 north to SR-21 / SR-153 – Beaver, Milford
		111.780	179.892		112	I-15 Bus. / SR-160 south to SR-21 / SR-153 – Beaver, Milford, Manderfield
	​	120.126	193.324		120	Manderfield
	​	125.009	201.182	125	[lower-alpha 3]	Ranch Exit	Interchange closed and removed in 2003
	​	129.438	208.310		129	Sulphurdale
Millard	​	132.170	212.707		132	I-70 east – Richfield, Denver	Western end of I-70
	​	134.875	217.060		135	SR-161 south (Historic Cove Fort)
	​	138.073	222.207		138	Dog Valley	Signed as "Ranch Exit" until July 2018[26]
	​	146.493	235.758		146	Kanosh	Former SR-133
	Meadow	158.265	254.703		158	SR-133 south – Kanosh
	Fillmore	163.370	262.919		163	I-15 Bus. / SR-99 north to SR-100 west – Fillmore
		166.723	268.315		167	I-15 Bus. / SR-99 south to SR-100 west – Fillmore
	​	173.507	279.232		174	SR-64 to US-50 – Delta, Holden
	​	178.330	286.994		178	US-50 west – Delta, Holden	South end of US-50 overlap
	​	183.638	295.537		184	Tower Road	Signed as "Ranch Exit" until 2017[27]
	Scipio	188.439	303.263		188	US-50 east – Scipio	North end of US-50 overlap
Juab	​	202.189	325.392		202	Yuba State Park
	​	206.553	332.415		207	SR-78 east – Mills
	Nephi	222.812	358.581		222	I-15 Bus. north / SR-28 (South Main Street)
		225.248	362.502		225	SR-132 (100 North)
	​	228.065	367.035		228	I-15 Bus. / SR-28 south – Nephi	Former SR-41
	​	233.161	375.236	236	233	SR-54 – Mona
Utah	Santaquin	242.447	390.181	245	242	South Santaquin
		244.788	393.948	248	244	US-6 west (East Main Street)	South end of US-6 overlap
	Payson	248.829	400.451	252	248	SR-178 east (800 South)
		250.923	403.821	254	250	SR-115 (Main Street)
	​	253.557	408.060	256	253	SR-164 (8000 South) – Spanish Fork, Benjamin
	Spanish Fork	257.246	413.997	260	257A	SR-156 south (Main Street)
		257.666	414.673	[lower-alpha 2]	257B	US-6 east – Price	North end of US-6 overlap
		257.636	414.625	261	258	US-6 east	Exit reconfigured as exit 257B; was southbound exit and northbound entrance
	Springville	259.963	418.370	263	260	SR-77 (400 South)
		261.781	421.296	265	261	SR-75 east (1400 North)
	Provo	263.358	423.834	266	263	US-189 north (University Avenue)
		265.364	427.062	268	265	SR-114 (Center Street)
	Orem	269.072	433.029	272	269	SR-265 (University Parkway)
		270.660	435.585	274	271	Center Street
		271.670	437.210	275	272	SR-52 (800 North) to US-189
	Orem–Lindon line	272.767	438.976	276	273	SR-241 (1600 North)
	Pleasant Grove	275.279	443.019	278	275	SR-135 (Pleasant Grove Boulevard)
	American Fork	276.436	444.881	279	276	SR-180 north (500 East)
		278.493	448.191	281	278	SR-145 (Main Street)
	Lehi	279.701	450.135	282	279	SR-73 (Main Street)
		282.311	454.336	285	282	US-89 south (2100 North) to SR-85 west	South end of US-89 overlap; US-89 signed southbound only
				[lower-alpha 2]	283	Triumph Boulevard	Southbound exit only
		283.985	457.030	287	284	SR-92 (Timpanogos Highway) – Highland, Alpine
Salt Lake	Draper	288.272	463.929	291	288	SR-140 west (14600 South)
		289.832	466.439	293	289	SR-154 (Bangerter Highway)
		291.358	468.895	294	291	US-89 north / SR-71 (12300 South)	North end of US-89 overlap
				295	[lower-alpha 3]	US-89 north (State Street) – Sandy	Closed; former north end of US-89 overlap
	Draper–Sandy– South Jordan tripoint	292.612	470.913	[lower-alpha 2]	292	SR-175 (11400 South)
	Sandy–South Jordan line	293.634	472.558	297	293	SR-151 (10600 South)
		295.616	475.748	298	295	SR-209 (9000 South)
	Midvale	297.920	479.456	301	297	SR-48 (7200 South)
	Murray	299.005	481.202	302	298	I-215 (Belt Route)	Signed southbound as exit 298A (east) and 298B (west)
		300.300	483.286	303	300	SR-173 (5300 South)
		301.653	485.463	304	301	SR-266 (4500 South)
	South Salt Lake	303.414	488.298	306	303	SR-171 (3300 South)
		304.691	490.353	307	304	I-80 east – Cheyenne	South end of I-80 overlap; I-80 west exit 123B; part of the "Spaghetti Bowl" interchange
		305.231	491.222	308A	305A	SR-201 west (2100 South Freeway) / 900 West – West Valley	Exit formerly unsigned southbound; part of the "Spaghetti Bowl" interchange
		305.198	491.169	308B	305B	2100 South (SR-201)	Formerly signed as exit 308 southbound
	Salt Lake City	306.315	492.966	309A	305C	1300 South	Formerly signed as exit 309 southbound
		306.607	493.436	309B	305D	900 South (SR-270)	Northbound exit and southbound entrance
		307.500	494.873	310	306	600 South (SR-269)	Northbound exit and southbound entrance
		307.740	495.260		307	400 South	HOV/toll access only; northbound exit and southbound entrance
						400 South	Southbound exit and northbound entrance
		308.079	495.805	311	308	I-80 west – Salt Lake City International Airport, Reno	North end of I-80 overlap, I-80 east exit 120
		309.333	497.823	312	309	SR-268 east (600 North)
		310.239	499.281	313	310	1000 North	No northbound exit
		311.792	501.781	314	311	2300 North
Salt Lake–Davis county line	Salt Lake City–North Salt Lake line	313.128	503.931	315	312	US-89 south (Beck Street)
Davis	North Salt Lake	313.275	504.167	316	313	I-215 south (Belt Route) – Salt Lake City International Airport	Southbound exit and northbound entrance
		314.301	505.818	317	314	Center Street	Southbound exit only
	North Salt Lake–Woods Cross line	315.243	507.334	318	315	SR-93 (2600 South)
	Woods Cross–Bountiful– West Bountiful tripoint	316.870	509.953	320	316	SR-68 (500 South)
	West Bountiful	317.557	511.058	321	317	SR-106 east (400 North)	Northbound exit and southbound entrance
	West Bountiful–Bountiful line	318.024	511.810			US-89 south (500 West)	South end of US-89 overlap; southbound left exit and northbound entrance
	Centerville	319.512	514.205	322	319	SR-105 (Parrish Lane)
	Farmington	322.916	519.683	325	322	SR-227 north (200 West)	Northbound exit and southbound entrance
		324.026	521.469	326	324	US-89 north to I-84 east – South Ogden	North end of US-89 overlap; northbound exit and southbound entrance
		324.243	521.819	[lower-alpha 2]	324	Legacy Parkway	Southbound exit and northbound entrance
		324.741	522.620	327	325	SR-225 (Park Lane)	Northbound access is via exit 324
	Kaysville	328.640	528.895	331	328	SR-273 (200 North)
	Layton			332	330	I-15 Bus. (Main Street) / SR-126 north	Exit closed upon completion of Layton Parkway interchange (same exit number, but further north); I-15 Bus. decommissioned in Layton upon move; was northbound exit and southbound entrance
		330.019	531.114	[lower-alpha 2]	330	SR-126 north (Layton Parkway)
		331.589	533.641	334	331	SR-232 (Hill Field Road)
		332.883	535.723	335	332	SR-108 (Antelope Drive)
	Clearfield	334.066	537.627	336	334	SR-193 (700 South)
		335.800	540.418	338	335	SR-103 (650 North)
Weber	Roy	338.447	544.678	341	338	SR-97 (5600 South)
	Riverdale	339.133	545.782	342	339	SR-26 (Riverdale Road) to I-84 east	Northbound exit and southbound entrance
		340.227	547.542	343	340	I-84 east – Cheyenne	South end of I-84 overlap; northbound access via exit 339
	Ogden	341.948	550.312	344	341	SR-79 (31st Street)
		343.067	552.113	345	342	SR-53 (24th Street)	Northbound exit and southbound entrance
	West Haven	343.852	553.376	346	343	SR-104 (21st Street)
	Marriott-Slaterville	344.968	555.172	347	344	SR-39 (12th Street)
		346.726	558.001	349	346	400 North
	Farr West	349.361	562.242	352	349	SR-134 (2700 North)
Box Elder	​	351.853	566.253	354	351	SR-126 (2000 West) to US-89 – Willard, Pleasant View
	Willard	357.554	575.427	360	357	SR-315 (750 North)
		358.566	577.056	361	[lower-alpha 1]	Ports of Entry
	Perry	360.542	580.236	363	[lower-alpha 1]	Rest Area	Northbound rest area only
	Brigham City	362.020	582.615	364	362	US-91 (1100 South) to US-89
		363.738	585.380	366	363	Forest Street
		365.508	588.228	368	365	SR-13 (900 North Street)
	​	366.558	589.918		[lower-alpha 1]	Rest Area	Southbound rest area only
	Honeyville	372.734	599.857	375	372	SR-240 to SR-13 – Honeyville, Bear River
	Tremonton	376.532	605.970	379	376	I-15 Bus. / SR-13 – Garland, Bear River
		379.334	610.479	382	379	I-84 west – Boise	North end of I-84 overlap; I-84 east exit 41
		381.037	613.220	383	381	I-15 Bus. south – Garland
	​	385.266	620.026	387	385	SR-30 east – Riverside, Logan
	​	392.387	631.486	394	392	SR-13 south – Plymouth
	​	398.817	641.834	402	398	Portage	Former SR-90
	​	400.592	644.690	Idaho–Utah state line I-15 north continues into Idaho
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Closed/former       Concurrency terminus       HOV only       Incomplete access

Notes

1. Ports of entry and rest areas were previously assigned exit numbers; however, that practice has been discontinued.
2. The new exits numbered 5 (Dixie Drive), 257B (US-6), 292 (11400 South), and 324 (Legacy Parkway), as well as the new rest areas around mile marker 44, were built after the renumbering project was complete and, therefore, do not have "old" exit numbers
3. Exit was closed before the renumbering scheme took place.

References

1. Staff (December 17, 2012). "Highway Reference" (PDF). Utah Department of Transportation. Retrieved May 21, 2013.
2. Google (June 30, 2013). "Overview Map of Interstate 15 in Utah" (Map). Google Maps. Google. Retrieved June 30, 2013.
3. Auto Road Atlas (Map). Rand McNally. 1926.
4. Stober, Dan. "Interstate 15". Utah Highways. Self-published. Archived from the original on March 9, 2007. Retrieved August 8, 2007.
5. "Wildlife Crossing Structures". Utah Wildlife Migration Initiative. Retrieved November 22, 2020.
6. "Interstate 15". aaroads.com. AAROads. August 4, 2016. Retrieved June 5, 2016.
7. Utah State Legislature. "Section 72-4-201". Utah Code. State of Utah. Archived from the original on July 11, 2008. Retrieved June 29, 2013.
8. Decker, Marin (July 12, 2005). "I-15 exit sign changes toss a curve at motorists: Utah County milepost errors being corrected". Deseret News. Salt Lake City: Deseret Digital Media. Retrieved June 5, 2018.
9. Davidson, Lee (September 17, 2013). "Utah Adds 289 Miles of Roads with 80 MPH Speed Limits". The Salt Lake Tribune. Retrieved October 14, 2013.
10. "UDOT and UHP launch Express Lane education and enforcement blitz – Transportation Blog". blog.udot.utah.gov. Retrieved December 31, 2017.
11. "FHWA - Center for Innovative Finance Support - Project Profiles". www.fhwa.dot.gov. Retrieved December 31, 2017.
12. "I-15 project in North Salt Lake enters final phase | KSL.com". Retrieved December 31, 2017.
13. "New I-15 exit now open at 11400 South". DeseretNews.com. September 22, 2010. Retrieved December 31, 2017.
14. "Utah DOT Project Comes in $260 Million Below Budget, Fastest Billion Dollar Highway Project in U.S." AASHTO Journal. American Association of State Highway and Transportation Officials. December 21, 2012. Archived from the original on January 15, 2016. Retrieved May 11, 2013.
15. "Officials Celebrate the Completion of I-15 CORE". Salt Lake City: KSTU-TV. December 15, 2012. Archived from the original on December 26, 2013. Retrieved May 11, 2013.
16. Lee, Jasen (November 3, 2012). "Open Road Ahead: All I-15 Lanes in Utah County to Open Monday". Deseret News. Salt Lake City. Retrieved May 11, 2013.
17. "Revamped I-15 corridor in Davis County ready for traffic | KSL.com". Retrieved December 31, 2017.
18. "The Point Project Now Complete – Transportation Blog". blog.udot.utah.gov. Retrieved December 31, 2017.
19. Herald, Karissa Neely Daily. "UDOT approves I-15 funding along Lehi Technology Corridor". Daily Herald. Retrieved December 31, 2017.
20. "Prepare yourself for a massive, 3-year road construction project in Utah County". fox13now.com. April 25, 2018. Retrieved April 25, 2018.
21. "Project Summary". www.udot.utah.gov. Retrieved August 21, 2019.
22. "The I-15 Southbound Project". www.udot.utah.gov. Retrieved August 21, 2019.
23. Decker, Marin (July 10, 2005). "I-15 exit sign changes toss a curve at motorists". Deseret News. Retrieved November 23, 2018.
24. Staff. "Milepost Project". Utah Department of Transportation. Archived from the original on June 8, 2007.
25. "I-15 - Google Maps". Google Maps. December 2018. Retrieved July 30, 2019.
26. "I-15 - Google Maps". Google Maps. May 2019. Retrieved July 30, 2019.
27. "I-15 - Google Maps". Google Maps. April 2018. Retrieved July 30, 2019.

External links

• Media related to Interstate 15 in Utah at Wikimedia Commons