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155-653: The design has been well received, and has since become one of the most popular freeway -to- arterial interchange designs in North America. It has also been used occasionally in some European countries, such as Germany , Hungary , Italy , the Netherlands , and the United Kingdom . In Ontario , the specific variation is identified by a letter/number suffix after the name. Ontario's naming conventions are used in this article. The letter A designates that two ramps meet

310-747: A World Series game between two Bay Area baseball teams, the Loma Prieta earthquake struck and caused widespread infrastructural damage, including the failure of the Bay Bridge , a major link between San Francisco and Oakland . Even so, the Bay Area's technology industry continued to expand and growth in Silicon Valley accelerated: the United States census confirmed that year that San Jose had overtaken San Francisco in terms of population. The commercialization of

465-649: A dual highway ) in 1932 between Cologne and Bonn . It then rapidly constructed the first nationwide system of such roads. The first North American freeways (known as parkways) opened in the New York City area in the 1920s. Britain, heavily influenced by the railways, did not build its first motorway , the Preston By-pass ( M6 ), until 1958. Most technologically advanced nations feature an extensive network of freeways or motorways to provide high-capacity urban travel, or high-speed rural travel, or both. Many have

620-466: A median separates the opposite directions of traffic. This strip may be as simple as a grassy area, or may include a crash barrier such as a " Jersey barrier " or an "Ontario Tall Wall" to prevent head-on collisions . On some freeways, the two carriageways are built on different alignments; this may be done to make use of available corridors in a mountainous area or to provide narrower corridors through dense urban areas . Control of access relates to

775-663: A B4 from a diamond . The parclo B4 is less common in Ontario than the parclo A4, with the only examples being the following: There are two such interchanges in Saskatoon, Saskatchewan , along Circle Drive , at College Drive and Attirdge Drive/Preston Avenue N. The following B4 interchanges were changed from full cloverleafs: Some parclo B4 interchanges such as the intersection of Interstate 40 and U.S. Route 401 in Raleigh, North Carolina , have been fitted with signals at each ramp meeting

930-955: A B4 interchange in the mid-1990s with the construction of the Solomon Pond Mall . Also, the West Road interchange on I-75 in Woodhaven, Michigan , was upgraded from a B2 to a B4 in the mid 1980s after suburban sprawl had made the B2 interchange obsolete. In Indiana , the B4 design along IN 37 at its Bloomington interchange with IN 45/46 was retained when the former route was converted to become I-69 's exit 120 in 2018. At least four B4 designs are known to exist in Kentucky : The US 83 interchange on I-80 in North Platte, Nebraska , has also recently been upgraded to

1085-694: A cloverleaf and trumpet interchange when it opened in 1937, and until the Second World War , boasted the longest illuminated stretch of roadway built. A decade later, the first section of Highway 401 was opened, based on earlier designs. It has since gone on to become the busiest highway in the world. The word freeway was first used in February 1930 by Edward M. Bassett . Bassett argued that roads should be classified into three basic types: highways, parkways , and freeways. In Bassett's zoning and property law -based system, abutting property owners have

1240-449: A complex multimodal transportation network. The earliest archaeological evidence of human settlements in the Bay Area dates back to 8000–10,000 BC. The oral tradition of the Ohlone and Miwok people suggests they have been living in the Bay Area for several hundreds if not thousands of years. The Spanish empire claimed the area beginning in the early period of Spanish colonization of

1395-620: A few years earlier, which now provides drinking water for 2.4 million people in the Bay Area. By 1915, the city had been sufficiently rebuilt and advertised itself to the world during the Panama Pacific Exposition that year, although the effects of the quake hastened the loss of the region's dominant status in California to the Los Angeles metropolitan area . During the 1929 stock market crash and subsequent economic depression , not

1550-552: A first in the United States, and four years later a majority of voters in the Bay Area rejected California Proposition 8 , which sought to constitutionally restrict marriage to opposite-sex couples but ultimately passed statewide. The Bay Area was also the center of contentious protests concerning racial and economic inequality . In 2009, an African-American man named Oscar Grant was fatally shot by Bay Area Rapid Transit police officers , precipitating widespread protests across

1705-465: A folded diamond are actually local streets; surface roads upgraded to higher standards often do this to save money on land acquisition. This type of interchange long predates the parclo; the Merritt Parkway and Queen Elizabeth Way , both built in the 1930s, used mainly folded diamonds and cloverleaves . Another example of this is Highway 401 's interchange with Highway 2 east of Tilbury (Exit 63):

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1860-620: A freeway, specialized pedestrian footbridges or tunnels may also be provided. These structures enable pedestrians and cyclists to cross the freeway at that point without a detour to the nearest road crossing. Access to freeways is typically provided only at grade-separated interchanges , though lower-standard right-in/right-out (left-in/left-out in countries that drive on the left) access can be used for direct connections to side roads. In many cases, sophisticated interchanges allow for smooth, uninterrupted transitions between intersecting freeways and busy arterial roads . However, sometimes it

2015-434: A larger number of guide signs than other roads, and the signs themselves are physically larger. Guide signs are often mounted on overpasses or overhead gantries so that drivers can see where each lane goes. Exit numbers are commonly derived from the exit's distance in miles or kilometers from the start of the freeway. In some areas, there are public rest areas or service areas on freeways, as well as emergency phones on

2170-499: A legal status which limits the types of vehicles that can use a highway, as well as a road design that limits the points at which they can access it. Major arterial roads will often have partial access control , meaning that side roads will intersect the main road at grade, instead of using interchanges, but driveways may not connect directly to the main road, and drivers must use intersecting roads to access adjacent land. At arterial junctions with relatively quiet side roads, traffic

2325-722: A major domestic military and naval hub, with large shipyards constructed in Sausalito and across the East Bay to build ships for the war effort. The Army's San Francisco Port of Embarkation was the primary origin for Army forces shipping out to the Pacific Theater of Operations . That command consisted of fourteen installations including Fort Mason, the Oakland Army Base , Camp Stoneman and Fort McDowell in San Francisco Bay and

2480-518: A milepost system but does not use milepost markers. In Europe and some other countries, motorways typically have similar characteristics such as: Two-lane freeways , often undivided, are sometimes built when traffic volumes are low or right-of-way is limited; they may be designed for easy conversion to one side of a four-lane freeway. (For example, most of the Bert T. Combs Mountain Parkway in eastern Kentucky

2635-447: A motorway is understood as a public road with dual carriageways and at least two lanes each way. All entrances and exits are signposted and all interchanges are grade separated. Central barrier or median present throughout the road. No crossing is permitted, while stopping is permitted only in an emergency. Restricted access to motor vehicles, prohibited to pedestrians, animals, pedal cycles, mopeds, agricultural vehicles. The minimum speed

2790-772: A national-level or even international-level (e.g. European E route ) system of route numbering . There are several international standards that give some definitions of words such as motorways, but there is no formal definition of the English language words such as freeway , motorway , and expressway , or of the equivalent words in other languages such as autoroute , Autobahn , autostrada , autocesta, autoput , that are accepted worldwide—in most cases these words are defined by local statute or design standards or regional international treaties. Descriptions that are widely used include: One green or blue symbol (like [REDACTED] ) appears at motorway entry in countries that follow

2945-589: A number of patterns. The actual pattern is determined by a number of factors including local topology, traffic density, land cost, building costs, type of road, etc. In some jurisdictions feeder/distributor lanes are common, especially for cloverleaf interchanges ; in others, such as the United Kingdom, where the roundabout interchange is common, feeder/distributor lanes are seldom seen. Motorways in Europe typically differ between exits and junctions. An exit leads out of

3100-689: A parclo AB interchange includes the Highway 417 and the Woodroffe Avenue interchange in Ottawa . Other variants, not describable using Ontario's system, eliminate one or more outside ramps, while leaving the loop ramps in those quadrants. In the United States, folded diamonds are frequently used in interchanges with roads that have a railroad line closely paralleling the surface street; entrance/exit ramps are not permitted to have level crossings in modern American practice. In California , Caltrans currently has

3255-594: A park and where intersecting streets crossed over bridges. The Southern State Parkway opened in 1927, while the Long Island Motor Parkway was closed in 1937 and replaced by the Northern State Parkway (opened 1931) and the contiguous Grand Central Parkway (opened 1936). In Germany, construction of the Bonn-Cologne Autobahn began in 1929 and was opened in 1932 by Konrad Adenauer , then

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3410-560: A policy that whenever cloverleaf interchanges between freeways and surface streets are being rebuilt, they are turned into parclo interchanges by removing some of the loop ramps (or in rare cases bridges will be added between adjacent loop ramps—see cloverleaf interchange for details). Various forms of parclo interchanges are used on the North Luzon Expressway in the Philippines . The configuration of parclo interchanges allows for

3565-457: A private venture, was the world's first limited-access roadway. It included many modern features, including banked turns , guard rails and reinforced concrete tarmac . Traffic could turn left between the parkway and connectors, crossing oncoming traffic, so it was not a controlled-access highway (or "freeway" as later defined by the federal government's Manual on Uniform Traffic Control Devices ). Modern controlled-access highways originated in

3720-467: A rate of one thousand per week on their way to California's interior, including the first large influx of Chinese immigrants to the U.S. The rush was so great that vessels were abandoned by the hundreds in San Francisco's ports as crews rushed to the goldfields. The unprecedented influx of new arrivals spread the nascent government authorities thin, and the military was unable to prevent desertions. As

3875-609: A reduction in deaths in a range from 20% to 50% on those sections. Speed, in Europe, is considered to be one of the main contributory factors to collisions. Some countries, such as France and Switzerland, have achieved a death reduction by a better monitoring of speed. Tools used for monitoring speed might be an increase in traffic density; improved speed enforcement and stricter regulation leading to driver license withdrawal; safety cameras; penalty point; and higher fines. Some other countries use automatic time-over-distance cameras (also known as section controls ) to manage speed. Fatigue

4030-447: A relatively straight ramp and is controlled by a traffic light. Running off the road on an entering ramp is much less likely than on an exiting ramp. Metering lights are a common feature on the entering ramps. The junction of Saskatchewan Highway 1 (east-west), Saskatchewan Highway 39 (south, part of the CanAm route) and Saskatchewan Highway 301 (north) is an A4 parclo. Highway 1 serves as

4185-461: A result, numerous vigilante groups formed to provide order, but many tasked themselves with forcibly moving or killing local Native Americans , and by the end of the Gold Rush, two thirds of the indigenous population had been killed. During this same time, a constitutional convention was called to determine California's application for statehood into the United States. After statehood was granted,

4340-538: A separate roadway or altogether eliminates it. In some parts of the world, notably parts of the US , frontage roads form an integral part of the freeway system. These parallel surface roads provide a transition between high-speed "through" traffic and local traffic. Frequent slip-ramps provide access between the freeway and the frontage road, which in turn provides direct access to local roads and businesses. Except on some two-lane freeways (and very rarely on wider freeways),

4495-494: A significant earthquake hazard. Among the more well-understood faults, as of 2014, scientists estimate a 72% probability of a magnitude 6.7 earthquake occurring along either the Hayward, Rogers Creek, or San Andreas fault, with an earthquake more likely to occur in the East Bay's Hayward Fault. Two of the largest earthquakes in recent history were the 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake . The Bay Area

4650-510: A similar system of express and local lanes for a maximum width of 21 lanes on a 2-mile (3.2 km) segment between Interstate 805 and California State Route 56 . In Mississauga , Ontario, Highway 401 uses collector-express lanes for a total of 18 lanes through its intersection with Highway 403 / Highway 410 and Highway 427 . These wide freeways may use separate collector and express lanes to separate through traffic from local traffic, or special high-occupancy vehicle lanes , either as

4805-523: A single San Francisco-based bank failed, while the region attempted to spur job growth by simultaneously undertaking two large infrastructure projects: construction of the Golden Gate Bridge , which would connect San Francisco with Marin County , and the Bay Bridge , which would connect San Francisco with Oakland and the East Bay. After the United States joined World War II in 1941, the Bay Area became

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4960-607: A single county, Alameda. Diverse assemblages adjoin in complex arrangements due to offsets along the many faults (both active and stable) in the area. As a consequence, many types of rock and soil are found in the region. The oldest rocks are metamorphic rocks that are associated with granite in the Salinian Block west of the San Andreas Fault . These were formed from sedimentary rocks of sandstone , limestone , and shale in uplifted seabeds. Volcanic deposits also exist in

5115-411: A special restriction on the innermost lane or a separate roadway, to encourage carpooling . These HOV lanes , or roadways open to all traffic, can be reversible lanes , providing more capacity in the direction of heavy traffic, and reversing direction before traffic switches. Sometimes a collector/distributor road , a shorter version of a local lane, shifts weaving between closely spaced interchanges to

5270-410: A stampede of wealth-seekers descending on Sutter's Mill . The Bay Area's population quickly emptied out as laborers, clerks, waiters, and servants joined the rush to find gold, and California's first newspaper, The Californian , was forced to announce a temporary freeze in new issues due to labor shortages. By the end of 1849, news had spread across the world and newcomers flooded into the Bay Area at

5425-649: A storm sank the San Agustin and killed between 7 and 12 people. On December 8, 80 remaining crew members set sail on the San Buenaventura , a launch which was partially constructed en route from the Philippines . Seeking the fastest route south, the expedition sailed past the Golden Gate, arriving at Puerto de Chacala, Mexico on January 17, 1596. The Bay Area estuaries remained unknown to Europeans until members of

5580-453: Is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway , motorway , and expressway . Other similar terms include throughway or thruway and parkway . Some of these may be limited-access highways , although this term can also refer to a class of highways with somewhat less isolation from other traffic. In countries following

5735-751: Is accepted by most local governmental agencies including San Francisco Regional Water Quality Control Board , Bay Area Air Quality Management District , the San Francisco Bay Restoration Authority , the Metropolitan Transportation Commission , and the Association of Bay Area Governments , the latter two of which partner to deliver a Bay Area Census using the nine-county definition. Various U.S. Federal government agencies use definitions that differ from their local counterparts' nine-county definition. For example,

5890-403: Is additionally known for the complexity of its landforms, the result of millions of years of tectonic plate movements. Because the Bay Area is crossed by six major earthquake faults , the region is particularly exposed to hazards presented by large earthquakes. The climate is temperate and conducive to outdoor recreational and athletic activities such as hiking, running, and cycling. The Bay Area

6045-544: Is considered as a risk factor more specific to monotonous roads such as motorways, although such data are not monitored/recorded in many countries. According to Vinci Autoroutes , one third of accidents in French motorways are due to sleepy driving. San Francisco Bay Area The San Francisco Bay Area , commonly known as the Bay Area , is a region of California surrounding and including San Francisco Bay , and anchored by

6200-672: Is controlled mainly by two-way stop signs which do not impose significant interruptions on traffic using the main highway. Roundabouts are often used at busier intersections in Europe because they help minimize interruptions in flow, while traffic signals that create greater interference with traffic are still preferred in North America. There may be occasional interchanges with other major arterial roads. Examples include US 23 between SR 15 's eastern terminus and Delaware, Ohio , along with SR 15 between its eastern terminus and I-75 , US 30 , SR 29 / US 33 , and US 35 in western and central Ohio. This type of road

6355-820: Is home to a complex network of watersheds, marshes, rivers, creeks, reservoirs, and bays that predominantly drain into the San Francisco Bay and Pacific Ocean. The largest bodies of water in the Bay Area are the San Francisco , San Pablo , and Suisun estuaries. Major rivers of the North Bay include the Napa River , the Petaluma River , the Gualala River , and the Russian River ; the former two drain into San Pablo Bay ,

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6510-468: Is host to five professional sports teams and is a cultural center for music, theater, and the arts. It is also host to numerous higher education institutions, including research universities such as the University of California, Berkeley , and Stanford University , the latter known for helping to create the high tech center called Silicon Valley . Home to 101 municipalities and 9 counties, governance in

6665-463: Is largely influenced by the cold California Current , which penetrates the natural mountainous barrier along the coast by traveling through various gaps. In terms of precipitation , this means that the Bay Area has pronounced seasons. The winter season, which roughly runs between November and March, is the source of about 82% of annual precipitation in the area. In the South Bay and further inland, while

6820-583: Is necessary to exit onto a surface road to transfer from one freeway to another. One example in the United States (notorious for the resulting congestion) is the connection from Interstate 70 to the Pennsylvania Turnpike ( Interstate 70 and Interstate 76 ) through the town of Breezewood, Pennsylvania . Speed limits are generally higher on freeways and are occasionally nonexistent (as on much of Germany's Autobahn network). Because higher speeds reduce decision time, freeways are usually equipped with

6975-450: Is not lower than 50 km/h [31 mph] and the maximum speed is not higher than 130 km/h [81 mph] (except Germany where no speed limit is defined). Motorways are designed to carry heavy traffic at high speed with the lowest possible number of accidents. They are also designed to collect long-distance traffic from other roads, so that conflicts between long-distance traffic and local traffic are avoided. According to

7130-431: Is provided with separate carriageways for the two directions of traffic). Principal arterials may cross through urban areas, serving suburban movements. The traffic is characterized by high speeds and full or partial access control (interchanges or junctions controlled by traffic lights). Other roads leading to a principal arterial are connected to it through side collector roads. In this view, CARE's definition stands that

7285-407: Is sometimes called an expressway . Freeways are usually limited to motor vehicles of a minimum power or weight; signs may prohibit cyclists , pedestrians and equestrians and impose a minimum speed. It is possible for non-motorized traffic to use facilities within the same right-of-way, such as sidewalks constructed along freeway-standard bridges and multi-use paths next to freeways such as

7440-480: Is specially sign-posted as a motorway and is reserved for specific categories of road motor vehicles." Urban motorways are also included in this definition. However, the respective national definitions and the type of roads covered may present slight differences in different EU countries. The first version of modern controlled-access highways evolved during the first half of the 20th century. The Long Island Motor Parkway on Long Island , New York , opened in 1908 as

7595-622: Is the ability to coordinate the traffic signals on the arterial in both directions independently. This is useful when there is more through-movement traffic on the arterial than turning traffic. There are B4 designs in Alberta : Three exist in British Columbia . In addition, the Solomon Pond Road interchange on I-290 in Northborough, Massachusetts , was converted from a B2 interchange to

7750-571: Is the presence of three conflict points in each direction for pedestrians and non-motorised vehicles, the first of which is a moderate speed, low visibility conflict. Caltrans favors this form for some recent projects, for example the reconstruction of I-880 and other highways in the San Francisco Bay Area and the Greater Los Angeles Area . They often replaced previous full cloverleafs. All exiting traffic for both directions has

7905-545: Is the result of several changes, including infrastructure safety and road user behavior (speed or seat belt use), while other matters such as vehicle safety and mobility patterns have an impact that has not been quantified. Motorways are the safest roads by design. While accounting for more than one quarter of all kilometres driven, they contributed only 8% of the total number of European road deaths in 2006. Germany's Federal Highway Research Institute provided International Road Traffic and Accident Database (IRTAD) statistics for

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8060-408: Is two lanes, but work has begun to make all of it four-lane.) These are often called Super two roads. Several such roads are infamous for a high rate of lethal crashes; an outcome because they were designed for short sight distances (sufficient for freeways without oncoming traffic, but insufficient for the years in service as two-lane road with oncoming traffic). An example of such a "Highway to Hell"

8215-581: The Bank of Italy (now known as the Bank of America ), had managed to retrieve the money from his bank's vaults before fires broke out through the city and was the only bank with liquid funds readily available and was instrumental in loaning out funds for rebuilding efforts. Congress immediately approved plans for a reservoir in Hetch Hetchy Valley in Yosemite National Park , a plan they had denied

8370-611: The Dartford Crossing (the furthest downstream public crossing of the River Thames ) or where it was not economic to build a motorway alongside the existing road such as the former Cumberland Gap . The A1 is a good example of piece-wise upgrading to motorway standard—as of January 2013, the 639-kilometre-long (397 mi) route had five stretches of motorway (designated as A1(M)), reducing to four stretches in March 2018 with completion of

8525-602: The Federal Communications Commission (FCC) which regulates broadcast, cable, and satellite transmissions, includes nearby Colusa , Lake and Mendocino counties in their " San Francisco - Oakland - San Jose " media market , but excludes eastern Solano County. On the other hand, the United States Office of Management and Budget , which designates metropolitan statistical areas (MSAs) and combined statistical areas (CSA) for populated regions across

8680-532: The Golden Gate or the estuaries, likely due to fog. Sir Francis Drake became the first European to land in the area and claim it in June 1579, when he landed at Drakes Bay near Point Reyes. Even though he claimed the region for Queen Elizabeth I as Nova Albion or New Albion , the English made no immediate follow up to the claim. In 1595, Philip II of Spain tasked Sebastião Rodrigues Soromenho with mapping

8835-680: The Hayward Fault Zone , Concord-Green Valley Fault , Calaveras Fault , Clayton-Marsh Creek-Greenville Fault , Rodgers Creek Fault , and the San Gregorio Fault . Significant blind thrust faults (faults with near vertical motion and no surface ruptures) are associated with portions of the Santa Cruz Mountains and the northern reaches of the Diablo Range and Mount Diablo . These "hidden" faults, which are not as well known, pose

8990-636: The Hayward fault , and the Diablo Range , which includes Mount Diablo and Mount Hamilton and runs along the Calaveras fault . In total, the Bay Area is traversed by seven major fault systems with hundreds of related faults, all of which are stressed by the relative motion between the Pacific Plate and the North American Plate or by compressive stresses between these plates. The fault systems include

9145-511: The Internet in the middle of the decade rapidly created a speculative bubble in the high-tech economy known as the dot-com bubble . This bubble began collapsing in the early 2000s and the industry continued contracting for the next few years, nearly wiping out the market. Companies like Amazon.com and Google managed to weather the crash however, and following the industry's return to normalcy, their market value increased significantly. Even as

9300-604: The North Pacific High through the Golden Gate, which creates the city's characteristic cool winds and fog . The microclimate phenomenon is most pronounced during this time, when fog penetration is at its maximum in areas near the Golden Gate strait, while the South Bay and areas further inland are sunny and dry. Along the San Francisco peninsula, gaps in the Santa Cruz Mountains , one south of San Bruno Mountain and another in Crystal Springs, allow oceanic weather into

9455-418: The Pacific Ocean on the west and the bay on the east and are characterized by their mountainous and woody terrain. Sonoma and Napa counties are known internationally for their grape vineyards and wineries , and Solano County to the east, centered around Vallejo , is the fastest growing region in the Bay Area. The " Peninsula " subregion includes the cities and towns on the San Francisco Peninsula, excluding

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9610-439: The Portolá expedition , while trekking along the California coast, encountered them in 1769 when the Golden Gate blocked their continued journey north. Several missions were founded in the Bay Area during this period. In 1806, a Spanish expedition led by Gabriel Moraga began at the Presidio, traveled south of the bay, and then east to explore the San Joaquin Valley . In 1821, Mexico gained its independence from Spain and

9765-414: The San Joaquin River Delta , causing a cooling effect in Stockton and Sacramento , so that these cities are also cooler than their Central Valley counterparts in the south. The Bay Area is home to a diverse array of wildlife and, along with the connected San Joaquin River Delta represents one of California's most important ecological habitats. California's Dungeness crab , Pacific halibut , and

9920-575: The Suncoast Trail along the Suncoast Parkway in Florida . In some US jurisdictions, especially where freeways replace existing roads, non-motorized access on freeways is permitted. Different states of the United States have different laws. Cycling on freeways in Arizona may be prohibited only where there is an alternative route judged equal or better for cycling. Wyoming , the second least densely populated state, allows cycling on all freeways. Oregon allows bicycles except on specific urban freeways in Portland and Medford . In countries such as

10075-440: The USS  Portsmouth into the bay and seized San Francisco, which was then known as Yerba Buena , and raised the American flag for the first time over Portsmouth Square . In 1848, James W. Marshall 's discovery of gold in the American River sparked the California Gold Rush , and within half a year 4,000 men were panning for gold along the river and finding $ 50,000 per day. The promise of fabulous riches quickly led to

10230-475: The United Kingdom new motorways require an Act of Parliament to ensure restricted right of way. Since upgrading an existing road (the "King's Highway") to a full motorway will result in extinguishing the right of access of certain groups such as pedestrians, cyclists and slow-moving traffic, many controlled access roads are not full motorways. In some cases motorways are linked by short stretches of road where alternative rights of way are not practicable such as

10385-424: The United Kingdom , do not distinguish between the two, but others make a distinction; for example, Germany uses the words Kreuz ("cross") or Dreieck ("triangle") for the former and Ausfahrt ("exit") for the latter. In all cases one road crosses the other via a bridge or a tunnel, as opposed to an at-grade crossing . The inter-connecting roads, or slip-roads , which link the two roads, can follow any one of

10540-559: The University of California, Berkeley Richard Walker claimed that "no other U.S. city-region is as definitionally challenged [as the Bay Area]." When the region began to rapidly develop during and immediately after World War II , local planners settled on a nine-county definition for the Bay Area, consisting of the counties that directly border the San Francisco , San Pablo , and Suisun estuaries : Alameda , Contra Costa , Marin , Napa , San Francisco , San Mateo , Santa Clara , Solano , and Sonoma counties. Today, this definition

10695-415: The Vienna convention , the motorway qualification implies that walking and parking are forbidden. A fully controlled-access highway provides an unhindered flow of traffic, with no traffic signals , intersections or property access . They are free of any at-grade crossings with other roads, railways, or pedestrian paths, which are instead carried by overpasses and underpasses . Entrances and exits to

10850-485: The gay rights movement . At the same time, parts of San Mateo and Santa Clara counties began to rapidly develop from an agrarian economy into a hotbed of the high-tech industry . Fred Terman , the director of a top-secret research project at Harvard University during World War II, joined the faculty at Stanford University in order to reshape the university's engineering department. His students, including David Packard and William Hewlett , would later help usher in

11005-401: The osprey . In 1927, zoologist Joseph Grinnell wrote that osprey were only rare visitors to the San Francisco Bay Area, although he noted records of one or two used nests in the broken tops of redwood trees along the Russian River . In 1989, the southern breeding range of the osprey in the Bay Area was Kent Lake , although osprey were noted to be extending their range further south in

11160-490: The shoulder at regular intervals. In the United States, mileposts usually start at the southern or westernmost point on the freeway (either its terminus or the state line). California , Ohio and Nevada use postmile systems in which the markers indicate mileage through the state's individual counties. However, Nevada and Ohio also use the standard milepost system concurrently with their respective postmile systems. California numbers its exits off its freeways according to

11315-561: The west coast of the United States , including populations residing in tributaries to San Francisco Bay. California Coast Chinook salmon were historically native to the Guadalupe River in San Francisco Bay, and Chinook salmon runs persist today in the Guadalupe River, Coyote Creek , Napa River , and Walnut Creek . Industrial, mining, and other uses of mercury have resulted in a widespread distribution of that poisonous metal in

11470-563: The 1980s an effort to re-introduce the species to the area began with the Santa Cruz Predatory Bird Research Group and the San Francisco Zoo importing birds and eggs from Vancouver Island and northeastern California, and there are now nineteen nesting couples in eight of the Bay Area's nine counties. Other once absent species that have returned to the Bay Area include Swainson's hawk , white tailed kite , and

11625-497: The A1(M) through North Yorkshire . The most frequent way freeways are laid out is by building them from the ground up after obstructions such as forestry or buildings are cleared away. Sometimes they deplete farmland, but other methods have been developed for economic, social and even environmental reasons. Full freeways are sometimes made by converting at-grade expressways or by replacing at-grade intersections with overpasses; however, in

11780-541: The Americas . The earliest Spanish exploration of the Bay Area took place in 1769. The Mexican government controlled the area from 1821 until the 1848 Treaty of Guadalupe Hidalgo . Also in 1848, James W. Marshall discovered gold in nearby mountains , resulting in explosive immigration to the area and the precipitous decline of the Native population . The California Gold Rush brought rapid growth to San Francisco . California

11935-470: The Bay Area at the time of first European contact were descended from Siberian tribes who arrived at around 1,000 BCE by sailing over the Arctic Ocean and following the salmon migration. However the current academic consensus is compatible with the oral tradition of the Ohlone and Miwok peoples, which suggests they have been living in the Bay Area for several hundreds if not thousands of years. At

12090-616: The Bay Area became part of the Mexican province of Alta California , a period characterized by ranch life and visiting American trappers. Mexico's control of the territory would be short-lived, however, and in 1846 a party of settlers occupied Sonoma Plaza and proclaimed the independence of the new Republic of California . That same year, the Mexican–American War began, and American captain John Berrien Montgomery sailed

12245-449: The Bay Area has experienced numerous political, cultural, and artistic movements, developing unique local genres in music and art and establishing itself as a hotbed of progressive politics . Economically, the post-war Bay Area saw large growth in the financial and technology industries, creating an economy with a gross domestic product of over $ 700 billion. In 2018 it was home to the third-highest concentration of Fortune 500 companies in

12400-509: The Bay Area involves numerous local and regional jurisdictions, often with broad and overlapping responsibilities. The Coyote Hills Shell Mound, the earliest known archaeological evidence of human habitation of the Bay Area estuaries, dates to around 10,000 BCE, with evidence pointing to even earlier settlement in Point Reyes in Marin County . It has been conjectured that the people living in

12555-572: The Bay Area their home, making the region a popular destination for birdwatching . Many birds are listed as endangered species despite once being common in the region. Western burrowing owls were originally listed as a species of special concern by the California Department of Fish and Game in 1979. California's population declined 60% from the 1980s to the early 1990s, and continues to decline at roughly 8% per year. A 1992–93 survey reported little to no breeding burrowing owls in most of

12710-506: The Bay Area, all naturally spawned anadromous steelhead populations below natural and manmade impassable barriers in California streams from the Russian River to Aptos Creek , and the drainages of San Francisco, San Pablo, and Suisun Bays are listed as threatened under the Federal Endangered Species Act . The Central California Coast coho salmon population is the most endangered of the many troubled salmon populations on

12865-480: The Bay Area, left behind by the movement of the San Andreas Fault, whose movement sliced a subduction plate and allowed magma to briefly flow to the surface. The region has considerable vertical relief in its landscapes that are not in the alluvial plains leading to the bay or in the inland valleys. The topography, and geologic history, of the Bay Area can largely be attributed to the compressive forces between

13020-996: The Bay Area: the Karkin of the Carquinez Strait , the Chochenyo of the East Bay , the Ramaytush of the San Francisco Peninsula , and the Tamien of the South Bay. The Miwok had two major groups in the Bay Area: the Bay Miwok of Contra Costa and the Coast Miwok of Marin and Sonoma . In 1542, Juan Rodríguez Cabrillo explored the Pacific coast near the Bay Area though the expedition did not see

13175-504: The Bay. The wild turkey population was introduced in the 1960s by state game officials, and by 2015 have become a common sight in East Bay communities. The Bay Area is well known for the complexity of its landforms that are the result of the forces of plate tectonics acting over of millions of years, since the region is located in the middle of a meeting point between two plates. Nine out of eleven distinct assemblages have been identified in

13330-480: The California scorpionfish are all significant components of the bay's fisheries . The bay's salt marshes now represent most of California's remaining salt marsh and support a number of endangered species and provide key ecosystem services such as filtering pollutants and sediments from the rivers. Most famously, the bay is a key link in the Pacific Flyway and with millions of shorebirds annually visiting

13485-724: The Central Valley and the Sierra Nevada. In 2014, a Bay Area-wide survey found osprey had extended their breeding range southward with nesting sites as far south as Hunters Point in San Francisco on the west side and Hayward on the east side, while further studies have found nesting sites as far south as the Los Gatos Creek watershed, indicating that the nesting range now includes the entire length of San Francisco Bay. Most nests were built on man-made structures close to areas of human disturbance, likely due to lack of mature trees near

13640-577: The East Bay receives oceanic weather that travels through the Golden Gate strait, and further diffuses that air through the Berkeley Hills , Niles Canyon and the Hayward Pass into the Livermore Valley and Altamont Pass . Here, the resulting breeze is so strong that it is home to one of the world's largest array of wind turbines . Further north, the Carquinez Strait funnels the ocean weather into

13795-835: The Pacific Plate and the North American plate. The three major ridge structures in the Bay Area, part of the Pacific Coast Range , are all roughly parallel to the major faults . The Santa Cruz Mountains along the San Francisco Peninsula and the Marin Hills in Marin County follow the San Andreas fault , The Berkeley Hills , San Leandro Hills and their southern ridgeline extension through Mission Peak roughly follow

13950-478: The San Francisco Bay Area are not officially delineated, and the unique development patterns influenced by the region's topography , as well as unusual commute patterns caused by the presence of three central cities and employment centers located in various suburban locales, has led to considerable disagreement between local and federal definitions of the area. Because of this, professor of geography at

14105-526: The San Francisco Bay Area, such as the Central Coast counties of Santa Cruz , San Benito , and Monterey , or the Central Valley counties of San Joaquin , Merced , and Stanislaus . The Bay Area is known for its natural beauty, prominent universities, technology companies, and affluence. The Bay Area contains many cities, towns, airports, and associated regional, state, and national parks, connected by

14260-409: The US, any at-grade intersection that ends a freeway often remains an at-grade intersection. Often, when there is a two-lane undivided freeway or expressway, it is converted by constructing a parallel twin corridor, and leaving a median between the two travel directions. The median-side travel lane of the old two-way corridor becomes a passing lane. Other techniques involve building a new carriageway on

14415-507: The United States refers to the A and B variants without numbers. Caltrans refers to the A2, B2, and A4 as types L-7, L-8, and L-9 respectively Parclo A2 and B2 configurations contain four ramps. On each side of the freeway there is a loop ramp and a directional ramp. In parclo A2, the loop ramps serve as on-ramps and the directional ramps serve as off-ramps. In parclo B2 the roles are reversed. Both on- and off-ramps require controlled intersections at

14570-476: The United States, allow for limited exceptions: some movable bridges , for instance the Interstate Bridge on Interstate 5 between Oregon and Washington , do require drivers to stop for ship traffic. The crossing of freeways by other routes is typically achieved with grade separation either in the form of underpasses or overpasses . In addition to sidewalks (pavements) attached to roads that cross

14725-531: The United States. The Bay Area is home to approximately 7.52 million people. The larger federal classification, the combined statistical area of the region which includes 13 counties, is the second-largest in California—after the Greater Los Angeles area—and the fifth-largest in the United States, with over 9 million people. The Bay Area's population is ethnically diverse: roughly three-fifths of

14880-693: The Vienna Convention. Exits are marked with another symbol: [REDACTED] . The definitions of "motorway" from the OECD and PIARC are almost identical. In the European Union , for statistical and safety purposes, some distinction might be made between motorway and expressway . For instance a principal arterial might be considered as: Roads serving long distance and mainly interurban movements. Includes motorways (urban or rural) and expressways (road which does not serve properties bordering on it and which

15035-484: The Whale , a humpback whale who entered San Francisco Bay twice on errant migrations in the late 1980s and early 1990s. Bottlenose dolphins and harbor porpoises have recently returned to the bay, having been absent for many decades. Historically, this was the northern extent of their warm-water species range. In addition to the many species of marine birds that can be seen in the Bay Area, many other species of birds make

15190-472: The area's largest city and the 13th-most populous in the United States . Despite its urban character, San Francisco Bay is one of California's most ecologically sensitive habitats, providing important ecosystem services such as filtering the pollutants and sediments from rivers and supporting a number of endangered species . In addition, the Bay Area is known for its stands of coast redwoods , many of which are protected in state and county parks. The region

15345-401: The arterial in order to allow more lanes on the offramps. This technique along with the ability to provide two-way signal progression along the arterial allows the parclo B4 to handle an extremely high flow of traffic along the arterial. Parclo designs with only two quadrants are commonly referred to as folded diamonds, due to their similarity with diamond interchanges . Sometimes the ramps in

15500-457: The arterial road (sometimes loop and directional ramps from the same side of the freeway will utilize the same intersection). The parclo A2 and B2 are commonly used on rural freeways such as Highway 402 and Highway 416 , where the ramps can be added without widening the street overpass/underpass to include deceleration lanes (normally needed on the A4 in order to safely enter the loop ramps that lead to

15655-416: The arterial road to the entrance ramps are made by right-hand turns, providing for a safer entrance to the freeway by eliminating left-hand turns into opposing traffic (which require queues waiting to make such turns). This also makes logical sense since freeways have a higher capacity than arterials and right-turn ramps serve effectively to absorb capacity and reduce traffic on the arterial. Some parclos have

15810-590: The bay has been significantly altered heavily re-engineered to accommodate the needs of water delivery, shipping, agriculture, and urban development, with side effects including the loss of wetlands and the introduction of contaminants and invasive species . Approximately 85% of those marshes have been lost or destroyed, but about 50 marshes and marsh fragments remain. Huge tracts of the marshes were originally destroyed by farmers for agricultural purposes, then repurposed to serve as salt evaporation ponds to produce salt for food and other purposes. Today, regulations limit

15965-436: The bay into north and south regions. In 1989, the federal Environmental Protection Agency defined the South Bay as the northern part of Santa Clara County and the southeastern part of San Mateo County. The Bay Area is located in the warm-summer Mediterranean climate zone ( Köppen Csb ) that is a characteristic of California's coast, featuring mild to cool winters with occasional rainfall, and warm to hot, dry summers. It

16120-496: The bay shallows as a refuge, is the most important component of the flyway south of Alaska . Many endangered species of birds are also found here: the California least tern , the California clapper rail , the snowy egret , and the black crowned night heron . There is also a significant diversity of salmonids present in the bay. Steelhead populations in California have dramatically declined due to human and natural causes; in

16275-479: The bay, with uptake in the bay's phytoplankton and contamination of its sportfish . Aquatic mammals are also present in the bay. Before 1825, Spanish, French, English, Russians and Americans were drawn to the Bay Area to harvest prodigious quantities of beaver , river otter , marten, fisher, mink, fox, weasel, harbor and fur seals and sea otter . This early fur trade, known as the California Fur Rush ,

16430-783: The bridge. The Queen Elizabeth II Bridge / Dartford tunnel at London Orbital is an example of this. London Orbital or the M25 is a motorway surrounding London , but at the last River Thames crossing before its mouth, motorway rules do not apply. (At this crossing the London Orbital is labeled A282 instead.) A few of the more common types of junction are shown below: There are many differences between countries in their geography, economy, traffic growth, highway system size, degree of urbanization and motorization, etc.; all of which need to be taken into consideration when comparisons are made. According to some EU papers, safety progress on motorways

16585-533: The capital city moved between three cities in the Bay Area: San Jose (1849–1851), Vallejo (1851–1852), and Benicia (1852–1853) before permanently settling in Sacramento in 1854. As the Gold Rush subsided, wealth generated from the endeavor led to the establishment of Wells Fargo Bank and the Bank of California , and immigrant laborers attracted by the promise of wealth transformed the demographic makeup of

16740-471: The cities of San Francisco , Oakland , and San Jose . The Association of Bay Area Governments defines the Bay Area as including the nine counties that border the estuaries of San Francisco Bay, San Pablo Bay , and Suisun Bay : Alameda , Contra Costa , Marin , Napa , San Mateo , Santa Clara , Solano , Sonoma , and San Francisco . Other definitions may be either smaller or larger, and may include neighboring counties which are not officially part of

16895-553: The city of San Francisco, natural and artificial topographical features direct the movement of wind and fog, resulting in startlingly varied climates between city blocks. Along the Golden Gate Strait , oceanic wind and fog from the Pacific Ocean are able to penetrate the mountain barriers inland into the Bay Area. During the summer, rising hot air in California's interior valleys creates a low pressure area that draws winds from

17050-492: The common European definition, a motorway is defined as "a road, specially designed and built for motor traffic, which does not serve properties bordering on it, and which: (a) is provided, except at special points or temporarily, with separate carriageways for the two directions of traffic, separated from each other, either by a dividing strip not intended for traffic, or exceptionally by other means; (b) does not cross at level with any road, railway or tramway track, or footpath; (c)

17205-447: The consolidation of toll barriers at points where onramps and offramps run alongside each other. A single large barrier can serve each onramp/offramp pair simultaneously, reducing construction and operation expenses at through junctions. When possible, such as at terminal junctions, trumpet interchanges are preferred since they only require one large toll barrier for all four on/off-ramps. Freeway A controlled-access highway

17360-494: The country, has five MSAs which include, wholly or partially, areas within the nine-county definition, and one CSA which includes eight Bay Area counties (excluding Sonoma ), but including neighboring San Benito , Santa Cruz , San Joaquin , Merced , and Stanislaus counties. The Association of Bay Area Health Officers (ABAHO), an organization that has fought local outbreaks of HIV/AIDS in 1980s and with COVID-19 pandemic and Delta cron hybrid variant (2020–22), consists of

17515-490: The destruction of tidal marshes, and large portions are currently being rehabilitated to their natural state. Over time, droughts and wildfires have increased in frequency and become less seasonal and more year-round, further straining the region's water security . According to the 2010 United States Census , the population of the nine-county Bay Area was 7.15 million, with 49.6% male and 50.4% female. Of these, approximately 2.3 million (32%) are foreign born. In 2010

17670-517: The early 1920s in response to the rapidly increasing use of the automobile , the demand for faster movement between cities and as a consequence of improvements in paving processes, techniques and materials. These original high-speed roads were referred to as " dual highways " and have been modernized and are still in use today. Italy was the first country in the world to build controlled-access highways reserved for fast traffic and for motor vehicles only. The Autostrada dei Laghi ("Lakes Motorway"),

17825-539: The end of the exit ramp to regulate the freeway traffic flowing onto the arterial. The parclo A4 is particularly well-suited to suburban areas with high traffic levels. Ontario freeways throughout much of the southern portion of the province, especially freeways in the Golden Horseshoe and Ottawa area, use the A4 parclo. These interchanges also exist on some highways in the Montreal area. One issue in suburban areas

17980-482: The first built in the world, connecting Milan to Lake Como and Lake Maggiore , and now parts of the A8 and A9 motorways, was devised by Piero Puricelli and was inaugurated in 1924. This motorway, called autostrada , contained only one lane in each direction and no interchanges. The Bronx River Parkway was the first road in North America to utilize a median strip to separate the opposing lanes, to be constructed through

18135-412: The first half of the 20th century. Italy was the first country in the world to build controlled-access highways reserved for fast traffic and for motor vehicles only. Italy opened its first autostrada in 1924, A8 , connecting Milan to Varese . Germany began to build its first controlled-access autobahn without speed limits (30 kilometres [19 mi] on what is now A555 , then referred to as

18290-469: The freeway ahead of the arterial road, while B designates that two ramps meet the freeway beyond the crossing. The number designates how many quadrants of the interchange contain ramps. In left-hand drive countries, the ramps function the same as in right-hand drive countries, but ramps with the same designation appear visually reversed. Common parclo configurations include the parclo A2 , parclo B2 and parclo A4 . The Department of Transportation in

18445-433: The freeway). The parclo A2 and B2 ramps are also usually longer and allow for higher speeds than their A4 counterparts because of rural land availability. It is possible to upgrade an A2 to an A4 by adding directional ramps, serving arterial-to-freeway traffic that would otherwise be forced to make a left turn to enter the loop ramps. The parclo A4 (also called "six-ramp partial cloverleaf") contains six ramps. On each side on

18600-428: The freeway, there is an (often multi-lane) exit ramp, followed by a loop ramp and directional ramp entering the freeway. The on-ramps are in the same configuration as a cloverleaf interchange, but there is one off-ramp for each freeway direction instead of two, typically requiring a controlled intersection where the off-ramp meets the arterial road. The parclo A4 is one of the most popular designs, as all movements from

18755-433: The freeway, while Highway 39/301 is the arterial road. The parclo B4 interchange superficially appears to be a mirror image of the parclo A4. However, the B4 design provides freeway-to-arterial ramps without traffic lights, while traffic turning left from the arterial must cross opposing traffic. Although this design has the potential to flood the arterial with more freeway traffic than the parclo A4, one particular advantage

18910-549: The growth of the technology sector transformed the region's economy, progressive politics continued to guide the region's political environment. By the turn of the millennium, non-Hispanic whites , the largest ethnic group in the United States, were only half of the population in the Bay Area as immigration among minority groups accelerated. During this time, the Bay Area was the center of the LGBT rights movement : in 2004, San Francisco began issuing marriage licenses to same-sex couples ,

19065-504: The highway are provided at interchanges by slip roads (ramps), which allow for speed changes between the highway and arterials and collector roads . On the controlled-access highway, opposing directions of travel are generally separated by a median strip or central reservation containing a traffic barrier or grass. Elimination of conflicts with other directions of traffic dramatically improves safety, while increasing traffic capacity and speed. Controlled-access highways evolved during

19220-566: The hit American pop song San Francisco (Be Sure to Wear Flowers in Your Hair) further enticing like-minded individuals to join the movement in the Bay Area and leading to the Summer of Love . In the proceeding decades, the Bay Area would cement itself as a hotbed of New Left activism, student activism , opposition to the Vietnam War and other anti-war movements , the black power movement , and

19375-511: The interior, causing a cooling effect for cities along the Peninsula and even as far south as San Jose. This weather pattern is also the source for delays at San Francisco International Airport . In Marin county north of the Golden Gate strait, two gaps north of Muir Woods bring cold air across the Marin Headlands , with the cooling effect reaching as far north as Santa Rosa . Further inland,

19530-408: The larger subregions, the East Bay includes a variety of enclaves, including the suburban Tri-Valley area and the highly urban western part of the subregion that runs alongside the bay, including Oakland. The " North Bay " includes Marin , Sonoma , Napa , and Solano counties, and is the geographically largest and least populated subregion. The western counties of Marin and Sonoma are encased by

19685-429: The latter two into the Pacific Ocean. In the South Bay, the Guadalupe River drains into San Francisco Bay near Alviso . There are also several lakes present in the Bay Area, including man-made lakes like Lake Berryessa and natural albeit heavily modified lakes like Lake Merritt . Prior to the introduction of European agricultural methods, the shores of San Francisco Bay consisted mostly of tidal marshes. Today,

19840-460: The mayor of Cologne . The German Autobahn became the first nationwide highway system. In Canada , the first precursor with semi-controlled access was The Middle Road between Hamilton and Toronto , which featured a median divider between opposing traffic flow, as well as the nation's first cloverleaf interchange . This highway developed into the Queen Elizabeth Way , which featured

19995-400: The motorway system, whilst a junction is a crossing between motorways or a split/merge of two motorways. The motorway rules end at exits, but not at junctions. However, on some bridges, motorways, without changing appearance, temporarily end between the two exits closest to the bridge (or tunnel), and continue as dual carriageways . This is in order to give slower vehicles a possibility to use

20150-439: The other. Other methods involve constructing a service drive that shortens the long driveways (typically by less than 100 metres (330 ft)). An interchange or a junction is a highway layout that permits traffic from one controlled-access highway to access another and vice versa, whereas an access point is a highway layout where traffic from a distributor or local road can join a controlled-access highway. Some countries, such as

20305-566: The public health officers of 9 Bay Area counties, in addition to the Central Coast counties of Santa Cruz , San Benito , and Monterey and the city of Berkeley . Among locals, the nine-county Bay Area is divided into five sub-regions: the East Bay , North Bay , Peninsula , city of San Francisco , and South Bay . The " East Bay " is the densest region of the Bay Area outside of San Francisco and includes cities and towns in Alameda and Contra Costa counties centered around Oakland . As one of

20460-497: The racial makeup of the nine-county Bay Area was 52.5% White (42.4% were non-Hispanic and 10.1% were Hispanic ), 23.3% Asian , 6.7% non-Hispanic Black or African American , 0.7% Native American or Alaska Native , 0.6% Pacific Islander , 5.4% from two or more races and 10.8% from other races. Hispanic or Latino residents of any race formed 23.5% of the population. The Bay Area cities of Vallejo , Suisun City , Oakland , San Leandro , Fairfield , and Richmond are among

20615-581: The ramps also have intersections fairly close to the freeway to allow traffic to continue on a rural country road (Jeannette's Creek Road / McKinlay Road) which formerly met Highway 2. One of the examples in Asia includes the Clark South exit in SCTEX , which is a two quadrant parclo interchange. Depending on traffic and land needs, hybrid designs, such as the parclo AB and parclo A3 , can be created. A notable example of

20770-477: The rate is higher than the risk on urban roads. Speeds are higher on rural roads and autobahns than urban roads, increasing the severity potential of a crash. According to ETSC, German motorways without a speed limit, but with a 130 km/h (81 mph) speed recommendation, are 25% more deadly than motorways with a speed limit. Germany also introduced some 130 km/h (81 mph) speed limits on various motorway sections that were not limited. This generated

20925-513: The region and even riots in Oakland. His name was symbolically tied to the Occupy Oakland protests two years later that sought to fight against social and economic inequality. By August 2023, San Francisco was in such severe decline that Mayor Matt Mahan of San Jose joked that one day the region might be renamed the "San Jose Bay Area", after its largest and most prosperous city. The borders of

21080-465: The region's high-tech revolution. In 1955, Shockley Semiconductor Laboratory opened for business in Mountain View near Stanford, and although the business venture was a financial failure, it was the first semiconductor company in the Bay Area, and the talent that it attracted to the region eventually led to a high-tech cluster of companies later known as Silicon Valley . In 1989, in the middle of

21235-412: The region's residents are Hispanic/Latino , Asian , African/Black , Indian , or Pacific Islander , all of whom have a significant presence throughout the region. Most of the remaining two-fifths of the population is non-Hispanic White American . The most populous cities of the Bay Area are San Francisco, Oakland , and San Jose , the latter of which had a population of 969,655 in 2023, making San Jose

21390-557: The region. In the early morning of April 18, 1906, a large earthquake with an epicenter near the city of San Francisco hit the region. Immediate casualty estimates by the U.S. Army 's relief operations were 498 deaths in San Francisco, 64 deaths in Santa Rosa , and 102 in or near San Jose, for a total of about 700. More recent studies estimate the total death count to be over 3,000, with over 28,000 buildings destroyed. Rebuilding efforts began immediately. Amadeo Peter Giannini , owner of

21545-586: The region. Between 1950 and 1960, San Francisco welcomed over 100,000 new residents, inland suburbs in the East Bay saw their populations double, Daly City 's population quadrupled, and Santa Clara 's population quintupled. By the early 1960s, the Bay Area and the rest of Northern California became the center of the counterculture movement . Telegraph Avenue in Berkeley and the Haight-Ashbury neighborhood in San Francisco were seen as centers of activity, with

21700-513: The region. Construction of the First transcontinental railroad from the Oakland Long Wharf attracted so many laborers from China that by 1870, eight percent of San Francisco's population was of Asian origin. The completion of the railroad connected the Bay Area with the rest of the United States, established a truly national marketplace for the trade of goods, and accelerated the urbanization of

21855-611: The right-turning (directional) on-ramp leave the arterial road after the exit ramp intersection. This configuration is often used when another road meets the freeway off-ramp and gives traffic from this road the option of turning right to use the directional on-ramp to enter the freeway. Traffic exiting the freeway to the arterial road is provided with a long, relatively straight exit ramp, preventing most speed-related rollovers. These exit ramps are also frequently multi-laned to accommodate traffic turning left, right, or going straight ahead in some cases. Traffic signals are commonly installed at

22010-643: The rights of light , air and access to highways, but not parkways and freeways; the latter two are distinguished in that the purpose of a parkway is recreation, while the purpose of a freeway is movement. Thus, as originally conceived, a freeway is simply a strip of public land devoted to movement to which abutting property owners do not have rights of light, air or access. Freeways, by definition, have no at-grade intersections with other roads, railroads or multi-use trails . Therefore, no traffic signals are needed and through traffic on freeways does not normally need to stop at traffic signals. Some countries, such as

22165-432: The side of a divided highway that has a lot of private access on one side and sometimes has long driveways on the other side since an easement for widening comes into place, especially in rural areas. When a third carriageway is added, sometimes it can shift a directional carriageway by 20–60 metres (50–200 ft) (or maybe more depending on land availability) as a way to retain private access on one side that favors over

22320-625: The sub port of Los Angeles. After World War II, the United Nations was chartered in San Francisco, and in September 1951, the Treaty of San Francisco to re-establish peaceful relations between Japan and the Allied Powers was signed in San Francisco, entering into force a year later. In the years immediately following the war, the Bay Area saw a huge wave of immigration as populations increased across

22475-645: The time of colonization, the Ohlone peoples in the Bay Area primarily lived on the San Francisco Peninsula, in the South Bay and in the East Bay, and the Miwok primarily lived in the North Bay, northern East Bay, and Central Valley. Ohlone villages were spread across the Peninsula, East Bay, South Bay, as well as further south into the Monterey Bay area. There were eight major divisions of Ohlone people, four of which were based in

22630-521: The tip of the San Francisco Peninsula, the city of San Francisco is not considered part of the "Peninsula" subregion, but as a separate entity. The term "South Bay" has different meanings to different groups: Writing in 1959 for the Army Corps of Engineers , the United States Department of Commerce defined the South Bay as comprising five counties, corresponding to their two-way division of

22785-491: The titular city of San Francisco. Its eastern half, which runs alongside the Bay, is highly populated, while its less populated western coast traces the coastline of the Pacific Ocean and is known for its open space and hiking trails. Roughly coinciding with the borders of San Mateo County , it also includes the northwestern Santa Clara County cities of Palo Alto , Mountain View , and Los Altos . Although geographically located on

22940-523: The west coast of the Americas. Soromenho set sail on Manila Galleon San Agustin on July 5, 1595 and in early November they reached land between Point St. George and Trinidad Head , north of the Bay Area, in the Lost Coast . The expedition followed the coast southward and on November 7 the San Agustin anchored in Drakes Bay, and claimed the region as Puerto y Bahía de San Francisco . In late November,

23095-419: The western counties in the Bay Area, leaving only Alameda , Contra Costa , and Solano counties as remnants of a once large breeding range. Bald eagles were once common in the Bay Area, but habitat destruction and thinning of eggs from DDT poisoning reduced the California state population to 35 nesting pairs. Bald eagles disappeared from the Bay Area in 1915, and only began returning in recent years. In

23250-459: The winter season is cool and mild, the summer season is characterized by warm sunny days, while in San Francisco and areas closer to the Golden Gate strait, the summer season is periodically affected by fog. Due to the Bay Area's diverse topographic relief (itself the result of the clashing tectonic plates ), the region is home to numerous microclimates that lead to pronounced differences in climate and temperature over short distances. Within

23405-406: The year 2010, comparing overall fatality rates with motorway rates (regardless of traffic intensity): The German autobahn network illustrates the safety trade-offs of controlled access highways. The injury crash rate is very low on autobahns, while 22 people died per 1,000 injury crashes—although autobahns have a lower rate than the 29 deaths per 1,000 injury accidents on conventional rural roads,

23560-443: Was European route E4 from Gävle to Axmartavlan , Sweden. The high rate of crashes with severe personal injuries on that (and similar) roads did not cease until a median crash barrier was installed, transforming the fatal crashes into non-fatal crashes. Otherwise, freeways typically have at least two lanes in each direction; some busy ones can have as many as 16 or more lanes in total. In San Diego, California , Interstate 5 has

23715-600: Was admitted as the 31st state in 1850. A major earthquake and fire leveled much of San Francisco in 1906. During World War II , the Bay Area played a major role in America's war effort in the Asiatic-Pacific Theater , with the San Francisco Port of Embarkation , of which Fort Mason was one of 14 installations and location of the headquarters, acting as a primary embarkation point for American forces. Since then,

23870-415: Was first reported in Redwood Creek at Muir Beach in 1996, has since been spotted in the North Bay's Corte Madera Creek , the South Bay's Coyote Creek , as well as in 2010 in San Francisco Bay itself at the Richmond Marina . Other mammals include the internationally famous sea lions who began inhabiting San Francisco's Pier 39 after the 1989 Loma Prieta earthquake and the locally famous Humphrey

24025-443: Was more than any other single factor, responsible for opening up the West and the San Francisco Bay Area, in particular, to world trade. By 1817 sea otter in the area were practically eliminated. Since then, the California golden beaver re-established a presence in Alhambra Creek , followed by the Napa River and Sonoma Creek in the north, and the Guadalupe River and Coyote Creek in the south. The North American river otter which

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