California Road Network

By | October 13, 2022

The road network in California is often outdated, and due to ongoing budget shortfalls, it is also in poor condition. In 2013, all of California’s metropolitan areas were in the top 20 worst urban roads in the United States. The enormous traffic pressure on the road network also plays a role in this. There are three major roads running from north to south, only one of which is entirely a freeway is. These are US 101, I-5 and SR-99, counting inland from the sea. One diagonal is I-15, which runs from San Diego to Nevada. In addition, 4 highways run east-west, from north to south I-80, I-40, I-10 and I-8. A large highway network has been developed in the various major urban areas. However, contrary to popular belief, the various conurbations such as San Francisco and Los Angeles score very low in the number of lane kilometers per inhabitant, which are among the lowest in the United States, which automatically leads to a very high traffic density in urban areas. leads.

The network of US Highways is particularly thin in California, with only a limited number of US Highways in the state, after many roads were renumbered in the 1960s. The most famous of these is U.S. Route 66, now called I-40 and I-10. Many State Routes in urban areas have been expanded to freeways and are part of the highway network. Some State Routes handle more traffic than Interstate Highways, especially in Los Angeles.

  • Bittranslators: State overview of California, including geography, economy, population and history as well as introduction to major cities of California.

Road manager

The highway authority of the Interstate, US and State Highways is the California Department of Transportation, abbreviated Caltrans. [5] Caltrans has its origins in the Bureau of Highways founded in 1895. At the time, the roads were still a task of the local authorities, the office had the task of mapping the road network and was housed in the Department of Highways in 1896. California was one of the first states in the western United States to establish such a department. In 1961, this merged into the Highway Transportation Agency, which was renamed the Transportation Agency in 1965. In 1973, the current California Department of Transportation (Caltrans) was established.

Caltrans operates a network of 24,426 kilometers of state highway and more than 80,000 lane kilometers. The state operates more than 24,000 bridges, mostly small bridges and viaducts, as well as the major iconic bridges around San Francisco. The condition of the bridges deteriorated the fastest of all states in 2017.

Caltrans is the only highway authority in the United States that does not generally apply mile markers to its roads, but uses a system of postmiles per county.

  • Deluxesurveillance: Nickname of California as The Golden State. Also covers geography, history, economy, politics and administration of the state.

Interstate Highways

Some major Interstate Highways run in California. Interstate 5 runs from the Mexico border at San Diego through Los Angeles and Sacramento to the Oregon border. Interstate 8 begins in San Diego and runs parallel to the Mexican border to Arizona. Interstate 10 begins at the Pacific Ocean in Santa Monica and runs through Los Angeles to Arizona. Interstate 15 is the north-south route through the Inland Empire, from San Diego to the Nevada border. The Interstate 40 is relatively short in California, splitting off I-15 at Barstow and running into northern Arizona. Finally, Interstate 80 is the main route from San Francisco via Sacramento through the Sierra Nevada to the Nevada border.

A number of auxiliary routes of 3-digit Interstate Highways complement the network, mainly in metropolitan areas. Iconic are Interstate 280 between San Jose and San Francisco and Interstate 405 through the Los Angeles area. I-405 is the busiest highway in the United States.

US Highways

The US Highways largely disappeared from California with the renumbering of 1964. Major corridors have been replaced by Interstate Highways, except for US 99, which has been renumbered State Route 99 and is a long freeway. The best-known historic US Highway, US 66 in California, no longer exists in California under that number since 1974. The two best known remaining US Highways in California are the US 101, which runs along almost the entire west coast and includes the Golden Gate Bridge in San Francisco. The US 50 is an east-west link through the Sierra Nevada, from Sacramento to Lake Tahoe on the Nevada border. In eastern California, US 395 still has ongoing importance.

State routes

The state routes form the secondary road network of California, but can be of various design. In urban areas, state routes are regularly operated as freeways that are not inferior to the Interstate Highways. Given its extensive urban areas, California has one of the longest freeway lengths in the United States made up of state routes.

The numbering of state routes does not say much about importance. The state routes with a number higher than 100 are often the shorter routes, but these can also be designed as freeways. State routes with a number higher than 200 are often short links of little importance, but here too some routes are performed as freeway.

Because of the fairly large network of Interstate Highways, state routes outside the metropolitan areas often form no more than regional connections. This is also because California’s population is largely concentrated in a few metropolitan areas connected by Interstate Highways. State Route 99 is the longest non-interstate highway in the United States, running from just north of Los Angeles to Sacramento.

HOV lanes

See also Los Angeles HOV system and San Francisco Bay Area HOV system.

In California, there has been a strong focus on HOV lanes, also known as carpool lanes, since the 1970s. Initially, these were mainly bus lanes along freeways, but from 1980 the left hard shoulder was widely converted into a fifth lane, which was then an HOV lane. A large part of California’s highways was constructed in the 1950s-60s with 2×4 lanes and left hard shoulder, so that many highways could be provided with an HOV lane cheaply. However, after 1990, investments increased sharply due to the construction of flyovers at junctions connecting the HOV lanes of various highways. Previously, carpoolers often had to cross 5 lanes to reach the exit on the right side of the freeway. With separate flyovers, carpoolers can continue to drive on the left in the HOV lane.

The Los Angeles region in particular has an extensive network of HOV lanes. The number of carpoolers has not grown since 1980, despite billions of dollars being invested. In 1980 there were 1.8 million people who carpooled. This rose to 2 million in 1990 and then remained stable until the 2008 recession. In the recession this shrank to 1.8 million. However, there has been no new growth in the number of carpoolers since the recession. However, between 1980 and 2014, the number of commuters traveling alone rose from 7.1 to 12.7 million.


Striking in California is the very minimal road lighting on freeways in urban areas. In many places there is only limited lighting in the verge at entrances and exits. Major interchanges are sometimes illuminated by the tall light poles, but most of the freeways, including freeways with 5 lanes in each direction, are essentially unlit. However, there is a lot of ambient light from companies and billboards, so it is never very dark on these highways.

Maximum speed

The speed limit in California is usually 55 mph on two-lane roads, 65 mph on divided highways and 70 mph on rural freeways. Vehicles towing a trailer are not allowed anywhere faster than 55 mph, which means California has a lower speed limit for trucks than elsewhere in the United States.


Although California is often seen as the mecca of freeways, California was not the first state where highways were built. The first American highways were built in and around New York City. In the 1920s, California had a relatively small population of just over 3 million. From the 1930s, several major bridges opened in and around San Francisco, culminating in the iconic San Francisco – Oakland Bay Bridge in 1936 and the Golden Gate Bridge in 1937. At that time, short access routes also opened to these bridges that later became part of freeways., specifically Interstate 80.

In Los Angeles, the Ramona Parkway opened in 1935, a kind of expressway that would later become part of the San Bernardino Freeway (I-10). In 1940, the Arroyo Seco Parkway opened between Los Angeles and Pasadena. This later became part of State Route 110 and is generally considered Los Angeles’ first freeway. In the 1940s, some towns and cities opened up short stretches that later became part of long freeways, such as the Santa Ana Freeway (I-5) southeast of Los Angeles in 1947 and portions of the Bayshore Freeway in San Jose and San Jose. Francisco in 1947. In 1946, the first section of Interstate 80 opened northeast of sacramento. In 1949, the Four Level Interchange opened in Los Angeles, the world’s first stack interchange.

From the 1950s, freeways were built on a larger scale, especially in the regions of Los Angeles, San Diego and San Francisco. Various short freeways were also constructed around other smaller towns. The first longer corridors to be completed were Interstate 880 between Oakland and San Jose in 1958, the Santa Ana Freeway between Los Angeles and Irvine in 1958, the first part of the Hollywood Freeway in 1958, the San Bernardino Freeway between Los Angeles and San Bernardino in 1959 and the Bayshore Freeway between San Jose and San Francisco in 1960.

The vast majority of freeways in California were opened between 1955 and 1975. Only in later growth areas did highways open into the 1980s and 1990s, particularly around San Jose, Orange County, and San Diego. By 1972, the entirety of Interstate 10 between Los Angeles and Arizona was completed, followed by Interstate 80 between San Francisco and Nevada in 1974. Most urban freeways were completed in the mid-1970s. However, between 1970 and 2010, California’s population grew from 20 million to 38 million, causing the highway network to become heavily congested.

In 1964, a major renumbering of California’s highway network was implemented, with many US highways being scrapped in the state. Particularly prominent was the complete cancellation of US 66 and US 99. Originally California had no exit numbering. This was only gradually introduced from around 2006. Through the San Joaquin Valley in central California, between Los Angeles and Sacramento, US 99 was the primary route, passing through the towns of Bakersfield, Fresno, Modesto, and Stockton. A number of parts of this route were already constructed in the 1950s and 1960s. After the creation of the Interstate Highway system in 1956, it was decided to make Interstate 5 to construct an entirely new route between Los Angeles and Sacramento. However, the construction of this did not start immediately, so that the US 99, later the State Route 99, was the main route for a long time. However, the conversion of SR-99 to a freeway was slow and fragmented, unlike I-5, which opened 400 kilometers at a rapid pace between 1966 and 1971. This highway was completed in 5 years. Parts of State Route 99 are still not a full freeway.


There is chronic congestion in Los Angeles and the San Francisco Bay Area, and to a somewhat lesser extent in San Diego and Sacramento. The highways in these urban areas have often not been upgraded since the 1970s, with the exception of the creation of a large number of HOV lanes in Los Angeles, the Los Angeles HOV system. These were not real widenings, in most cases the lanes were narrowed and the left hard shoulder was transformed into a HOV lane.

A large-scale widening of the motorway network in these urban areas cannot be foreseen. Congestion is managed better by constructing express lanes and HOT lanes, toll lanes that are guaranteed to be free of congestion due to dynamic pricing. If the supply becomes too high, the toll rates are increased to discourage less urgent trips (pricing off lower value trips). In the San Francisco Bay Area in particular, efforts are being made to convert HOV lanes into HOT lanes. In the Los Angeles area, the plans are less concrete. California cities have large amounts of HOV lanes, but carpooling is a downward trend, as a result of which this capacity is used less. In addition, a large proportion of carpoolers are family members who would drive together anyway, even if there are no HOV lanes. The traffic-reducing effect of HOV lanes is therefore not as great as the amount of traffic in the HOV lanes suggests.

In Central California, it is planned to widen the entire corridor of State Route 99 between Bakersfield and Sacramento to a minimum of 2×3 lanes. However, this is a long-term project that will be implemented in phases. Significant completion is not expected before 2030. A widening of the I-5 is not necessary, this highway does not serve any major cities except Stockton between Los Angeles and Sacramento and is therefore significantly quieter than State Route 99.

A point of concern in California is the poor quality of the roads. The road surface consists of worn and uneven concrete slabs and needs to be replaced on a large scale. Road lighting in urban areas can also be called mediocre and traffic signaling is nowhere to be found at all. Rush hour lanes are also unknown in California.

Road numbering

All roads administered by the state of California ( State Routes, US Highways, and Interstate Highways ) are numbered. These three types of roads are numbered in one numbering system, so a number does not appear twice. For example, there is an Interstate 80, but no State Route 80. Or the numbering goes from State Route 4 to Interstate 5 and on to US 6 and State Route 7 again.

Several songs are skipped. These are unbuilt or deleted routes. In addition, songs are occasionally skipped. The numbering ranges from 1 to 980, although the primary number layer does not extend beyond 285. Higher numbers are Interstate Highways, US Highways and incidentally assigned high numbers of State Routes. The US Highways in California have a different road number shield than elsewhere in the United States.

The longest route is US 101 with a length of 1,300 kilometers. The longest State Route is State Route 1 with a length of 1,055 kilometers.


California’s urban areas experience widespread congestion. The congestion is among the worst in the country. This is mainly because the highway network is designed for a considerably smaller population than is the case today. Most major cities in California have relatively few lane miles relative to population compared to other metropolitan cities in the US. Los Angeles ranks 31st in the list of 39 largest cities in the United States by lane mileage, and 30% less than the average American metropolis. In the San Francisco Bay Area, this is even lower. San Diego, on the other hand, scores higher, with 17th place. [8]

Because the highways usually have 2×4 or more lanes, congestion is often limited to slow driving. In case of incidents, there are usually enough lanes left so that the traffic is not immediately blocked. Because traffic does travel slowly over large distances, often tens of kilometers, the delay times can still increase considerably. In addition, the rush hour lasts very long, especially in Los Angeles, where the first traffic jams arise at half past five in the morning, and it only calms down after 11 o’clock. At 2 pm the crowds start again, which lasts until after half past six in the evening. Traffic flow is much better in San Diego.

California Road Network