Freeway

Categories: Road infrastructure | Road transport

For other uses, see Freeway (disambiguation).

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.

Gallery of design features

Signage for entering the freeway

American "begin freeway" sign

American on-ramp sign

European on-ramp and "begin freeway" sign

Signage for leaving the freeway

American "End Freeway" warning sign

American numbered exit off-ramp sign

French end of freeway/off-ramp sign

Signage for finding one's way

American guide signs	American numbered exit guide sign	Canadian guide signs	Chinese guide signs
Malaysian guide signs	Swiss guide signs	Chilean guide signs	Saudi Arabian guide signs

Grade separations

American freeway overpass

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).

Ancillary facilities

In most parts of the world, there are public rest areas on freeways and expressways as well as other types of highways. In some U.S. states, public rest areas are located almost exclusively on freeways or expressways (since only those routes carry the high traffic necessary to justify the area's maintenance cost).

Nomenclature

Worldwide

Freeway is the term used in most of the United States, parts of Canada, and parts of Australia, notably Victoria, South Australia and Western Australia; the United Kingdom, Republic of Ireland, the rest of Australia and other Commonwealth countries prefer motorway, most of Canada uses expressway, while the province of Québec uses Autoroute; Autoroute is also used in France and other francophone countries; Mexico and other Spanish-speaking countries use the term Autopista; the German-speaking world uses Autobahn, the Dutch-speaking world uses autosnelweg, Italy, Poland and Romania use autostrada; and China and Japan use the term expressway, although they once used freeway. Croatia uses Autocesta.

Some RIRO expressways may have at-grade intersections. Some commentators consider them to be freeways because they have design speeds of 65 mph or higher. However, others argue that RIRO expressways lack complete-controlled access since existing private businesses are allowed to retain their entrances and thus should not be classified as full/true freeways.

United States

The United States definition, as accepted by civil engineers, is that an expressway is any highway to which adjoining property owners do not have a legal right of access. A freeway is an expressway which is free-flowing; that is to say, there are no traffic conflicts on the main line of the highway which must be mediated by a traffic signal, stop signs, or related traffic controls. Another way to look at it is that an expressway is limited-access, and a freeway is controlled-access, but this distinction is not universally accepted. Many non-engineers misapprehend the "free" in "freeway" to mean that such a highway must be free of charge to use. In some states, like California, the vast majority of freeways are toll-free (except where they cross an occasional toll bridge), while other states like Illinois and Florida have toll plazas at every exit on certain expressways.

In the U.S., the terms expressway and freeway are legally defined by federal regulation and under the laws of most states according to civil engineering usage described above. However, the distinction between these two terms is not universal, and in several states which built freeways very early on (including Connecticut, Illinois, Massachusetts, New Jersey, New York, and Pennsylvania), the terms expressway and freeway have the same meaning, and usually expressway or just highway, an older usage, is preferred. In New Jersey and Pennsylvania, newer roads are often officially styled freeways, where older roads retain the title expressway. These are also states which have toll roads, and therefore the distinction is made between a tollway (or turnpike) and a freeway, the latter not costing toll. According to people from these states, an "expressway" is the general category, and then, depending on whether the expressway is toll or free, it may be either a tollway or a freeway. Frequently, in the Midwest and the South, neither "freeway" nor "expressway" is commonly used, and the preferred term is "interstate," even in cases where the expressway might not have been designated an Interstate Highway.

In the rest of the country, freeway is the usual term; however, the distinction between freeways and expressways is not always as clear or well-understood as it is in California, which has many of both kinds of highway.

Florida has different definitions for both "expressway" and "freeway" than other states. In Florida, an "expressway" is defined as a limited-access toll road, while a "freeway" is any other limited- or controlled-access road which costs no money to travel on.

Canada

In Ontario, while the definitions of "freeway" and "expressway" are consistent with that of the US, "highway" is used far more often than freeway, especially inside the Greater Toronto Area. While this has caused some confusion because the province applies "highway" (The King's Highway) to principal roads in its network, whether freeway or non-freeway, it is usually resolved simply by using the 400-series number to distinguish the freeway. Nonetheless, outside of the GTA, the 400-series numbering does not entirely solve the problem as there are non 400-series freeways built to similar standards such as the Conestoga Parkway (which includes sections of Highways 7, 8 and 85, including a long 7/8 multiplex). The only freeway officially labelled as such is the Macdonald-Cartier Freeway but it is usually known as Highway 401 or "the 401".

In Toronto, Ontario, several roads labelled "expressways" in the municipal network are actually fully controlled-access freeways such as the Gardiner Expressway and Spadina Expressway (later renamed Allen Road).

Other provinces use varying rules in their official road designations.

Alberta and British Columbia have spent 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.

Construction issues

Freeways have been constructed both between urban centres and within them, making common the style of sprawling suburban development found near most modern cities. As well as reducing travel times, the ease of driving on them reduces accident rates, though the speeds involved also tend to increase the severity and death rate of the collisions (or crashes) that do still happen.

Frontage roads

Because abutters do not have the right of access that they would have for an ordinary public road, the authority undertaking construction of a freeway is frequently required to provide alternate means of access to those landowners. This is frequently accomplished, in areas lacking a dense surface street network, by construction of two uncontrolled roads parallel to and on either side of the freeway, known as frontage roads. These often are designed with one-way traffic flow, but not always.

In Texas, where this pattern is perhaps at its zenith, such roads are frequently constructed in anticipation of a future freeway corridor, as many as ten years in advance, in order to influence development patterns on the adjoining land. Frontage roads are also often constructed in more densely-developed areas as a means to provide convenient direct access to and from the parallel freeway while minimizing the need for interchanges at every major cross street. However, some traffic studies have indicated that this particular type of access and the development that ensues generally causes significant traffic congestion and disrupts flows along major freeways. These studies prompted concern for TxDOT, which formally adopted a major shift in frontage road policy (2002) by stating that no new frontage roads will be built along any proposed limited-access freeways, thus ending a long-standing pattern of freeway-induced development in Texas. Access issues will continue to be assessed on a local basis, and frontage roads could still be constructed if warranted by traffic studies.

Collector lanes

The successor to frontage/service roads in urban freeways is the collector-express system; the lanes accessing (often closely-spaced) interchange ramps are known as collector/distributor roads. Newer suburban freeways are designed with interchanges spaced far apart such that neither service roads or collector lanes are needed.

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.

Controversy

Freeways have been heavily criticized by environmentalists and preservationists for the noise, pollution, and economic shifts they bring. Additionally, they have also been criticized by the driving public for the inefficiency with which they handle peak hour traffic^[7][8].

Often, rural freeways open up vast areas to economic development, generally raising property values. But mature freeways in urban areas are quite often a source of lowered property values, contributing to the deleterious effects of urban blight. One major problem is that even with overpasses and underpasses, freeways tend to divide neighborhoods — especially impoverished ones where residents are less likely to own a car that could easily take them around the freeway^[9].

For these reasons, almost no new urban freeways have been built in the U.S. since 1970. Some have even been demolished and reclaimed as boulevards, notably in San Francisco (Embarcadero Freeway) and Milwaukee (Park East Freeway).

Some argue that freeway expansion is self-defeating, in that expansion will just generate more traffic. That is, even if traffic congestion is initially shifted from local streets to a new or widened freeway, people will begin to run errands and commutes to more remote locations which took too long to reach in the past. Over time, the freeway and its environs will become congested again as both the average number and distance of trips increase. This is the debated induced demand hypothesis^[10][11].

Pro-freeway advocates point out that properly designed and maintained freeways are aesthetically pleasing, convenient, and safe, at least in comparison to the uncontrolled roads they replace or supplement. Freeways expand recreation, employment and education opportunities for individuals^[12] and open new markets to small businesses. And for many, uncongested freeways are fun to drive. Another common argument is that public transit has often failed to relieve traffic congestion, due to the current trend of increasing private car ownership as family wealth levels increase. Public transit projects are just as costly as building freeways, and may constitute an inefficient use of public funds that could have been used more effectively for acquiring right-of-way and building more freeways.

Finally, constructing new freeways in built-up urban areas could divert cars away from local city streets, and in turn might make communities safer. The closure of an existing urban freeway (or the imposition of tolls) could simply force traffic back onto local streets, instead of making it disappear. However, some studies [13] have shown that the removal of urban freeways actually reduce traffic congestion by causing people to find alternate routes, use mass transit or simply reduce driving altogether.

At present, freeway expansion has largely stalled in the United States, due to a multitude of factors that converged in the 1970s: higher due process requirements prior to taking of private property, increasing land values, increasing costs for construction materials, local opposition to new freeways in urban cores, the passage of the National Environmental Policy Act (which imposed the requirement that each new project must have an environmental impact statement or report), and falling gas tax revenues as a result of the nature of the flat-cent tax (it is not automatically adjusted for inflation) and the tax revolt movement^[14]. Dramatic improvements in vehicle gas mileage have also reduced gas tax revenues.

Recent developments

Outside the U.S., many countries continue to rapidly expand their freeway networks. Examples include: Australia, Canada, Chile, China, France, India, Israel, Mexico, Malaysia and Taiwan. Australia and France in particular have been innovative in using the newest tunneling technologies to bring freeways into high-density downtowns (Sydney and Melbourne) and historic rural areas (Versailles). China already has the world's second largest freeway network in terms of total kilometers and will probably overtake the U.S. well before the end of the 21st century.

In Australia, the city of Adelaide pioneered the concept of a dedicated reversible freeway. The M2 expressway runs toward the city in the morning and out of the city in the evening. Its ramps are designed so that they can double as on- or off-ramps, depending upon the time of day. Gates and electronic signage prevent motorists from driving in the wrong direction.

Meanwhile, major progress has been made in making existing U.S. freeways and expressways more efficient. Experiments include the addition of high-occupancy vehicle lanes (HOV lanes) to discourage driving solo, and building new roads with train tracks down the median (or overhead). California's Caltrans has been very innovative in squeezing HOVs into limited right-of-way (by elevating them), and in building special HOV-only ramps so that HOVs can switch freeways or exit the freeway without having to merge across regular traffic. Many states have added truck-only ramps or lanes on heavily congested routes, so that cars need not weave around slow-moving big rigs.

Intelligent transportation systems (ITS) are also increasingly used, with cameras to monitor and direct traffic, so that police, fire, ambulance, tow, or other assistance vehicles can be dispatched as soon as there is a problem, and to warn drivers via variable message signs, radio, television, and the web to avoid problem areas. Research has been underway for many years on how to partly automate cars by making smart roads with such things as buried magnets to guide sensor-equipped vehicles, with on-board GPS to determine location, direction, and destination. While these systems may eventually be used on surface streets as well, they are most practical in a freeway setting.

In the United States, a few short privatized tolled freeways have also been built by private companies with mixed success.

Freeways around the world

Interstate 405 in Irvine, California, with an interchange in the foreground

The "Sound Tube", CityLink Freeway, Melbourne, Victoria, Australia.

Autopista Central, Santiago, Chile.

Autopista Los Libertadores, (International Freeway) Santiago, Chile

References

^  Anonymous. "Median barriers prove their worth." Public Works 123, no. 3 (March 1992): 72-73.

^  Bernstein, Victor H. "Safer Motor Roads: New Construction Principles Introduced On Modern Highways To Cut Accidents." New York Times, 1 December 1935, p. 21.

^  Cervero, Robert. "Road expansion, urban growth, and induced travel: a path analysis." Journal of the American Planning Association 69, no. 2 (Spring 2003): 145-164.

^  Coulombe, Gerard. "Doing The Turnpike Crawl." New York Times, 6 July 1986, sec. CN, p. 16.

^  Hill, Gladwin. "Traffic Chaos Spurs Los Angeles To Plan 'Freeways' On Mass Scale: Coast Metropolis, Lacking Rapid Transit System Such as New York Possesses, Maps $300,000,000 Highway Set-Up." New York Times, 13 January 1947, p. 12.

^  Martin, Hugo. "Will More Freeways Bring More Traffic?" Los Angeles Times, 10 April 2002, sec. B, p. 1.

^  McCreery, Sandy. "Don't just sit there, enjoy it!" New Statesman, 23 July 2001, 23.

^  Patton, Phil. "A quick way from here to there was also a frolic." Smithsonian 21, no. 7 (October 1990): 96-108.

^  Spivak, Jeffrey. "Today's road opening represents progress, pain." Kansas City Star, 27 July 1999, sec. A, p. 1.

^  Taylor, Brian D. "Public perceptions, fiscal realities, and freeway planning: the California case." Journal of the American Planning Association 61, no. 1 (Winter 1995): 43-59.

^  Van Hengel, Drusilla, Joseph DiMento, and Sherry Ryan. "Equal Access? Travel Behaviour Change in the Century Freeway Corridor, Los Angeles." Urban Studies 36, no. 1 (March 1999): 547.

^  Yordan, E.L. "The 'Freeway' System Expands: Broader Roads With Grade Crossings Eliminated Are Built And Latest Designs Envision Still Greater Speed And Safety." New York Times, 24 February 1935, p. 21.

See also

• Motorway, Autobahn, Autoroute, Expressway
• Divided highway
• Hierarchy of roads
• Highway
• Non-motorized vehicle access on freeways
• List of roads and highways
• Parkway
• Road safety
• List of major freeway systems
• Controlled-access highway
• Limited-access highway
• Freeway revolts

External links

• Georgia NaviGAtor - example of a freeway information system
• A new concept in motorway design - Rethink the highways

ca:Autopista da:Motorvej de:Autobahn es:Autovía fr:Autoroute ja:高速道路 it:Autostrada nl:Autosnelweg pl:Autostrada sv:Motorväg

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