Interstate 280 (I-280) is a major north–south auxiliary Interstate Highway in the San Francisco Bay Area of Northern California. It runs from I-680 and US Route 101 (US 101) in San Jose to King and 5th streets in San Francisco, running just to the west of the larger cities of San Francisco Peninsula for most of its route.
From I-880 in San Jose to State Route 1 (SR 1) in Daly City, I-280 was built and dedicated as the Junipero Serra Freeway, after the Spanish Franciscan friar who founded the first nine of 21 Spanish missions in California from San Diego to San Francisco. One of the dedication signs (in Daly City) still indicates that the Junipero Serra Freeway is known as the "World's Most Beautiful Freeway" due to its scenic route through the San Francisco Peninsula. From SR 1 to the James Lick Freeway (US 101) in San Francisco it is officially called the John F. Foran Freeway (after a former member of the California State Legislature). From the James Lick Freeway to its northern end at King and 5th streets, I-280 is called the Southern-Embarcadero Freeway.
==Route description== <!--Route descriptions should be written in a present-day perspective. Any changes or significant events may be indicated in the History section.-->
The entirety of I-280 is defined in section 580 of the California Streets and Highways Code as Route 280, and that the highway is from "Route 101 in San Jose to Route 80 in San Francisco via Daly City". Route 280 was never fully constructed to I-80, its parent Interstate, as defined. The constructed northernmost segment of I-280 from 6th to 5th streets in San Francisco is also not considered an Interstate Highway according to the Federal Highway Administration (FHWA)'s route logs, In between San Jose and San Francisco, I-280 passes through Santa Clara, Cupertino, Los Altos, and Los Altos Hills before it settles along its scenic route just to the west of the cities of the San Francisco Peninsula in San Mateo County and just to the east of the Santa Cruz Mountains. I-280 reemerges in a decidedly urbanized area in the city of San Bruno, passing through South San Francisco and Daly City before it runs across a southeastern swath of the city of San Francisco on the way to its northern terminus.
The segment of the Junipero Serra Freeway between Cupertino (SR 85) and Daly City (SR 1) has been called the "World's Most Beautiful Freeway" since its dedication in the 1960s. Drivers along this portion of I-280 are treated to scenic views of the Santa Cruz Mountains to the west and, at a few points, San Francisco Bay to the east and are isolated by hills from the cities to the east. Through much of this segment, the freeway is actually running just inside the eastern rim of the rift valley of the San Andreas Fault. A particularly attractive stretch of the freeway from Hillsborough to Belmont provides a view at Crystal Springs Reservoir, formed by water piped over from Hetch Hetchy Valley in Yosemite National Park, partly filling the rift valley. The waters are impounded by Crystal Springs Dam, which drains into San Francisco Bay via San Mateo Creek; I-280 crosses the deep valley formed by this creek on the Doran Memorial Bridge, completed in 1969.
<gallery mode=packed heights=180px widths=240px caption="I-280">
File:Joseph P. Sinclair Fwy I-280 at US-101.jpg|Aerial view of I-280 in San Jose, looking northeast toward the Joe Colla Interchange (I-680/US 101) in the distance
File:Interstate 280 near Stanford p1130161.jpg|I-280 near Stanford University
Image:Scenic-portion-of-280.jpg|Scenic portion of I-280
File:CA Route 92 aerial San Mateo to Half Moon Bay.jpg|Aerial view directed west showing interchange with SR 92; Crystal Springs Reservoir runs north-south parallel to I-280 through the middle of the photograph
</gallery>
For nearly all of its length, I-280 runs roughly parallel and several miles to the west of US 101 (Bayshore Freeway). Both freeways are north–south routes connecting San Jose with San Francisco; however, unlike I-280, the route that US 101 takes between the two cities goes entirely through urbanized areas. The vast majority of the population of the San Francisco Peninsula lives somewhere between I-280 and US 101.
Although it was originally intended to do so, I-280 does not intersect with I-80, its parent Interstate. The northern terminus of I-280 is within about of I-80's western terminus (at the interchange with US 101), but the two Interstates do not directly connect; instead, I-280 complies with numbering conventions by virtue of its interchanges with the southern ends of I-680 and I-880, both of which connect to I-80 at their northern terminuses. Although San Francisco planned and has had several opportunities to connect I-280 to I-80, it has chosen to use the money for other purposes. Instead, I-280's northernmost extension, which includes a significant double-deck section (with northbound traffic on the lower deck and southbound traffic on the upper), primarily functions now as a spur into the Financial District, San Francisco, as suggested by signage on northbound US 101 at the Alemany Maze.
Major intersections include US 101 and SR 1 in San Francisco, I-380 in San Bruno, SR 92 in San Mateo, SR 85 in Cupertino, and I-880 and I-680 and US 101 in San Jose.
I-280 is part of the California Freeway and Expressway System and 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 (FHWA). I-280 is eligible for the State Scenic Highway System and, from the San Mateo–Santa Clara county line to the San Bruno city limits, is officially designated as a scenic highway by the California Department of Transportation (Caltrans), meaning that it is a substantial section of highway passing through a "memorable landscape" with no "visual intrusions", where the potential designation has gained popular favor with the community. The Junipero Serra Freeway is the name of I-280 from SR 1 in San Francisco to SR 17, as named by Assembly Concurrent Resolution 140, Chapter 208 in 1967, in honor of Spanish missionary Junípero Serra, who founded many of California's missions in the 18th century. I-280 from its southern terminus at US 101 and I-680 north to I-880 in San Jose is part of the Sinclair Freeway (named after Joseph P. Sinclair, District Engineer for District 4 California Division of Highways). A high faux-sandstone statue of Serra was placed at the Crystal Springs Rest Area in 1975. Visible in both directions from the highway, it was removed by Caltrans in 2025. According to an official statement, "The installation did not meet current Transportation Art Program requirements and had been a frequent target of graffiti and vandalism."
The SLAC National Accelerator Laboratory, a research center operated by Stanford University, houses a 2-mile-long linear accelerator that extends underground, running 30 feet below I-280 near the Sand Hill Road exit in Menlo Park.
History
thumb|left|upright=0.9|1955 map of the planned Interstates in the [[San Francisco Bay Area. These early plans essentially called for an Interstate loop route that would head south down the San Francisco Peninsula from San Francisco to San Jose, then head north through the eastern cities of the East Bay to Vallejo. This route now basically comprises present-day I-280, I-680, and I-780.]]
<!--forget this section for now — I can't figure out the LR between SR 92 and Crystal Springs Road
Legislative Route 237 was defined in 1956, running along Junipero Serra Boulevard from John Daly Boulevard (State Route 1 – pre-1964 Legislative Route 56) in Daly City south to San Bruno. A 1959 extension took it south to Crystal Springs Road in San Bruno. The route from State Route 92 near San Bruno to
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I-280 was added to the Interstate Highway System on September 15, 1955, as a route from San Jose north to San Francisco. This ran along the present alignment of I-280 south of San Francisco, but, in San Francisco, it was instead intended to run north parallel to SR 1, past the planned west end of I-80 which would have been at the junction with the Panhandle Freeway just south of Fulton and Park Presidio, along what would have been the Park Presidio Freeway north to the south approach to the Golden Gate Bridge. At that point, I-280 would have met I-480 (Embarcadero Freeway), which would have headed east on Doyle Drive (US 101), the Golden Gate Freeway, and onto the Embarcadero Freeway to reach the San Francisco–Oakland Bay Bridge. I-480 would have continued south on the never-built section of the Southern-Embarcadero Freeway from Folsom and the Embarcadero to 5th and King streets, then along the present Southern-Embarcadero Freeway to meet the Southern Freeway (now I-280) near the Alemany Maze, which served as the US 101 Bypass until I-280 was built. The I-280 number was approved on November 10, 1958.
For the scenic portion, the section of I-280 between SR 85 (Cupertino) and SR 84 (Woodside) was completed in the late 1960s alongside SR 85. The section between SR 92 (San Mateo) and SR 84 was not completed until the 1970s. Until then, traffic was routed on Cañada Road between the two ends.
thumb|Aerial photo of the [[Stanford Linear Accelerator Center, showing the 2-mile building housing the accelerator beamline, which passes under I-280.]]
thumb|right|alt=Cars driving near Page Mill Road on I-280.|Cars driving near Page Mill Road on I-280
A direct freeway connection between I-280 and I-80 was never completed. I-280 was planned to run along The Embarcadero underneath the Bay Bridge approach/I-80 to connect to SR 480 and then loop back to the Bay Bridge approach/I-80 near 1st Street. After the 1989 Loma Prieta earthquake, plans to connect I-280 to I-80 were abandoned, the earthquake-damaged Embarcadero Freeway was torn down in 1991, and the north end of I-280 was reconfigured to the present-day King Street on/offramps in 1997. It has been suggested this stunt nudged the state of California to find the funds to complete the freeway. The ramps opened five years later in 1981. In 2010, a resolution was introduced in the state legislature to name it the Joe Colla Interchange in memory of the late councilmember.
In 2021 University of California, Davis, researchers published a report on wildlife-vehicle collisions based on California Highway Patrol and insurance data over the past five years, according to which five of the 20 stretches of highway in the state with the highest costs for this reason are on I-280, the worst being between San Bruno and Cupertino.
Exit list
See also
References
External links
- AARoads – Interstate 280
- Planning maps for the pre-1968 planned route of the freeway along Junipero Serra Boulevard in San Francisco
- California Highways: I-280
- Freeways not built in S.F.