Roads And Traffic Conditions

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Racetrack Road

Racetrack Valley Road, Death Valley National Park.

California has a lot of roads. This is a guide to how to identify them, use them, and cope with the traffic encountered on them…

Freeways, State Highways, City Streets, Etc.

Road conditions, cross-traffic, speed limits, etc., depend very strongly on the type of road; the following are the main road types in California:

  • Freeways — these are the large multi-lane, limited access roads similar to the British Motorways or German Autobahns (but with a lot more frequent entrances and exits in urban areas). Pedestrians, mopeds, and bicycles are prohibited, with exceptions on the stretches of some rural freeways where the freeway is the only road between two towns. There are no stop signs, stop lights, traffic lights, etc. on freeways; cross traffic is prohibited; and, with few exceptions, the freeways are completely divided. Only emergency stopping or parking is allowed on the shoulders. Speed limits are usually 55 or 65 MPH; rural freeways often have 70 MPH limits.
    California roadside call box.

    California roadside call box.

    Freeways usually come in three types — Federal (or US) roads like US 101; the Interstate routes like Interstate 80; and state highways like State Route 4 in the Bay Area. To all intents and purposes, all freeways, whether US, State, or Interstate, look the same and have the same rules throughout the state. If the road you’re on changes from a highway to a freeway (or vice versa), you will be told this explicitly by a series of roadside signs. Longer freeways often have rest areas every so often; these usually have restrooms (toilets) and space to walk your dog or eat lunch, etc. Some also have licensed vans or vending machines selling snacks, but rest areas do not have permanent food stores or cafes, nor is gas available. Many rest areas also have some sort of historical marker or natural history plaque relating to the surrounding area; these are usually worth reading to get some sort of sense of the country you’re driving through (and take note of the signs warning you of the rattlesnakes in the surrounding grass — these are not jokes or tourist curios…). Freeways are patrolled by the California Highway Patrol (CHP), both for traffic violations and things like car breakdowns and accidents. Other police have the authority to book you for breaking the traffic laws on freeways passing through their territory, but this is not common.

    Many rural freeways and highways are equipped with road-side emergency phones or call-boxes; these are usually yellow boxes and posts, often with a solar power panel on top; these are for breakdowns and accidents only. Emergency call-box spacing and availability varies widely from freeway to freeway, and area to area.

  • Highways — these are usually the larger rural roads, corresponding to the British “A” roads. They come in all sorts of shapes and sizes, and run the gamut from US Highways to State Highways to County Highways. Many of the larger ones (e.g. US 395 in parts of the Owens Valley, or bits of US 50 between Sacramento and Placerville) are freeways in all but name. What distinguishes them from freeways is usually the fact that cross-traffic, stop lights (and signs), and such things are allowed; in many rural areas, the highway is the main street for the towns along it, meaning that speed limits are also very variable. Some highways (or parts of highways, like US 395 again) are well-maintained, multi-lane, divided roads with rest stops every so often; many others are the classic two-lane black-top County Routes, in various states of repair. Some of the larger (US and State) highways have emergency call boxes as described above.State and federal highways are patrolled by the CHP and (sometimes) local police; county highways are usually patrolled by county sheriff’s deputies and local police. Note: if the above is a bit confusing, remember: all Interstate routes (e.g. I-580 or I-80) are freeways, but not all US or State routes are freeways (most state routes are highways, in fact).
  • Parkways and expressways — in most cases, these are what amount to short urban or suburban highways. Usually multi-laned and semi-divided, they have stop lights, cross traffic, etc., but usually have higher speed limits than the surrounding suburban roads.
  • Urban and suburban roads — these are just the normal roads in cities and suburbs. Speed limits are usually 25 MPH, very occasionally 30 or 35 MPH, sometimes 15 MPH.
  • Note: the terms “turnpike” or “pike“, though common elsewhere in the US, aren’t used here at all, and don’t have any particular meaning for locals.

Road Naming & Direction Conventions

Official road naming and marking conventions don’t vary much throughout the state; unofficially, though, the way people refer to the various roads does vary quite a bit.

In Northern California, and the San Francisco Bay Area in particular, larger freeways are usually informally referred to by their number, e.g. “I-80” (pronounced “eye eighty” or “Interstate eighty”), “101” (“one-oh-one”), “I-5” (“eye-five”, or occasionally “Interstate five”), “580” (“five-eighty”), rather than the corresponding freeway names — “Eastshore Freeway” (I-80 between Bay Bridge and San Pablo Bay), “The Bayshore Freeway”, “The Westside Freeway”, and “the Macarthur Freeway”, respectively. Using the official freeway names will confuse a lot of Bay Area residents (how many know the official name for Interstate 680, for example? I had to look it up, despite being intimately familiar with the freeway…). On the other hand, Southern Californians (especially Los Angelenos) tend to use the names more than the numbers; for example “The Ventura Freeway” for US 101, the “Santa Monica Freeway” for I-10, etc. Additionally, when giving freeway numbers, Northerners will give them without the definite article or the word “freeway”, e.g. “Follow 580 east until you cross 680”; Southerners will typically use “the” and sometimes the word “freeway”, e.g. “Take the 405 until you get to the Ventura Freeway”. This varies a bit around the state, so it’s a good idea to have some idea of the name as well as the number. All freeways and highways are marked with the number even when there’s no name, so it’s always useful to know the number — that number will almost always appear on maps even if the name doesn’t.

Smaller urban highways and parkways are usually known by name — Ashby Avenue rather than State Route 13, or San Pablo Avenue rather than SR 123, for example — but even on these roads the number will be signposted regularly (though locals sometimes still have trouble remembering the numbers without the name). Unlike freeways and major highways, these smaller roads may not be identified by number on maps — commonly, only the name appears.

signs1Officially, Federal freeways and highways are identified with white and black shields, the route number in black on a white shield bordered by black. If you’ve ever seen the old Route 66 television show, that Route 66 sign is a classic example of this. Federal / US routes are usually identified on maps and in publications in the form “US 101”, or the shield with the number in it, or similar. All Interstates are identified with a red, white, and blue shield: white numbering on a blue background, with a red top to the shield (also, the shield’s shape is different to the US route shields). On maps or in official publications Interstate freeways are usually referred to in the form “I-880” or “Interstate 880”, or the number-on-a-shield form. State Routes are identified with a green and white, rounded-triangular shield: white numbering on a green background with white borders. State routes and highways are referred to in a wide variety of ways in maps and publications; many do not use the California state green shield markings but use ovals or squares. County roads and highways are identified in various ways, but virtually all identifications include a letter, e.g. “A17” or “J14”. These letters do not seem to correspond to the county name, unfortunately.

With a few well-known exceptions that I’m aware of (e.g. Interstate 110 and State Route 110 in the LA region), all US, Interstate and State route numbers are unique within the state — there is no US 4 or Interstate 4 in California because there is already a State Route 4 (and in the case of the routes 110, they’re actually two ends of the same road). This is not true for County routes (there’s both an A17 and a J17 in California, in Shasta County and Merced County respectively), nor is it true across the US as a whole — there are separate Interstate 280s in at least California and New Jersey.

Freeways and highways are usually marked periodically with signs giving the freeway number and general direction; this is particularly common after major interchanges or freeway entrances. The direction given (“North”, for example), is the direction of the freeway as a whole, not necessarily the direction the freeway seems to be traveling in at that particular location. This can be very confusing if you don’t know the ultimate destination of the freeway — there’s a classic spot on Interstate 80 in Berkeley where the signs say that this particular stretch of road is both “I-80 East” and “I-580 West” — but you’re actually driving north at this point… (I-80 is heading north here as the first step on its journey all the way east to New York, while 580 has joined I-80 on its way north for a few miles before splitting again from I-80 and heading west towards the Richmond Bridge and its ultimate destination, San Quentin). This same point holds true for freeway and highway destination and exit signs in general — if the area you’re going to isn’t explicitly on the sign, you will need to know which direction the freeway or highway you need to exit to is ultimately going, or the ultimate destination city. This can be very difficult to determine.

California has a reasonably logical freeway exit numbering system (established only in 2002!), based on distance from the start of the freeway. For example, “Exit 425” will be 425 miles from the start of the freeway; Caltrans uses a letter suffix for close-together exits, e.g. “Exit 425A” and “Exit 425B”. This scheme gives you a good way to quickly work out how far you have to go to the exit if you forgot your GPS or whatever. Increasing numbers of maps, GPS units, automated directions, etc., have incorporated these exit numbers, and even locals have started using them a bit.

California also doesn’t have a usable milepost system — the mileposts that do exist typically measure mileage from the nearest county line, which (obviously) isn’t all that useful to most people, and the mileposts are usually small and hard to see.

For a really excellent comprehensive look at California’s highways — the numbering, their history, status, routes, etc. — go to the California Highways Home Page. Great stuff!

Traffic Conditions and Traffic Reports

Traffic conditions in the major Californian urban and suburban areas generally vary from busy-but-fast-moving to totally choked up. Rush hour (“commute”) traffic in Los Angeles and the San Francisco Bay Area is often very bad, day after day — L.A. is consistently rated as having the worst traffic in the U.S.; San Francisco Bay Area traffic is either second or third worst in the country depending on who you ask. Traffic on major rural freeways such as Interstate 5 or State Route 99 can also be surprisingly heavy, especially during holiday periods.

Google’s traffic reports on Google Maps for LA and the San Francisco Bay Area are pretty accurate and up to date (at least in my experience), and Android or iPhone maps based on that info are also useful for driving — unless you’re out of range of WiFi and you’re on a non-US plan that charges an arm and a leg for data roaming. Local media in the major metropolitan areas also typically have good real-time traffic condition web sites; more usefully for when you’re actually driving and don’t want to take your eyes off the road to fiddle with the iPhone, many radio stations give out traffic information every so often. Two that I use in the Bay Area are, for example, KCBS AM 740, which does this every ten minutes, 24 hours a day, and KQED FM (88.5) which does it every ten to 15 minutes during rush hours.

Traffic reports are useful, but (especially in the Bay Area) geography means there’s often no real alternative to a particular route (that damn Bay gets in the way…), so being told that (say) all west-bound traffic on the Bay Bridge is completely stopped due to an earlier accident isn’t always helpful except perhaps to tell you to stay where you are if you can until the traffic gets better; in other cases, you need to be a local to know useful alternative routes around the traffic problems. Under certain conditions, it is often quicker to bypass the urban freeways. This is particularly true for parts of LA and the Bay Area, and is often referred to as “surfacing” or “taking a surface route”. This can be tricky and dangerous unless you know what you’re doing — many “obvious” routes take you through the sort of area where it might be dangerous to have your car break down, or where traffic conditions are even more unpredictable. And others, of course, will probably have the same idea, leading to traffic gridlock on the surface roads.

In the Bay Area, Los Angeles, and most of the rest of the state, Caltrans has a special phone number, 511 (callable without a prefix from any in-state location) which contains recorded information about traffic delays, public transit status, etc. This information is also available at

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A gratuitous video of the old San Francisco – Oakland Bay Bridge I made a few years ago before it was replaced and demolished:


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