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 most of the state's population centers, including St. George and those comprising the Wasatch Front: Provo–Orem, Salt Lake City, and Ogden–Clearfield. It is Utah's primary north–south highway, as the vast majority of the state's population lives along its corridor; the Logan metropolitan area is the state's only Metropolitan Statistical Area through which I-15 does not pass. In 1998, the Utah State Legislature designated Utah's entire  portion of the road as the Veterans Memorial Highway. Route description. The Interstate passes through the fast-growing Dixie region, which includes St. George and 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, I-70 begins its journey eastward across the country. The Interstate merges with I-80 for about from South Salt Lake to just west of Downtown Salt Lake City and merges with I-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. 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, 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 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. 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 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. 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.) 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 reaching 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. Northern Utah. 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 northeast, 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-164 (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 2010–2012 as part of the I-15 CORE project.) 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 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 its 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 is with Timpanogos Highway / Clubhouse Drive (SR-92), after which the Interstate gains an additional two 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. 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 offramps 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 offramps from northbound I-15/I-80 to eastbound 600 South and the onramps 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 offramp and the southbound onramp 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 offramp) 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 offramps for the Beck Street (US 89) interchange. Ogden area. After entering Davis County, the city of North Salt Lake, and the Ogden–Clearfield metropolitan area, I-15 has the southbound on- and offramps for the Beck Street (US 89) interchange. Next is the junction between I-15 and I-215 (Belt Route), which only provides a southbound offramp from I-15 to I-215 and a northbound onramp from I-215 to I-15. Just  after this is another partial interchange that only includes a southbound offramp 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  offramp and a southbound onramp. 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 offramp and a northbound onramp. 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 offramp and a southbound onramp. Heading north-northeast, it reaches the I-15 / Legacy Highway / US 89 / Park Lane (SR-225) interchange. This sprawling interchange provides a northbound offramp and southbound onramp for US 89, a southbound offramp and a northbound onramp 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 airforce 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 (SR-97) interchange, which provides access to the north end of the airforce base, including the Hill Aerospace Museum that is located immediately north of the base. The next interchange is with Riverdale Road (SR-26). As a partial interchange, there is only a northbound offramp to east bound SR-26 and a southbound onramp 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 offramp and a southbound onramp ) 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. 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 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 northeast, 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. 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 US 91. The route of I-15 from St. George to Brigham City was built along the corridor of what was US 91 from 1926 to 1974. 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 US 191. This highway was also deleted once I-15  was reasonably intact. However, a different route in Utah was redesignated 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 . 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. Prior to 1977 the route of I-15 (and US 91 before) was also designated SR-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, 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. 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 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. In January 2009, the speed limit  on two sections of I-15 together totaling was raised to as a "test", making Utah the second state to currently have speed limits greater than . 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 . In 2015, the UDOT raised the speed limit on the Wasatch Front urban stretch through Salt Lake City to . Also, in 2016, the speed limit through the St. George metro area was raised to . As of October 2016, the longest continuous high-occupancy-vehicle (HOV) facility in the  U.S. is on I-15 in Utah, extending approximately from Spanish Fork to Layton with a single HOV lane each direction for a total of of HOV lanes. Reconstruction projects. I-15 corridor reconstruction project. Taking place from between April 1997 and July 2001, the I-15 reconstruction project was the Utah Department of Transportation's first major Interstate reconstruction project. The project involved the renovation of of I-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 seven 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 $1.63 billion, with $448 million being federally funded and $1,184 million being funded by Utah. 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, US 89, and 1100 North were replaced. The bridges at 800 North and 1100 North were replaced by one bridge at 1100 North. 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 three to four 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. I-15 CORE project. The I-15 Corridor Expansion (CORE) project was a design–build project that reconstructed 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. 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). 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. (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 $126 million. The Point Project. The two-year Point Project widened I-15 from four to six lanes in each direction between 12300 South in  Draper and SR-92 in Lehi, a distance of approximately . 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 $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 SR-92 to Main Street (SR-73) remained and was widened spring 2018 . I-15 Technology Corridor. The Utah Department of Transportation reconstructed the I-15 Technology Corridor between Lehi Main Street and SR-92 (Timpanogos Highway) starting in 2018. The Tech Corridor was the last section of I-15 in Utah County to be reconstructed in recent years. The actual construction elements included was based on the results of the ongoing engineering, traffic, and cost analysis. Those elements include I-15 reconstructed and widened with two new lanes in each direction from Lehi Main Street to SR-92, one-way frontage road system from 2100 North to SR-92, interchange reconstruction at SR-92 and 2100 North, 13 bridge replacements , a new Triumph Boulevard bridge over I-15, and bike and pedestrian improvements. The final cost for the project was $415 million. 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 SR-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. 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 corridor, including bridge widening and deck replacements at several places and Ramp Meters at onramps 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. The I-15 Southbound Project. The I-15 Southbound Project is designed exclusively for I-15 Southbound to add another lane from the Spaghetti Bowl, specifically, at Utah SR-201 in Salt Lake City  and South Salt Lake, to 12300 South in Draper. In addition, the I-15/I-215 interchange in Midvale would also be modified, with another plan to expand 7200 South to three lanes from I-15 to Bingham Blvd in both directions. The Union Pacific Rail Road Bridge (USRR) is planned to be improved along 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. 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 to the east, resulting in a discrepancy in the exit numbers north of Nephi from actual mileage.