Freeway

From Wikipedia, the free encyclopedia

For specific systems, such as the Autobahns of Germany, see list of highway systems with full control of access and no cross traffic. For other uses, see Freeway (disambiguation).

A freeway 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, and no railroad crossings. 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.

The word "freeway" first surfaced in the mid-1930s in proposals for the improvement of the New York City parkway network.^[1] It is currently in regular use in Canada, Taiwan, Australia, and the United States.

Contents 1 General characteristics 1.1 Access restrictions 2 Legal definitions 2.1 United States 3 Effects and controversy 4 History 4.1 Recent developments 4.1.1 Public-private partnerships in the United States 5 See also 6 References 7 Gallery of freeways around the world

[edit] General characteristics

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 sidewalk/Footpaths 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. 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.^[2] Exits are sometimes numbered to help drivers identify their desired 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^[3] or up to 18 for short distances.^[4] 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.^{[citation needed]}

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.^[5] 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 several 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 areas, there are public rest areas or service areas on freeways, as well as emergency phones on the shoulder at regular intervals.

[edit] 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 (or expressways in countries where that term is used) (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).

[edit] Legal definitions

[edit] United States

In the United States, a freeway is defined by the federal government’s Manual on Uniform Traffic Control Devices as a divided highway with full control of access.^[6] This means two things. First, adjoining property owners do not have a legal right of access, meaning that they cannot connect their lands to the highway by constructing driveways.^[7] When an existing road is converted into a freeway, all existing driveways must be removed and access to adjacent private lands must be blocked with fences or walls. Second, traffic on the highway is "free-flowing", although many non-engineers misapprehend the "free" in "freeway" to mean that such a highway must be free of charge to use. All cross-traffic (and left-turning traffic) has been relegated to overpasses or underpasses, so that there are no traffic conflicts on the main line of the highway which must be regulated by a traffic light, stop signs, or other traffic control devices. Achieving such free flow requires the construction of many bridges, tunnels, and ramp systems. The advantage of grade-separated interchanges is that freeway drivers can almost always maintain their speed at junctions since they do not need to yield to crossing traffic.

In contrast, an expressway is defined as a divided highway with partial control of access.^[8] Expressways may have driveways and at-grade intersections, though these are usually less numerous than on ordinary arterial roads.

This distinction was apparently first developed in 1949 by the Special Committee on Nomenclature of what is now the American Association of State Highway and Transportation Officials.^[9] In turn, the definitions were incorporated into AASHTO's official standards book, the Manual on Uniform Traffic Control Devices, which would become the national standards book of the U.S. Department of Transportation under a 1966 federal statute. As an official government regulation, and as a reasonable exercise of the Department's authority, the Manual carries the force of law under American administrative law. The same distinction has also been codified into the statutory law of six states: California,^[10] Mississippi,^[11] Missouri,^[12] Nebraska,^[13] Ohio,^[14] and Wisconsin.^[15]

[edit] Effects and controversy

Freeways have been constructed both between urban centers 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.^{[citation needed]}

Freeways have been heavily criticized by environmentalists and preservationists for the noise,^[16] 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.^[17][18][19]

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.^[20] 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).

Freeway opponents 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.^[21][22]

Freeway advocates argue that properly designed and maintained freeways are aesthetically pleasing, convenient, and safe, at least in comparison to the uncontrolled roads they replace or supplement, and that they expand recreation, employment and education opportunities for individuals^[23] and open new markets to small businesses.^[24] 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.^[25]

[edit] History

The 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-like road, which linked Milan to Lake Como.^[26] 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.^[27] 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.^[28]

The first long-distance rural freeway in the United States is generally considered to be the Pennsylvania Turnpike, which opened on October 1, 1940.^[29] 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.^[30] 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.^[31] And in 1942, Detroit, Michigan opened the world's first urban depressed freeway, the Davison Freeway.^[32] Meanwhile, traffic in Los Angeles continued to deteriorate and local officials began planning the huge freeway network for which the city is now famous.^[33]

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.

[edit] Recent developments

Besides the U.S., Canada, and Taiwan have adopted the term "freeway" to describe comparable roads, and they continue to extend their freeway networks. In Australia some states such as Victoria use the term freeway, and others such as New South Wales and Queensland use the term motorway.

Australia has been innovative in using the newest tunneling technologies to bring freeways into its high-density central business districts (Sydney and Melbourne). 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.

China already has the world's second largest network of freeway-like roads in terms of total kilometres and will probably overtake the U.S. well before 2025 ^{[citation needed]}.

Major progress has been made in making existing U.S. freeways and expressways more efficient. Inovations 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.

[edit] 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 designed 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.

[edit] See also

• Freeway information system
• Freeway revolts
• Hierarchy of roads
• Types of road
• List of major freeway systems
• List of roads and highways

[edit] References

v • d • e Types of road
High-speed, only access via interchanges:	Autobahn • Autocesta • Autoroute • Autopista • Autostrada • Avtocesta • Freeway • Motorway • Turnpike
High-speed, other types of access:	Expressway • Farm to Market Road • Highway • Parkway • Super two
Low speed:	Frontage road • Road • Street
Low speed low traffic:	Lane • Cul-de-sac
Other:	Dual carriageway • Toll road
Surface types:	Asphalt concrete • Brick • Cobblestone • Concrete • Gravel road • Ice road

The "Sound Tube", CityLink Tollway, Melbourne, Victoria, Australia.	Autopista Central, Santiago, Chile.	Autopista Los Libertadores, (International Freeway) Santiago, Chile	Highway 417 (The Queensway) in Ottawa, Ontario
Interstate 376 eastbound in downtown Pittsburgh, Pennsylvania	Europeway E6 E20 in southwest Sweden in Varberg	An older German Autobahn without an emergency lane	Interstate 94 entering the Lowry Hill Tunnel in Minneapolis, Minnesota
Near Kamshet 2 tunnel on the 6-lane Mumbai-Pune Expressway	The British Columbia portion of the Trans Canada Highway in Vancouver, British Columbia.	The Italian Autostrada A26 while it enters a tunnel crossing northern Apennines