Interstate 15: Difference between revisions

Major cities; Bolded cities are officially-designated control cities for signs
	San Diego, California; Riverside, California; San Bernardino, California; Los Angeles, California (via Interstate 10); Barstow, California (California only, Nevada uses Los Angeles as the control city south of Las Vegas); Baker, California (As seen on signs between Barstow and Baker); Las Vegas, Nevada; St. George, Utah; Provo, Utah; Salt Lake City, Utah; Ogden, Utah; Pocatello, Idaho; Idaho Falls, Idaho; Butte, Montana; Helena, Montana; Great Falls, Montana; Shelby, Montana; Lethbridge, Alberta;

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Revision as of 21:10, 10 August 2007

Template:Infobox Interstate

Interstate 15 (abbreviated I-15) is the fourth-longest north-south transcontinental interstate highway in the United States, traveling through the states of California, Nevada, Arizona, Utah, Idaho, and Montana.

In California, this freeway is a major transportation corridor linking the San Diego-Tijuana metropolitan area with the Riverside-San Bernardino-Ontario Metropolitan area, and various suburban communities between them.

It is also the main artery of transportation through the entire state of Utah connecting the Wasatch Front and Dixie urban areas. It also serves as the primary access route from Southern California to Las Vegas, Nevada, a major travel/tourist destination throughout the year.

More recently, I-15 has begun to serve as a heavily traveled commuter route between the Mojave Desert communities of Victorville, Barstow, Hesperia, Apple Valley, and Adelanto in California, due to rapid population growth and associated residential, commercial, and industrial development.

There are a total of 400 exits along the entire I-15.

Most of Interstate 15 in California (San Bernardino County) and Nevada are undergoing major improvements and will be completed by 2009.^[1]

The I-15 corridor between Los Angeles and Las Vegas has long been proposed as a maglev train route; in 2004 the California-Nevada Interstate Maglev project held public meetings on the plan.^[2] Additionally the I-15 corridor along the Wasatch Front was approved and finalized in 2006 by a sales-tax increase referendum to be the route of a double-decker commuter train called FrontRunner; construction began in 2005.

Route description

Lengths
	mi	km
CA	287	462
NV	124	200
AZ	29	47
UT	401	645
ID	196	315
MT	396	647
Total	1,433	2,307

This highway's southern terminus is in San Diego, California at the Interstate 8 merge, 18 miles (29 km) north of the international border with Mexico. However, work is being done to extend this to Interstate 5. The current work on this extension is signed California State Highway 15. At current time (July 2006), there is a continuous freeway between I-8 and I-5, but various intersections and acceleration/deceleration lanes are not up to interstate standards. The northern terminus is in Sweetgrass, Montana at the international border between the United States and Canada, where it becomes Alberta provincial highway 4.

California

North of its junction with the Riverside Freeway, State Route 91, in the Inland Empire near Corona, the route follows (roughly) the old U.S. Highway 91 and U.S. Highway 395. North of Devore, the highway follows the approximate alignment of historic U.S. Highway 66 along with U.S. 91 and 395. U.S. 395 breaks away at Hesperia and the route continues the approximate route of co-signed 91 and 66 until about the Mojave River, 35 miles (56 km) to the north. At that point, I-15 follows the old route of U.S. 91 exclusively. For many parts of the highway, high-voltage power lines, like Path 46 and Path 27, almost all from Hoover Dam, follow the freeway, many of them link distant power stations to the Los Angeles metro area.

Interestingly, the starting point of Interstate 15 was originally planned to be in San Bernardino at an interchange with the San Bernardino Freeway, Interstate 10 (I-10). This was logical as I-15 was following the old alignment of the historic route U.S. Route 66 which passed through San Bernardino. The segment was completed accordingly. However, legislation was later passed to extend the interstate to San Diego. But instead of extending the existing freeway from the I-10 interchange south, the California Department of Transportation created a new segment in Devore that 'branched' off of the original alignment and bypassed San Bernardino altogether. This segment's alignment is generally northeast to southwest for about 15 miles (24 km). Then, in Fontana/Rancho Cucamonga, its directional alignment shifts to north-south where it eventually junctions with Interstate 10 (about 15 miles west of the original interchange in San Bernardino). The segment that had been built from Devore to San Bernardino was retained as an interstate, but was re-numbered as Interstate 215. Note that during the construction of I-15's present alignment, and for some time afterwards, I-215 was numbered as I-15E.

Nevada

Interstate 15 begins in Primm, continues through Las Vegas along the Las Vegas Strip corridor. Then the interstate crosses the border with Arizona in Mesquite. The whole interstate in Nevada runs entirely in Clark County.

Arizona

I-15 just clips the northwestern corner of Arizona with a total length of 29.4 miles (47 km).^[3] The stretch is separated from the rest of the state and has one major exit, at Beaver Dam/Littlefield, Arizona. It includes a spectacular section where the road twists between the narrow walls of the Virgin River Gorge.

Utah

I-15 continues through Utah for just over 400 miles (640 km). It is the main north-south connection for the state. The highway approximately follows the old alignment of U.S. Highway 91 from St. George to Brigham City. The highway 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 (5 km) from South Salt Lake to just west of Downtown Salt Lake City and also 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 (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.

Extinct volcano cone near Fillmore, Utah off I-15.

Idaho

I-15 passes through Idaho for nearly 200 miles (320 km). The highway runs through Pocatello, Blackfoot, and Idaho Falls. It also merges with Interstate 86.

Montana

Interstate 15 continues onward through nearly 400 miles (640 km) of Montana through the cities of Butte, Helena and Great Falls, intersecting with Interstate 90, Interstate 115 and Interstate 315. At Sweetgrass, I-15 terminates upon crossing the international border into Alberta, Canada; however, I-15 signage is present on Alberta Highway 4 southbound from Lethbridge to the U.S.-Canada Border.

History

Interstate 15 was constructed along the route of U.S. Route 91. Once Interstate 15 was relatively intact U.S. 91 was decommissioned, except for one part in Northern Utah/Southern Idaho where Interstate 15 instead followed the route of former U.S. Route 191.

Interstate 15 had an eastern branch bypassing San Bernardino, California, and a western branch in Idaho. I-215 around San Bernardino was I-15E^[4], and the western I-86 was once called I-15W.^[5]

Future

Template:Future road Redesignation of SR 15 in San Diego as I-15 will eventually occur when the freeway's interchange with SR 94 is updated to Interstate standards. The interchange currently has left-exits and blind merges, and is due to be updated with a long-awaited widening of SR 94 in 2008. At that time SR 15 will be resigned as part of I-15. The remaining portion of SR 15 conforms with Interstate standards.