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A viaduct is a specific type of
bridge A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...
that consists of a series of arches,
pier image:Brighton Pier, Brighton, East Sussex, England-2Oct2011 (1).jpg, Seaside pleasure pier in Brighton, England. The first seaside piers were built in England in the early 19th century. A pier is a raised structure that rises above a body of ...
s or
column A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member. ...
s supporting a long elevated railway or road. Typically a viaduct connects two points of roughly equal elevation, allowing direct
overpass An overpass (called an overbridge or flyover in the United Kingdom and some other Commonwealth countries) is a bridge, road, railway or similar structure that crosses over another road or railway. An ''overpass'' and ''underpass'' together form ...
across a wide valley, road, river, or other low-lying
terrain Terrain or relief (also topographical relief) involves the vertical and horizontal dimensions of land surface. The term bathymetry is used to describe underwater relief, while hypsometry studies terrain relative to sea level. The Latin word ...
features and obstacles. The term ''viaduct'' is derived from the
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
''via'' meaning "road", and ''ducere'' meaning "to lead". It is a 19th-century derivation from an
analogy Analogy (from Greek ''analogia'', "proportion", from ''ana-'' "upon, according to" lso "against", "anew"+ ''logos'' "ratio" lso "word, speech, reckoning" is a cognitive process of transferring information or meaning from a particular subject ( ...
with
ancient Roman In modern historiography, ancient Rome refers to Roman civilisation from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD. It encompasses the Roman Kingdom (753–509 BC ...
aqueducts Aqueduct may refer to: Structures *Aqueduct (bridge), a bridge to convey water over an obstacle, such as a ravine or valley *Navigable aqueduct, or water bridge, a structure to carry navigable waterway canals over other rivers, valleys, railw ...
. Like the
Roman aqueduct The Romans constructed aqueducts throughout their Republic and later Empire, to bring water from outside sources into cities and towns. Aqueduct water supplied public baths, latrines, fountains, and private households; it also supported mining o ...
s, many early viaducts comprised a series of arches of roughly equal length.


Over land

The longest in antiquity may have been the
Pont Serme The Pont Serme or Pons Selinus, later called the Pons Septimus, was a Roman bridge of the Via Domitia in Hérault, southern France. The approximately 1500 m long viaduct crossed the wide marshes of the Orb and the Etang de Capestang west of ...
which crossed wide marshes in southern France. At its longest point, it measured 2,679 meters with a width of 22 meters. Viaducts are commonly used in many cities that are railroad hubs, such as Chicago, Birmingham, London and
Manchester Manchester () is a city in Greater Manchester, England. It had a population of 552,000 in 2021. It is bordered by the Cheshire Plain to the south, the Pennines to the north and east, and the neighbouring city of Salford to the west. The t ...
. These viaducts cross the large
railroad yard A rail yard, railway yard, railroad yard (US) or simply yard, is a series of tracks in a rail network for storing, sorting, or loading and unloading rail vehicles and locomotives. Yards have many tracks in parallel for keeping rolling stock or u ...
s that are needed for
freight train Rail freight transport is the use of railroads and trains to transport cargo as opposed to human passengers. A freight train, cargo train, or goods train is a group of freight cars (US) or goods wagons (International Union of Railways) haul ...
s there, and also cross the multi-track railroad lines that are needed for heavy rail traffic. These viaducts provide
grade separation In civil engineering (more specifically highway engineering), grade separation is a method of aligning a junction of two or more surface transport axes at different heights (grades) so that they will not disrupt the traffic flow on other tran ...
and keep highway and city street traffic from having to be continually interrupted by the train traffic. Likewise, some viaducts carry railroads over large valleys, or they carry railroads over cities with many cross-streets and avenues. Many viaducts over land connect points of similar height in a landscape, usually by bridging a river valley or other eroded opening in an otherwise flat area. Often such valleys had roads descending either side (with a small bridge over the river, where necessary) that become inadequate for the traffic load, necessitating a viaduct for "through" traffic. Such bridges also lend themselves for use by rail traffic, which requires straighter and flatter routes. Some viaducts have more than one deck, such that one deck has vehicular traffic and another deck carries rail traffic. One example of this is the
Prince Edward Viaduct The Prince Edward Viaduct System, commonly referred to as the Bloor Viaduct, is the name of a truss arch bridge system in Toronto, Ontario, Canada, connecting Bloor Street East, on the west side of the system, with Danforth Avenue on the east. The ...
in Toronto, Canada, that carries motor traffic on the top deck as
Bloor Street Bloor Street is a major east–west residential and commercial thoroughfare in Toronto, Ontario, Canada. Bloor Street runs from the Prince Edward Viaduct, which spans the Don River Valley, westward into Mississauga where it ends at Central Parkw ...
, and metro as the Bloor-Danforth subway line on the lower deck, over the steep
Don River The Don ( rus, Дон, p=don) is the fifth-longest river in Europe. Flowing from Central Russia to the Sea of Azov in Southern Russia, it is one of Russia's largest rivers and played an important role for traders from the Byzantine Empire. Its ...
valley A valley is an elongated low area often running between Hill, hills or Mountain, mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers ...
. Others were built to span settled areas, crossing over roads beneath—the reason for many viaducts in London.


Over water

Viaducts over water make use of islands or successive arches. They are often combined with other types of bridges or tunnels to cross navigable waters as viaduct sections, while less expensive to design and build than tunnels or bridges with larger spans, typically lack sufficient horizontal and vertical clearance for large ships. See the
Chesapeake Bay Bridge-Tunnel Chesapeake often refers to: *Chesapeake people, a Native American tribe also known as the Chesepian * The Chesapeake, a.k.a. Chesapeake Bay *Delmarva Peninsula, also known as the Chesapeake Peninsula Chesapeake may also refer to: Populated plac ...
. The
Millau Viaduct The Millau Viaduct (french: Viaduc de Millau, ) is a multispan cable-stayed bridge completed in 2004 across the gorge valley of the Tarn near (west of) Millau in the Aveyron department in the Occitanie Region, in Southern France. The design te ...
is a cable-stayed road-bridge that spans the valley of the river Tarn near
Millau Millau (; oc, Milhau ) is a Communes of France, commune in the Aveyron Departments of France, department in the Occitania (administrative region), Occitanie Regions of France, region in Southern France. One of two Subprefectures in France, subp ...
in southern France. It opened in 2004 and is the tallest vehicular bridge in the world, with one pier's summit at 343 metres (1,125 ft). The viaduct
Danyang–Kunshan Grand Bridge The Danyang–Kunshan Grand Bridge () is a viaduct on the Beijing–Shanghai High-Speed Railway. It is the longest bridge in the world. Bridge The bridge is located on the rail line between Shanghai and Nanjing in Jiangsu province. It is in ...
in China was the longest bridge in the world .


Land use below viaducts

Where a viaduct is built across land rather than water, the space below the arches may be used for businesses such as car parking, vehicle repairs, light industry, bars and nightclubs. In the United Kingdom, many railway lines in urban areas have been constructed on viaducts, and so the infrastructure owner
Network Rail Network Rail Limited is the owner (via its subsidiary Network Rail Infrastructure Limited, which was known as Railtrack plc before 2002) and infrastructure manager of most of the railway network in Great Britain. Network Rail is an "arm's leng ...
has an extensive property portfolio in arches under viaducts. In Berlin the space under the arches of elevated subway lines (
S-Bahn The S-Bahn is the name of hybrid urban- suburban rail systems serving a metropolitan region in German-speaking countries. Some of the larger S-Bahn systems provide service similar to rapid transit systems, while smaller ones often resemble co ...
) is used for several different purposes, including small eateries or bars.


Past and future

Elevated expressways were built in major cities such as
Boston Boston (), officially the City of Boston, is the state capital and most populous city of the Commonwealth of Massachusetts, as well as the cultural and financial center of the New England region of the United States. It is the 24th- mo ...
(
Central Artery The Central Artery (officially the John F. Fitzgerald Expressway) is a section of freeway in downtown Boston, Massachusetts; it is designated as Interstate 93, US 1 and Route 3. The original Artery, constructed in the 1950s, was named after ...
), Los Angeles, San Francisco,
Seoul Seoul (; ; ), officially known as the Seoul Special City, is the capital and largest metropolis of South Korea.Before 1972, Seoul was the ''de jure'' capital of the Democratic People's Republic of Korea (North Korea) as stated iArticle 103 ...
, Tokyo and
Toronto Toronto ( ; or ) is the capital city of the Canadian province of Ontario. With a recorded population of 2,794,356 in 2021, it is the most populous city in Canada and the fourth most populous city in North America. The city is the ancho ...
(
Gardiner Expressway The Frederick G. Gardiner Expressway, commonly known as the Gardiner Expressway or simply the Gardiner, is a partially at grade and elevated municipal expressway in Toronto, Ontario, Canada. Running close to the shore of Lake Ontario, it extends ...
). Some were demolished because they were unappealing and divided the city. In other cases, viaducts were demolished because they were structurally unsafe, such as the
Embarcadero Freeway Embarcadero, the Spanish word for wharf, may also refer specifically to: Places * Embarcadero (Oakland), California * Embarcadero (San Diego), California ** Embarcadero Circle, waterfront re-development project in San Diego * Embarcadero (San Fran ...
in San Francisco, which was damaged following an earthquake in 1989. However, in developing nations such as Thailand, India ( Delhi-Gurgaon Expressway), China, Bangladesh, Pakistan, Nicaragua elevated expressways have been built and more are under construction to improve traffic flow, particularly as a workaround of land shortage when built atop surface roads. Other uses have been found for some viaducts. In Paris, France, a repurposed rail viaduct provides a garden promenade on top and workspace for artisans below. The garden promenade is called the
Coulée verte René-Dumont The or ''Promenade plantée René-Dumont'' (French for ' of René Dumont') is a elevated linear park built on top of obsolete railway infrastructure in the 12th arrondissement of Paris, France. It was inaugurated in 1993. Description This ...
while the workspaces in the arches below are the
Viaduc des Arts The Viaduc des Arts is a converted train line located in the 12th arrondissement of Paris which is now both a string of workshops for highly skilled artisans and, on the top level, a linear park. It was, formerly, the “Viaduc de Bastille,” fo ...
. The project was inaugurated in 1993. Manhattan’s
High Line The High Line is a elevated park, elevated linear park, greenway (landscape), greenway and rail trail created on a former New York Central Railroad spur on the West Side (Manhattan), west side of Manhattan in New York City. The High Line's ...
, inaugurated in 2009, also uses an elevated train line as a linear
urban park An urban park or metropolitan park, also known as a municipal park (North America) or a public park, public open space, or municipal gardens ( UK), is a park in cities and other incorporated places that offer recreation and green space to resi ...
. In Indonesia viaducts are used for railways in
Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's List ...
and also for highways such as the
Jakarta Inner Ring Road Jakarta Inner Ring Road ( id, Jalan Tol Lingkar Dalam Jakarta), also known as the Jakarta Inner-City Toll Road ( id, Jalan Tol Dalam Kota Jakarta) is a toll road circling the city of Jakarta, Indonesia. On northern and the eastern section, the tol ...
. In January 2019 the
Alaskan Way Viaduct The Alaskan Way Viaduct ("the viaduct" for short) was an elevated freeway in Seattle, Washington, United States, that carried a section of State Route 99 (SR 99). The double-decked freeway ran north–south along the city's waterfront for , ...
in Seattle was closed and replaced with a
tunnel A tunnel is an underground passageway, dug through surrounding soil, earth or rock, and enclosed except for the entrance and exit, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube cons ...
after several decades of use due to being seismically unsafe.


See also

*
Causeway A causeway is a track, road or railway on the upper point of an embankment across "a low, or wet place, or piece of water". It can be constructed of earth, masonry, wood, or concrete. One of the earliest known wooden causeways is the Sweet Tra ...
*
Flying junction A flying junction or flyover is a railway junction at which one or more diverging or converging tracks in a multiple-track route cross other tracks on the route by bridge to avoid conflict with other train movements. A more technical term is "gr ...
*
List of bridge types Here are all types of bridges. __TOC__ {, class=wikitable ! rowspan=2, Type ! rowspan=2, Sub-type ! colspan=2, Length range ! rowspan=2, Image , - ! Longest span , -Longest total , - , Arch bridge , , , 575 meters (Ping'nan Third Bridge) ...


References

{{Authority control Bridges by structural type