Freeway
A freeway (also superhighway, expressway or motorway as further explained below) is a multi-lane highway (road) designed for high-speed travel by large numbers of vehicles, and having no traffic lights, stop signs, nor other regulations requiring vehicles to stop for cross-traffic.
In general
Design features
Freeways have high speed limits and multiple lanes for travel in each
direction. The number of lanes may vary from four or six in rural areas
to as high as sixteen or eighteen in certain global cities.
A median (originally "medial strip"[1]) or central reservation
separates the lanes travelling in opposite directions. Separation may
be achieved through distance or through the use of high crash barriers
like cable barriers and Jersey barriers[2].
Crossroads are bypassed by grade (height) separation using underpasses
and overpasses. In addition to the sidewalks attached to roads that go
over or under a freeway, most countries also provide specialized pedestrian
bridges and underground tunnels. Such structures enable pedestrians and
cyclists to cross the freeway without having to make a long detour to
the nearest road for which a grade separation has been provided.
Freeway entrances and exits are limited in number, and are designed with
special onramps and offramps, so as to ensure that vehicles do not disrupt
the main flow of traffic as they enter or leave the freeway. In some countries,
the exits are numbered. Exit numbering may be by mile or kilometre, or
in a simple sequential fashion.
Where freeways cross, engineers provide interchanges with elaborate ramp
systems that allow for smooth, uninterrupted transitions between all through
routes (as funds permit).
Because the high speeds reduce decision time, freeways usually have more
traffic signs than the equivalent signs on most highways and roads; the
signs are often also larger. In major cities, especially on freeways six
lanes in width or wider, guide signs are mounted on overpasses or overhead
gantries so that drivers can see where each lane goes.
Some countries prefer to use a special icon for freeways, while others
simply post "Freeway Entrance" and "Begin Freeway"
signs.
Another common problem with freeways is that it is nearly impossible to
avoid wrong-way drivers, and the subsequent head-on collisions are often
fatal. Therefore, special signage and lane markings are used to discourage
drivers from going the wrong way.
Freeways do not usually have traffic lights, but expressways may, in places
where this distinction is made.
Measures to prevent wrong way drivers
Used by some U.S. states at freeway ends and off-ramps
Access restrictions
To minimize accidents, access to freeways is usually limited to vehicles
capable of consistently maintaining a high speed, like automobiles, trucks,
motorcycles, vans, and buses. Pedestrians, bicyclists, slow-moving vehicles,
horses, horse-drawn vehicles, and anything else that might obstruct fast-moving
vehicles are all prohibited; however some freeways allow non-motor vehicles
(e.g., bicycles) (see non-motorized vehicle access on freeways for more
info).
nt millions of dollars investing to make highways into freeways. In Alberta,
the main freeway is Alberta Highway 2 running between Edmonton and Calgary.
The road just recently became a freeway all through the city of Calgary.
Edmonton, however, has many interchanges in progress. On the Trans-Canada
Highway east of Calgary, it is a freeway up until the town of Lake Louise.
In British Columbia however, freeways are very abundant in the city of
Vancouver. Highway 99(which south is the Interstate 5) runs from the border
of the USA to Whistler. The Trans-Canada Highway is also a freeway from
Hope right on until Horseshoe Bay.
History
The concept of limited-access automobile highways dates back to the New
York City area Parkway system, which began to be constructed in 1907–1908.
Designers elsewhere also researched these ideas, especially in Germany,
where the Autobahn became the first national freeway system.
The term "freeway" first surfaced in the mid-1930s in proposals for the improvement of the New York City parkway network[3][4]. However, the first true freeway in the United States is generally considered to be the Pennsylvania Turnpike, which opened on October 1, 1940. The Turnpike was so advanced for its time that tourists even had picnics in the median (that is, after it was already open to traffic) and local entrepreneurs did a brisk business in souvenirs[5]. It was designed so that straightaways could handle maximum speeds of 102 miles per hour, and curves could be taken as fast as 90.
Shortly thereafter, on December 30, 1940, California opened its first freeway, the Arroyo Seco Parkway (now called the Pasadena Freeway) which connected Pasadena with Los Angeles. And in 1944, Michigan opened its first freeway, the Davison Freeway, within Detroit. Meanwhile, traffic in Los Angeles continued to deteriorate and local officials began planning the huge freeway network for which the city is now famous[6].
Today, many freeways in the United States belong to the extensive Interstate
highway system (most of which was completed between 1960 and 1990). Almost
all interstates are freeways, but the earlier United States highway system
and the highway systems of U.S. states also have many sections that are
limited-access (though these systems are mostly composed of uncontrolled
roads). Only a handful of sections of the Interstate system are not freeways,
such as I-81 as it crosses the American span of the 2-lane Thousand Islands
Bridge.
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