Freeway

Freeways have high speed limits, multiple lanes for travel in each direction, and a large separation (either through distance or high crash barriers) between the lanes travelling in opposite directions. Crossroads are bypassed using underpasses[?] or overpasses[?], and entries and exits are limited in number and designed so as to ensure that vehicles do not disrupt the traffic as they enter or leave the freeway. Freeways do not usually have traffic lights.

In the United States, many freeways are part of the Interstate highway system, which superseded the largely at-grade United States highway system (though most of the latter highways are still in use). The first national freeway system was the German Autobahn. 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. On December 30, 1940 California opened its first freeway, the Arroyo Seco Parkway[?], now called the Pasadena Freeway, which connected Pasadena with Los Angeles.

The term has different definitions at different places even within the same country. In California, USA, roads called 'expressways' can have crossroads and traffic lights at intersections, but freeways do not have any at-grade crossroads at all, and the only traffic lights are those at toll booths and ramp meters that control the flow of merging traffic. However, freeways should be distinguished from toll roads (or turnpikes), for which there is a fee for use, and which historically (before the advent of electronic toll collection[?]) required users to stop to pay tolls. People in the northeastern USA, unlike those in most of the country, do not use the word "freeway" except perhaps when speaking of highways in other parts of the country. The word "freeway" is also generally used in Australia.

Freeways have been constructed both between urban centres and within them, making practical the style of suburban development found near most modern cities. As well as reducing travel times, the ease of driving on them reduces accident rates.

Freeways come under heavy criticism from environmentalists, who argue that freeway expansion is self-defeating - the induced demand[?] hypothesis. By encouraging development many kilometres away from jobs and services, freeways contribute to increasing traffic flows, and thus the freeway ends up just as congested as previously, thus requiring the freeway to be widened. (However the fact that there is additional travel indicates that it is adding value to those users). They also take up a great deal of room, often through remaining undeveloped patches of cities, and by encouraging driving contribute to both urban pollution and the greenhouse effect. Critics of this view contend that new traffic will grow anyway, whether or not freeways are expanded. And thus, without widening, traffic would be even worse than it is, contributing even more pollution.

See also

• List of roads and highways
• Autobahn
• Parkway