Highway

Major highways are often named and numbered by the governments that typically develop and maintain them. Australia's Highway 1 is the longest national highway in the world at over 14,500 kilometres (9,000 mi) and runs almost the entire way around the continent. China has the world's largest network of highways followed closely by the United States of America. Some highways, like the Pan-American Highway or the European routes, span multiple countries. Some major highway routes include ferry services, such as US Route 10, which crosses Lake Michigan.

Traditionally highways were used by people on foot or on horses. Later they also accommodated carriages, bicycles and eventually motor cars, facilitated by advancements in road construction. In the 1920s and 1930s, many nations began investing heavily in progressively more modern highway systems to spur commerce and bolster national defence.

Major modern highways that connect cities in populous developed and developing countries usually incorporate features intended to enhance the road's capacity, efficiency, and safety to various degrees. Such features include a reduction in the number of locations for user access, the use of dual carriageways with two or more lanes on each carriageway, and grade-separated junctions with other roads and modes of transport. These features are typically present on highways built as motorways (freeways).

Modern highway systems developed in the 20th century as the automobile gained popularity. The first United States limited access road was constructed on Long Island New York known as the Long Island Motor Parkway or the Vanderbilt Motor Parkway. It was completed in 1911.[9]

In Italy the Milano-Varese 49-kilometre-long (30 mi) autostrada was opened in 1924.

Construction of the Bonn–Cologne autobahn began in 1929 and it was opened in 1932 by the mayor of Cologne, Konrad Adenauer.[10]

In the US, the Federal Aid Highway Act of 1921 (Phipps Act) enacted a fund to create an extensive highway system. In 1922, the first blueprint for a national highway system (the Pershing Map) was published. The Federal Aid Highway Act of 1956 allocated $25 billion for the construction of the 66,000-kilometre-long (41,000 mi) Interstate Highway System over a 20-year period.[11]

In Great Britain, the Special Roads Act 1949 provided the legislative basis for roads for restricted classes of vehicles and non-standard or no speed limits applied (later mostly termed motorways but now with speed limits not exceeding 70 mph);[12] in terms of general road law this legislation overturned the usual principle that a road available to vehicular traffic was also available to horse or pedestrian traffic as is usually the only practical change when non-motorways are reclassified as special roads. The first section of motorway in the UK opened in 1958 (part of the M6 motorway) and then in 1959 the first section of the M1 motorway.[13]

Commonwealth Avenue, a major intercity highway in northeastern Manila metropolitan area, the Philippines.

Reducing travel times relative to city or town streets, modern highways with limited access and grade separation create increased opportunities for people to travel for business, trade or pleasure and also provide trade routes for goods. Modern highways reduce commute and other travel time but additional road capacity can also release latent traffic demand. If not accurately predicted at the planning stage, this extra traffic may lead to the new road becoming congested sooner than would otherwise be anticipated by considering increases in vehicle ownership. More roads allow drivers to use their cars when otherwise alternatives may have been sought, or the journey may not have been made, which can mean that a new road brings only short-term mitigation of traffic congestion.

Where highways are created through existing communities, there can be reduced community cohesion and more difficult local access. Consequently, property values have decreased in many cutoff neighborhoods, leading to decreased housing quality over time.

In transport, demand can be measured in numbers of journeys made or in total distance travelled across all journeys (e.g. passenger-kilometres for public transport or vehicle-kilometres of travel (VKT) for private transport). Supply is considered to be a measure of capacity. The price of the good (travel) is measured using the generalised cost of travel, which includes both money and time expenditure.

A taxiway crossing the Autobahn, near Leipzig

The effect of increases in supply (capacity) are of particular interest in transport economics (see induced demand), as the potential environmental consequences are significant (see externalities below).

In addition to providing benefits to their users, transport networks impose both positive and negative externalities on non-users. The consideration of these externalities—particularly the negative ones—is a part of transport economics. Positive externalities of transport networks may include the ability to provide emergency services, increases in land value and agglomeration benefits. Negative externalities are wide-ranging and may include local air pollution, noise pollution, light pollution, safety hazards, community severance and congestion. The contribution of transport systems to potentially hazardous climate change is a significant negative externality which is difficult to evaluate quantitatively, making it difficult (but not impossible) to include in transport economics-based research and analysis. Congestion is considered a negative externality by economists.[14]

A 2016 study finds that for the United States "a 10% increase in a region's stock of highways causes a 1.7% increase in regional patenting over a five-year period."[15] A 2021 study found that areas that obtained access to a new highway experienced a substantial increase in top-income taxpayers and a decline in low-income taxpayers. Highways also contributed to job and residential urban sprawl.[16]

Noise, light and air pollution are negative environmental effects highways can have on their surroundings.

Highways are extended linear sources of pollution.

Roadway noise increases with operating speed so major highways generate more noise than arterial streets. Therefore, considerable noise health effects are expected from highway systems. Noise mitigation strategies exist to reduce sound levels at nearby sensitive receptors. The idea that highway design could be influenced by acoustical engineering considerations first arose about 1973.[17][18]

Air quality issues: Highways may contribute fewer emissions than arterials carrying the same vehicle volumes. This is because high, constant-speed operation creates an emissions reduction compared to vehicular flows with stops and starts. However, concentrations of air pollutants near highways may be higher due to increased traffic volumes. Therefore, the risk of exposure to elevated levels of air pollutants from a highway may be considerable, and further magnified when highways have traffic congestion.

New highways can also cause habitat fragmentation, encourage urban sprawl and allow human intrusion into previously untouched areas, as well as (counterintuitively) increasing congestion, by increasing the number of intersections.

An aerial view of the Lakalaiva interchange in the Tampere Ring Road between the Highway 3 (E12) and Highway 9 (E63) near city of Tampere

They can also reduce the use of public transport, indirectly leading to greater pollution.

High-occupancy vehicle lanes are being added to some newer/reconstructed highways in the United States and other countries around the world to encourage carpooling and mass-transit. These lanes help reduce the number of cars on the highway and thus reduces pollution and traffic congestion by promoting the use of carpooling in order to be able to use these lanes. However, they tend to require dedicated lanes on a highway, which makes them difficult to construct in dense urban areas where they are the most effective.

To address habitat fragmentation, wildlife crossings have become increasingly popular in many countries. Wildlife crossings allow animals to safely cross human-made barriers like highways.[19]

Road traffic safety describes the safety performance of roads and streets, and methods used to reduce the harm (deaths, injuries, and property damage) on the highway system from traffic collisions. It includes the design, construction and regulation of the roads, the vehicles used on them and the training of drivers and other road-users.

A report published by the World Health Organization in 2004 estimated that some 1.2 million people were killed and 50 million injured on the roads around the world each year[20] and was the leading cause of death among children 10–19 years of age.

The report also noted that the problem was most severe in developing countries and that simple prevention measures could halve the number of deaths.[21] For reasons of clear data collection, only harm involving a road vehicle is included.[22] A person tripping with fatal consequences or dying for some unrelated reason on a public road is not included in the relevant statistics.

International sign used widely in Europe denoting the start of special restrictions for a section of highway classed as a motorway.

Russian Federal M8 highway sign.

The Cross Bronx Expressway in New York, United States uses asphalt and concrete pavement, both of which are popular road surfaces on highways.

The United States has the world's largest network of highways, including both the Interstate Highway System and the United States Numbered Highway System. At least one of these networks is present in every state and they interconnect most major cities.

China's highway network is the second most extensive in the world, with a total length of about 3,573,000 kilometres (2,220,000 mi).[23][24][25][26][27] China's expressway network is the longest Expressway system in the world, and it is quickly expanding, stretching some 85,000 kilometres (53,000 mi) at the end of 2011.[28][29] In 2008 alone, 6,433 kilometres (3,997 mi) expressways were added to the network.[30]

Longest international highway

The Pan-American Highway, which connects many countries in the Americas, is nearly 25,000 kilometres (15,500 mi) long as of 2005. The Pan-American Highway is discontinuous because there is a significant gap in it in southeastern Panama, where the rainfall is immense and the terrain is entirely unsuitable for highway construction.

Longest national highway (point to point)

The Trans-Canada Highway has one main route, a northern route through the western provinces, and several branches in the central and eastern provinces. The main route is 7,821 kilometres (4,860 mi) long as of 2006 alone, and the entire system is over 10,700 kilometres (6,600 mi) long. The TCH runs east-west across southern Canada, the populated portion of the country, and it connects many of the major urban centres along its route crossing all provinces, and reaching nearly all of their capital cities.[31] The TCH begins on the east coast in Newfoundland, traverses that island, and crosses to the mainland by ferry. It crosses the Maritime Provinces of eastern Canada with a branch route serving the province of Prince Edward Island via a ferry and bridge. After crossing the remainder of the country's mainland, the highway reaches Vancouver, British Columbia on the Pacific coast, where a ferry continues it to Vancouver Island and the provincial capital of Victoria. Numeric designation is the responsibility of the provinces, and there is no single route number across the country.

Longest national highway (circuit)

Australia's Highway 1 at over 14,500 kilometres (9,000 mi). It runs almost the entire way around the country's coastline. With the exception of the Federal Capital of Canberra, which is far inland, Highway 1 links all of Australia's capital cities, although Brisbane and Darwin are not directly connected, but rather are bypassed short distances away. Also, there is a ferry connection to the island state of Tasmania, and then a stretch of Highway 1 that links the major towns and cities of Tasmania, including Launceston and Hobart (this state's capital city).

Largest national highway system

The United States of America has approximately 6.43 million kilometres (4,000,000 mi) of highway within its borders as of 2008.[32]

Busiest highway

Highway 401 in Ontario, Canada, has volumes surpassing an average of 500,000 vehicles per day in some sections of Toronto as of 2006.[33][34]

Widest highway (maximum number of lanes)

The Katy Freeway (part of Interstate 10) in Houston, Texas, has a total of 26 lanes in some sections as of 2007.[35] However, they are divided up into general use/ frontage roads/ HOV lanes, restricting the traverse traffic flow.

Widest highway (maximum number of through lanes)

Interstate 5 along a 3.2-kilometre-long (2 mi) section between Interstate 805 and California State Route 56 in San Diego, California, which was completed in April 2007, is 22 lanes wide.[36]

Highest international highway

The Karakoram Highway, between Pakistan and China, is at an altitude of 4,693 metres (15,397 ft).;

Highest national highway

National Highway 5, in India, connecting Amritsar in Punjab with Manali in Himachal Pradesh & Leh in Ladakh, reaches an approximate altitude of 4,900 metres (16,100 ft).. The highest motorable road passes through Umling La at an altitude of 5,883 metres (19,301 ft) falls under the branch highway connecting National Highway 5 in India.[37]

Highway bus lane on Gyeongbu Expressway in South Korea.

Some countries incorporate bus lanes onto highways.

Hong Kong

In Hong Kong, some highways are set up with bus lanes to solve the traffic congestion.

District	Highway	Section
Tuen Mun	Tuen Mun Road	So Kwun Wat to Sham Tseng
Sha Tin	Lion Rock Tunnel	The entry of the tunnel

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  Gravelly Hill Interchange in Birmingham, England
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  A1 Motorway near Athens, Greece with rest area above
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  The ten-lane Highway A1 near Bologna, Italy
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  A Polish expressway in Bielsko-Biała
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  National road 5 in Kuopio, Finland
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  E4 motorway with rest area outside Nyköping, Sweden
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  Highway 401 with collector and express lanes in Mississauga, Ontario, Canada
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  Multi-lane Autobahn 9 in Munich, Germany
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  The Pan-American Highway where it serves as the main street in Máncora, Peru
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  A typical expressway in China
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  An expressway exit in Guizhou, China
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  The Tampere Highway in Vantaa, Finland
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  North Lantau Highway in Hong Kong
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  A typical expressway in India
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  32-lane toll plaza at Delhi-Gurgaon Expressway in Gurgaon, India
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  Chennai-Bangalore Highway
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  Mumbai Pune Expressway, India
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  A highway interchange in Tehran, Iran
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  The Metropolitan Expressway in Tokyo, Japan
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  A highway in Kuwait City
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  Karakoram Highway, Pakistan
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  North Luzon Expressway, the Philippines
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  Namhae Expressway in Jinju, South Korea
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  Ja-Ela Interchange in the Airport Expressway(E03) in Ja-Ela, Sri Lanka
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  3/4 highway interchange in Dubai, United Arab Emirates
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  National Route 1 near Từ Sơn, Vietnam

Look up highway in Wiktionary, the free dictionary.

Wikiquote has quotations related to Highway.

Wikimedia Commons has media related to Highways.

• Full list of Euroroutes with distances
• The Greenroads Rating System
• Legal opinion, Kansas, U.S.A.
• Proposed Trans-Global Highway
• Euroroutes with distances
• Ontario Super Highway Program (June 19, 2011)
• Video of Highway 401 through Greater Toronto