What is the hierarchy of roads in your country like?
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In the U.S., we have a hierarchy of highways maintained by different levels of government.
Interstate Highways
I-29 south of Fargo by
tvdxer, on Flickr
At the top of the hierarchy are
interstate highways. Modeled off similar roads in Europe and the brainchild of the Eisenhower administration in the 1950's, these are virtually always limited-access, lacking stop signs, and in theory, would permit one to drive uninterrupted across the country as long as they had enough fuel if it were not for traffic, bathroom breaks (although I suppose those would be taken care of if you were in a motorhome), or sleep requirements.
A unique thing about all levels of highway in the United States - but perhaps interstates especially - is that they can run through and divide cities, either elevated, in tunnels, or at ground level. Numerous accusations of neighborhood destruction, especially affecting minorities, have been lodged against the people behind the Interstates.
Pedestrians, cyclists, and slow motorized vehicles are not allowed on the Interstates.
Interstates themselves are given two-digit numbers. If they are odd, they run from east to west; if even, north to south. The highways are numbered in a non-serial west-to-east and south-to-north order. So I-5 runs from the Mexican to the Canadian border near the Pacific Coast; I-95 runs from Maine to Florida; I-10 runs from Florida to California; and I-94, from Michigan to Montana. There also exists many three-digit "interstates" which serve as ring roads and other metropolitan limited-access freeways.
Interstates have
rest areas, but that's it. No state-franchised restaurants (like "Autogrill" in Italy), because they are simply not necessary when a multiplicity of restaurants, chain and independent, are just off most exits.
For all the grilling American infrastructure receives, interstates provide the most comfortable driving experience of any highway I've been on. They're separated - sometimes one does not see the traffic going in the opposite direction (because it is on a separate road hidden behind trees), broad shoulders in case anything goes wrong, high speed, straight, and uncrowded outside metropolitan areas (70 mph in Minnesota), and most of the interstate system is toll-free. It is a true pleasure to be able to set your cruise control and just relax.
The interstate highway system, is, to my knowledge, maintained by the individual state Departments of Transportation with federal funds.
U.S. Highways
US-2 Entering Proctor by
tvdxer, on Flickr
Far down the totem pole are U.S. Highways, which served the same function as interstate highways prior to their existence. Much or most of the U.S. Highway system does not have limited access, consists of two lanes with (sometimes very broad) shoulders, and often crosses through small towns, sometimes acting as their main street complete with wide sidewalks and street ornamentation. Pedestrians and cyclists are not prohibited from U.S. highways, at least not as a rule, and cycling down them can actually be quite a pleasure if you take care.
However, in medium and large cities, U.S. highways can begin to resemble interstates with limited-access portions.
In the suburbs, "access roads" run along U.S. highways providing entry to the parking lots of malls, stores, restaurants, office parks, and other facilities. Some of these businesses are located directly off U.S. highways. This is not to mention the small towns which U.S. highways form a main street to, with lowered speed limits (30 mph / 50 kph seems common), parking lanes, and municipal signage. Sometimes municipalities rename U.S. highways within their boundaries.
The speed limit is generally, but not always, lower than interstates - in Minnesota, 55 mph (90 kph) seems to be the speed limit most often assigned to rural U.S. highway.
Many U.S. highways are recommendable for road trips, as you still get to see scenery and "culture" that is often missing from interstate routes. Because of their interstate ("U.S.") nature, such highways can cross as many states and regions as interstate highways. For example, US 61 goes from Minnesota to Louisiana.
Sometimes portions of U.S. highways are co-signed with interstate highways, which means driving an entire U.S. highway will entail entering and exiting an interstate highway.
State Highways
Minnesota Highway 1 by
tvdxer, on Flickr
Minnesota Highway 23 (in Duluth) by
tvdxer, on Flickr
From what I've seen of roads, state highways seem to resemble U.S. highways, except they are contained to one state, while U.S. highways cross states.
State highways can be windy two-lane roads in the middle of nowhere, as is MN 1; or they can be limited-access, high-speed, multi-lane urban highways, as is MN 55 (Hiawatha Road in Minneapolis). They often form arterials when in small-to-medium-sized cities: for example, MN 23 in the West Duluth neighborhood of Duluth, Minnesota is a two-lane, 30 mph / 50 kph road with adequate on-road parking and biking in shoulders, and numerous sidewalk-fronting businesses and homes.
Sometimes portions of state highways are co-signed with interstate highways, which means driving an entire state highway will entail entering and exiting an interstate and/or U.S. highway.
County Highways
County Road 696, St. Louis County by
tvdxer, on Flickr
Most American states are divided into
counties. In Minnesota, the County is responsible for administering criminal justice on behalf of the state and handling civil suits; law enforcement in rural areas; administering social service programs (food stamps, emergency cash assistance, etc.); and a variety of other tasks.
County highways, then, are highways that fall under the auspices of the county. In my county (St. Louis, Minnesota), as well as the next one over (Carlton), county roads range from four-lane paved roads with stoplights to rural gravel surfaces. They are often used as streets by residents of rural and suburban areas and known by names (Maple Grove Road, Lavaque Road, Haines Road) rather than their numbers.
Township Highways / Roads
Rural township roads, maintained by the township (?), a unit of municipal government, are often gravel routes, or sometimes asphalted.