Freeway
For other meanings of freeway, see freeway (disambiguation). For specific systems, such as the Autobahns of Germany, see list of highway systems with full control of access and no cross traffic. |
This stylized drawing of an overpass is used to represent a freeway in many countries. |
A
freeway (also
motorway or
expressway) is a type of
highway that is designed for safer high-speed operation of
motor vehicles through the elimination of
at-grade intersections. This is accomplished by imposing full control of access from adjacent properties and eliminating all
cross traffic with
grade separations and
interchanges. Such highways are usually
divided with at least two
lanes in each direction. Because traffic never crosses at-grade, there are generally no
traffic lights or
stop signs. A freeway is also used to describe a highway without tolls
[dictionary.reference.com/browse/freeway A highway without tolls.][www.m-w.com/dictionary/freeway a toll-free highway.][encarta.msn.com/dictionary toll-free road: a highway that can be used without paying a toll.].
Note:
Expressway has other meanings, and
motorway typically applies only to those roads designated as motorways by the national highway agency. Thus this article will primarily use the term freeway for clarity and conciseness. The terms
controlled access and
limited access are also used, but both terms can also apply to
arterial roads with partial control of access or even city streets to which the city restricts
curb cuts.
Despite the name, a freeway can be a
toll road.
[Florida's Turnpike and Toll Road Numbering and Signing Program: "To identify a toll facility at a freeway to freeway interchange, both the advance guide sign and exit direction guide sign shall use the 36 x 48-inch toll route shield."]Freeways, by definition, have no cross traffic in the form of other roads,
railroads or
multi-use trails. Elimination of cross traffic is typically achieved with grade separation using
underpasses and
overpasses. In addition to
sidewalks attached to roads that cross a freeway, specialized pedestrian bridges or tunnels may also be provided. These structures enable
pedestrians and
cyclists to cross the freeway without a long detour to the nearest motor vehicle crossing.
Movable bridges are occasionally present on freeways, requiring drivers to yield to river traffic.
Access is typically provided only at interchanges, though lower-standard
right-in/right-out access can be used for direct connections to side roads or
driveways to adjacent property. In ideal cases, sophisticated interchanges allow for smooth, uninterrupted transitions between intersecting freeways. However, sometimes it is necessary to exit onto a surface road to transfer from one freeway to another.
[Breezewood, Pennsylvania is a good example in the U.S.] Exits are sometimes
numbered to help drivers identify their exit.
Two-lane freeways, often undivided, are sometimes built when traffic volumes are low or right-of-way is limited; they may be designed for easy conversion to one side of a four-lane freeway. Otherwise, freeways typically have at least two lanes in each direction; some busy ones can have as many as 16 lanes
[Portions of the Downtown Connector in Atlanta, Georgia has eight lanes in each direction.] or up to 18 for short distances.
[In Mississauga, Ontario, Highway 401 uses collector-express lanes for a total of 18 lanes through its intersection with 403/410 and 427.] These wide freeways may use separate
collector and express lanes to separate through traffic from local traffic, or special
high-occupancy vehicle lanes, either as a special restriction on the innermost lane or a separate roadway, to encourage
carpooling. These HOV lanes, or roadways open to all traffic, can be
reversible lanes, providing more capacity in the direction of heavy traffic, and reversing direction before traffic switches. Sometimes a
collector/distributor road, a shorter version of a local lane, shifts weaving between closely-spaced interchanges to a separate roadway or altogether eliminates it.
Freeways can have
frontage roads, normal surface roads parallel to and on either side of the freeway, to provide access to adjacent properties. Frontage roads typically have
one-way traffic flow in
urban areas and two-way traffic flow in
rural areas.
Except on some
two-lane freeways (and very rarely on wider freeways), a
median separates the opposite directions of traffic. This strip may be as simple as a grassy area, or may include a
crash barrier such as a
Jersey barrier to prevent
head-on collisions.
[Anonymous, "Median barriers prove their worth", Public Works 123, no. 3 (March 1992): 72-73.] On some freeways, the two carriageways are built on different alignments; this may be done to make use of available corridors in a mountainous area or to provide narrower corridors through dense
urban areas.
Speed limits are generally higher than on similar non-freeways, and are sometimes nonexistent (for instance on some
German Autobahns). Because the high speeds reduce decision time, freeways are usually equipped with a larger number of
guide signs than other roads, and the signs themselves are physically larger. In major cities, guide signs are often mounted on overpasses or overhead gantries so that drivers can see where each lane goes.
In most parts of the world, there are public
rest areas or
service areas on freeways. Many countries also provide
emergency phones alongside freeways at regular intervals.
Freeways with at-grade intersections
Many rural secondary (non-Interstate designated) freeways such as in
Ohio may have some at-grade intersections where traffic on the crossing roads yields or stops; but the freeway dosen't, there is also a mix of grade-separated overpasses at major ramp junctions with roads that would otherwise form a traffic light junction with the lower-standard freeway. Examples include
U.S. Route 23 (including
Ohio state highway 15 between
Interstate 75 and
Delaware, Ohio where it becomes an expressway with traffic lights east of the city limits. These special freeways sometimes have speed limits as high as 65 or 70 MPH. These types of freeways are often a financial compromise.
Interstate highways however, have some instances of at-grade intersections in the western United States. However, many of the at-grade intersections there are often of
dirt roads and some of them are T-junctions on only one direction of the freeway.
Access restrictions
To reduce the probability that high-speed freeway traffic will have to slow down for slower same-direction traffic, access to freeways is usually limited to classes of
motor vehicles that are powerful enough to maintain a certain minimum speed. Some
East Asian countries partially restrict the use of motorcycles or ban them completely from freeways (see
restrictions on motorcycle use on freeways).
In many areas, travelers using low-powered modes of transportation (such as
pedestrians,
bicyclists,
equestrians, and
moped drivers) are banned at all times from freeways by default. These users are allowed on freeways in some jurisdictions, usually where freeways too often replaced (rather than supplemented) existing roads (see
non-motorized vehicle access on freeways).
Special classification
In many countries, a national network of freeways has special status with respect to funding, signage, construction standards or access. For instance,
motorways in the
United Kingdom are the only roads from which slow vehicles can be banned,
[The Highway Code, section 227] and are assigned labels beginning with M and special blue signs. Normal highways (
A roads) built to freeway standards are open to all traffic and use green signs.
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 that do still happen.
Freeways have been heavily criticized by environmentalists and preservationists for the noise,
[Hugo Martin, "Sounding Off On Noise: Freeways' Neighbors Struggle To Drown Out Road Racket, Experts Say The Din Creates Mental And Physical Hazards", Los Angeles Times, 20 April 2003, B1.] 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.
[Sandy McCreery, "Don't just sit there, enjoy it!" New Statesman, 23 July 2001, 23.][Martha Smilgis, "Trapped behind the wheel; clever commuters learn to live in the slow lane", Time, 20 July 1987, p. 64-65.][Gerard Coulombe, "Doing The Turnpike Crawl", New York Times, 6 July 1986, sec. CN, p. 16.]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.
[Jeffrey Spivak, "Today's road opening represents progress, pain", Kansas City Star, 27 July 1999, sec. A, p. 1.] 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
Portland (
Harbor Drive),
San Francisco (
Embarcadero Freeway) and
Milwaukee (
Park East Freeway). Growing anti-urban freeway sentiment has resulted in some significant policy changes; the most noteworthy was an FHWA case study
[Case Study: "Route 9 [sic Reconstruction", Federal Highway Administration]] involving the
West Side Highway in Manhattan, a quintessential urban freeway in need of expansion and reconstruction. The outcome of the study basically concluded that the current elevated highway should be replaced with a new, at-grade boulevard with integrated pedestrian facilities. This case study may be a precedent for areas where a typical, elevated urban freeway is not desirable and/or may not be effective at handling impacted traffic. In
Boston, Massachusetts, the elevated
Central Artery, originally built in the 1950s, was demolished in 2005 when new tunnels were built for an expanded Central Artery directly beneath the pre-existing elevated highway. Completion of the project, referred to as the
Big Dig allowed Boston to reunite its business district with the waterfront, severed by the original elevated Central Artery, while maintaining the expressway through downtown, now located underground.
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 controversial idea is known as the
induced demand hypothesis.
[Robert Cervero, "Road expansion, urban growth, and induced travel: a path analysis", Journal of the American Planning Association 69, no. 2 (Spring 2003): 145-164.][Hugo Martin, "Will More Freeways Bring More Traffic?" Los Angeles Times, 10 April 2002, sec. B, p. 1. ] 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
[Drusilla Van Hengel, 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.] and open new markets to
small businesses.
[Christy Borth, Mankind on the Move: The Story of Highways (Washington, D.C.: The Automobile Safety Foundation, 1969), 248 and 264.] And for many, uncongested freeways are fun to drive.
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.
[Brian D. Taylor, "Public perceptions, fiscal realities, and freeway planning: the California case", Journal of the American Planning Association 61, no. 1 (Winter 1995): 43-59.]Image:TullamarineFwy.jpg|The "Sound Tube", CityLink Freeway, Melbourne, Victoria, Australia.Image:Autopista-Central-2.jpg|Autopista Central, Santiago, Chile.Image:AutopistaLibertadores.JPG|Autopista Los Libertadores, (International Freeway) Santiago, ChileImage:Queensway east of Riverside Drive Ottawa.jpg|Highway 417 (The Queensway) in Ottawa, OntarioImage:376 east.jpg|Interstate 376 eastbound in downtown Pittsburgh, Pennsylvania
Image:Motorvag - bild.jpg|Europeway E6 E20 in southwest Sweden in VarbergImage:Old_Autobahn_DE.jpg|An older German Autobahn without an emergency laneImage:Lowry_Hill_Tunnel.jpg|Interstate 94 entering the Lowry Hill Tunnel in Minneapolis, MinnesotaThe concept of limited-access automobile highways dates back to the
New York City area
Parkway system, whose construction began in
1907–
1908; but parkways are traditionally distinguished from freeways by lower design speeds and a ban on commercial traffic. Designers elsewhere also researched similar ideas, especially in
Germany, where the
Autobahn would become the first national freeway system.
However, in 1925,
Italy was technically the first country to build a freeway, which linked
Milan to
Lake Como.
[Paul Hofmann, "Taking to the Highway in Italy", New York Times, 26 April 1987, 23.] It is known in Italy as the Autostrada dei Laghi.
Meanwhile, in
England, the related concept of the motorway was first proposed by Sidney Webb in a 1910 book,
The King's Highway, but was not formally embraced by the government until the passage of the
Special Roads Act 1949.
[Geoffrey Hindley, A History of Roads (London: Peter Davies, 1971), 142.] In 1926, the English intellectual
Hilaire Belloc recognized the necessity of grade-separated roads for "rapid and heavy traffic", but thought they would be the exception rather than the rule:
The creation of a great network of local highways suitable for rapid and heavy traffic is impossible. Even if the wealth of the community increases, the thing would be impossible, because it would mean the destruction of such a proportion of buildings as would dislocate all social life.
[Hilaire Belloc, The Highway and Its Vehicles (London: The Studio Limited, 1926), 39.]The word "freeway" first surfaced in the mid-1930s in proposals for the improvement of the New York City parkway network.
[E.L. Yordan, "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.] The first long-distance rural freeway in the United States is generally considered to be the
Pennsylvania Turnpike, which opened on
October 1,
1940.
[Phil Patton, The Open Road: A Celebration of the American Highway (New York: Simon & Schuster, 1986), 77.] 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.
[Phil Patton, "A quick way from here to there was also a frolic", Smithsonian 21, no. 7 (October 1990): 96-108.] 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.
[Cecilia Rasmussen, "Behind the Wheel: Harrowing Drive on State's Oldest Freeway — Curvy, quirky 110 carries motorists between downtown Los Angeles and Pasadena", Los Angeles Times, 6 November 2001, 2.] And in 1942,
Detroit, Michigan opened the world's first urban depressed freeway, the
Davison Freeway.
[http://www.autolife.umd.umich.edu/Environment/E_Casestudy/Davison.htm] Meanwhile, traffic in Los Angeles continued to deteriorate and local officials began planning the huge freeway network for which the city is now famous.
[Gladwin Hill, "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.]Today, many freeways in the United States belong to the extensive
Interstate highway system (most of which was completed between 1960 and 1990). Nearly all Interstate highways are freeways. The earlier
United States highway system and the highway systems of
U.S. states also have many sections that are built to controlled-access standards (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 and a segment of
Interstate 93 through
Franconia Notch,
New Hampshire that is a 2-lane road with partial access control.
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,
Pakistan, the
Philippines,
Spain 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 2025.
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.
Public-private partnerships in the United States
Until the late 1990s, funding of construction and maintenance of the Interstate Highway System was by the national gasoline tax. Additionally, the original
Highway Act of 1956 prohibited states from collecting tolls on Interstate-funded expressways. As more miles of expressways were completed, the cost of maintaining the infrastructure increased dramatically. A major issue that has slowed new expressway constructing in America has been the application of highway funds to maintaining and repairing existing infrastructure. Most of the expressways in America are near or have exceeded their deisgned life span, which necessitates replacing of bridges and overpasses and reconstruction of the driving surfaces on many expressways nationwide.
To address the issue of lack of funding for new expressways and maintenance of existing roads, legislation enacted in 1998 gives states greater flexibility in funding major highway projects. Specifically the legislation, known as TEA-21 in official documents, authorizes states to add tolls to Interstate-funded expressways. Additionally, it gave states the latitude to enter into public-private partnership
P3 arrangements to facilitate expansion and maintenance of the expressway network.
Texas,
Florida, and
California quickly took advantage of the TEA-21 legislation and began on massive projects to expand their respective states' expressway networks, complementing existing interstate expressways with privately funded and operated toll expressways. In 2004 and 2005,
Illinois and
Indiana joined the club of states looking to private sector investment for expanding and maintaining expressways. Meanwhile in
New York and
Massachusetts, the respective state public authorities that operate the
New York State Thruway and
Massachusetts Turnpike have generated enough revenue to assume maintenance of other expressways beyond the roads on which tolls are collected. The
Massachusetts Turnpike Authority provided more than 50 percent of the funding to complete the
Big Dig project in Boston, and later assumed responsibility for operating the Central Artery, the
Sumner Tunnel, and the
Callahan Tunnel following the project's completion in 2005.
As federal funding dries up for expanding and maintaing America's expressway network, states are looking to innovative solutions using a combination of state and federal funding, toll collection through public authorities, and private sector investment.
In the United States, a few short privatized
tolled freeways have also been built by private companies with mixed success.
*
Freeway information system*
Freeway revolts*
Hierarchy of roads*
Types of road*
List of major freeway systems*
List of roads and highways
