Interstate 8
Interstate 8 is an Interstate Highway in the southwestern United States. It runs from the southern edge of Mission Bay at Sunset Cliffs Boulevard in San Diego, California, almost at the Pacific Ocean, to the junction with I-10, just southeast of Casa Grande, Arizona. In California, the freeway travels through the San Diego metropolitan area as the Ocean Beach Freeway and the Mission Valley Freeway before traversing the Cuyamaca Mountains and providing access through the Imperial Valley, including the city of El Centro. Crossing the Colorado River into Arizona, I-8 continues through the city of Yuma across the Sonoran Desert to Casa Grande, in between the cities of Phoenix and Tucson.
The first route over the Cuyamaca Mountains was dedicated in 1912, and a plank road served as the first road across the Imperial Valley to Yuma; east of there, the Gila Trail continued east to Gila Bend. These were later replaced by U.S. Route 80 across California and part of Arizona, and Arizona State Route 84 between Gila Bend and Casa Grande. The US 80 freeway through San Diego was largely complete by the time it was renumbered as I-8 in the 1964 state highway renumbering; east of San Diego, the US 80 roadway was slowly replaced by I-8 as construction progressed in the Imperial Valley. The Arizona portion of the road was built starting in the 1960s. Several controversies erupted during the construction process; questionable labor practices in Imperial County led to the federal conviction of mobster Jimmy Fratianno, and a U.S. House of Representatives subcommittee found that the Arizona government had mismanaged financial resources.
The route was completed in 1975 through California, and by 1977 through Arizona, though the bridge over the Colorado River was not completed until 1978. Since then, the freeway through San Diego has been widened due to increasing congestion, and another portion in Imperial County had to be rebuilt following damage by the remnants of Hurricane Kathleen.
Route description
I-8 is part of the National Highway System, a network of highways that are considered essential to the country's economy, defense, and mobility by the Federal Highway Administration. The freeway from the eastern junction with California State Route 98 to the eastern end is designated as part of the Juan Bautista de Anza National Historic Trail auto tour route, promoted by the National Park Service.San Diego to Arizona border
The entirety of Interstate 8 in California is defined in section 308 of the California Streets and Highways Code as Route 8:The section of Route 8 defined in subdivision is not considered an Interstate Highway according to the Federal Highway Administration 's route logs, but is still signed as an Interstate by Caltrans.
The freeway begins at the intersection of Sunset Cliffs Boulevard and Nimitz Boulevard in San Diego. For its first few miles, it parallels the San Diego River floodway. Near Old Town San Diego, I-8 intersects with I-5 as well as with Rosecrans Street, the former routing of SR 209.
As the freeway enters Mission Valley, it continues eastward, bisecting the area known as "Hotel Circle" that has several hotels. I-8 then has interchanges with SR 163, I-805, and I-15. In La Mesa, the route intersects SR 125, and in El Cajon it intersects with SR 67. From Mission Valley through El Cajon, it is paralleled by the San Diego Trolley Green Line.
East of El Cajon, it ascends into the mountains and the Cleveland National Forest, traveling through towns such as Alpine then going by the Viejas Casino before reaching Pine Valley. This route achieves four 4,000-foot high points at Carpenter Summit, then crosses the Pine Valley Creek Bridge before the Laguna Summit, followed by the Crestwood Summit, then the Tecate Divide, After the Laguna Summit, the road passes a U.S. border patrol interior checkpoint that was constructed in 1995 near Buckman Springs Road turnoff just east of the summit. However, this resulted in smugglers driving the wrong way on I-8 at high speeds in order to avoid the checkpoint, causing several crashes, even after concrete barriers were installed. The freeway intersects with SR 79 in the national forest before passing through the La Posta and Campo Indian reservations.
In Boulevard, I-8 has an interchange with the eastern end of SR 94.
I-8 straddles the San Diego–Imperial county line for a few miles before turning east. At the Mountain Springs/In-Ko-Pah grade, the freeway is routed down two separate canyons—Devils Canyon for westbound traffic and In-Ko-Pah Gorge for eastbound traffic—as it descends in. In places, the median is over wide. This portion of the road is known for high winds through the canyons that have made driving difficult, sometimes resulting in closure of the freeway; in 1966, the California Highway Patrol estimated that winds blew at speeds of up to. The route enters the Imperial Valley, where it intersects with SR 98, a highway leading to Calexico, and passes near the Desert View Tower. I-8 then goes through Ocotillo and Coyote Wells before entering the city of El Centro several miles later.
In El Centro, I-8 intersects with SR 86 and SR 111, both north–south routes which connect to I-10 in the Coachella Valley, north of the Salton Sea. SR 115 and SR 98 end at I-8 east of El Centro. The route also has the lowest above-ground elevation of any Interstate at below sea level near El Centro. The freeway then traverses the Imperial Sand Dunes Recreation Area and intersects with SR 186 leading south to Baja California Norte, Mexico. I-8 runs parallel to the All-American Canal across the desert for roughly. At points in eastern Imperial County, the Mexican border is less than south of the Interstate. I-8 then passes through Felicity and Winterhaven before crossing the Colorado River on a bridge into Yuma, Arizona.
I-8 is part of the California Freeway and Expressway System and is eligible for the State Scenic Highway System from I-5 to the western junction of SR 98, though it is not an official state scenic highway. It is officially known as the Border Friendship Route from San Diego to the Arizona state line. The Interstate is signed as the Ocean Beach Freeway west of I-5. For the entire length within San Diego County and into Imperial County, it is signed as the Kumeyaay Highway, after the local Native American tribe and their traditional trade route which the Interstate follows. Between Old Town and El Cajon, I-8 is called the Mission Valley Freeway. In 2014, I-8 had an annual average daily traffic of 11,800 vehicles between Bonds Corner Road and SR 115, as well as between SR 98 and Imperial Highway, and 239,000 vehicles between I-805 and I-15, the latter of which was the highest AADT for the highway in California.
Yuma to Casa Grande
I-8 enters Arizona from California at the Colorado River bridge at Yuma. It initially heads south through Yuma until the interchange with US 95, where the freeway begins to turn to the east and passes through eastern Yuma and Fortuna Foothills, briefly paralleling US 95 and passing through a second border inspection station. In the Gila Mountains, the eastbound lanes of I-8 cross under the westbound freeway, briefly traveling to the left near Telegraph Pass before reverting. The Telegraph Pass is a highway pass about east of Yuma in the northwest Sonoran Desert.West of Wellton, the highway takes a northeasterly course, paralleling the Gila River and passing to the south of Roll. Through this part of Arizona, I-8 passes along the northern edge of the Barry M. Goldwater Air Force Range and to the south of the Yuma Proving Ground. It keeps a northeastern heading, passing through the community of Dateland, until it reaches Gila Bend. There, the freeway intersects SR 85 heading north to Phoenix and south to the Organ Pipe Cactus National Monument.
After leaving Gila Bend, I-8 takes a southeastern course as it passes through the Sonoran Desert National Monument. Exiting the national monument grounds, the highway continues on an easterly bearing to a junction with SR 84, a highway that parallels I-8 to the north and goes through Casa Grande, while I-8 passes to the south of both Stanfield and Casa Grande. I-8 reaches its eastern terminus southeast of Casa Grande Mountain Park at an interchange with I-10, which continues north to Phoenix, and south to Tucson.
The combination of SR 85 between I-10 and I-8 as well as I-8 between SR 85 and I-10 in Casa Grande has been promoted as a bypass of the Phoenix area for long-distance travelers on I-10. In 2014, I-8 had an AADT of 5,200 vehicles between Butterfield Trail and Freeman Road, and 44,400 vehicles between SR 280 and Araby Road east of Yuma, the latter of which was the highest AADT for the highway in Arizona. In the early 2010s, I-8 from Casa Grande to Gila Bend was sometimes used for smuggling both drugs and humans.
History
The I-8 designation was accepted as a chargeable Interstate by the American Association of State Highway Officials in 1957, and was added to the state highway system in 1964 by the California State Legislature; the US 80 designation was removed at that time.San Diego area
The freeway that would become I-8 was constructed in the mid-20th century through the San Diego area. The section west of I-5 was originally part of SR 109, and was added to I-8 in 1972. In later years, the California Department of Transportation made efforts to widen the freeway as congestion increased.Initial construction
Much of Alvarado Canyon Road from San Diego to La Mesa was originally built between 1947 and 1950, a bypass of the old US 80 routing along El Cajon Boulevard and La Mesa Boulevard. Work began to convert the original US 80 divided highway into a freeway in 1960, and the freeway was complete west of El Cajon by April 1962. Priority was given to planning US 80 in 1962 by the California Chamber of Commerce. In 1964, I-8 was officially designated by the California State Legislature, and the US 80 designation was removed. By 1965, I-8 from Fairmount Avenue to El Cajon Boulevard was one of the first freeway stretches in the county to have a center barrier installed in the median.The Ocean Beach Freeway section west of I-5 was authorized as Route 286 in 1959. In 1962, four alternate routes were proposed for this part of the freeway, and for Rosecrans Street. Route 286 was renumbered to SR 109 in the 1964 renumbering. Plans for the Old Town interchange between I-5, I-8, SR 209, and SR 109 date from 1962, although several concerns had to be taken into account, including the preservation of historical Old Town and keeping traffic through the area moving during construction. The goal was to begin the process in 1966, and complete the interchange in 1969. There were concerns about a $3 million shortfall in funding during May 1966, which caused the San Diego Chamber of Commerce Highway Committee to recommend the completion of SR 109 as a project. This was projected to be the final highway project before I-5 was completed in San Diego County.
The building phase started on September 22, 1966, on the interchange that was to replace the intersection of Pacific Highway and Rosecrans Street. The cost of the interchange was projected to be $10.86 million. SR 109 was planned to follow Camino del Rio up to the Frontier traffic circle, where the city of San Diego would resume construction; both SR 109 and SR 209 were to be built in the future. The eight-lane freeway was projected to relieve traffic in the Frontier Street area coming from the San Diego Sports Arena. Bidding for the SR 109 contract was to begin in 1968, after the City Council endorsed the route in December 1967. Completion of both the interchange and SR 109 was planned for early 1969. An interchange was planned at Midway Drive, and the western end of the freeway was to be at Sunset Cliffs and Nimitz boulevards. The cost of the SR 109 project was estimated to be $2.3 million.
The ramp from south I-5 to Camino del Rio opened in February 1968, and a second ramp from southbound I-5 to eastbound I-8 opened in August 1968, with the remainder of the project to be completed in summer 1969. The groundbreaking for the Ocean Beach Freeway took place on September 23, 1968, with the estimated completion to take place within 15 months. However, rain in February 1969 delayed many construction projects across the county, including the SR 109 extension. The entire project was completed in September, with the road scheduled to open in October. The routing of SR 109 was officially added to I-8 in 1972.