An overpass, called an overbridge or flyover (for a road only) in the United Kingdom and some other

Commonwealth A commonwealth is a traditional English term for a political community founded for the common good. The noun "commonwealth", meaning "public welfare, general good or advantage", dates from the 15th century. Originally a phrase (the common-wealth ...

countries, is a

bridge A bridge is a structure built to Span (engineering), span a physical obstacle (such as a body of water, valley, road, or railway) without blocking the path underneath. It is constructed for the purpose of providing passage over the obstacle, whi ...

road A road is a thoroughfare used primarily for movement of traffic. Roads differ from streets, whose primary use is local access. They also differ from stroads, which combine the features of streets and roads. Most modern roads are paved. Th ...

railway Rail transport (also known as train transport) is a means of transport using wheeled vehicles running in railway track, tracks, which usually consist of two parallel steel railway track, rails. Rail transport is one of the two primary means of ...

or similar structure that is over another road or railway. An ''overpass'' and ''

underpass A subway, also known as an underpass, is a grade-separated pedestrian crossing running underneath a road or railway in order to entirely separate pedestrians and cyclists from motor or train traffic. Terminology In the United States, as ...

'' together form a

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 tr ...

Stack interchange A directional interchange, colloquially known as a stack interchange, is a type of grade-separated junction between two controlled-access highways that allows for free-flowing movement to and from all directions of traffic. These interchanges e ...

s are made up of several overpasses.

History

The world's first railroad flyover was constructed in 1843 by the

London and Croydon Railway The London and Croydon Railway (L&CR) was an early railway in England. It opened in 1839 and in February 1846 merged with other railways to form the London, Brighton and South Coast Railway (LB&SCR). Origins The Croydon line and other railways ...

Norwood Junction railway station Norwood Junction is an interchange station between the Windrush line of the London Overground and National Rail services operated by Southern (Govia Thameslink Railway), Southern and Thameslink and Great Northern, Thameslink, located in South No ...

to carry its

atmospheric railway An atmospheric railway uses differential air pressure to provide power for propulsion of a railway vehicle. A static power source can transmit motive power to the vehicle in this way, avoiding the necessity of carrying mobile power generating e ...

vehicles over the

Brighton Main Line The Brighton Main Line is a railway line in southern England linking London to Brighton. It starts at two termini in the capital, and , and the branches from each meet at , from where the route continues southwards via to the coast. The line ...

Highway and road

In North American usage, a ''flyover'' is a high-level overpass, built above main overpass lanes, or a bridge built over what had been an

at-grade intersection An intersection or an at-grade junction is a junction where two or more roads converge, diverge, meet or cross at the same height, as opposed to an interchange, which uses bridges or tunnels to separate different roads. Major intersections ar ...

. Traffic engineers usually refer to the latter as a ''

''. A flyover may also be an extra ramp added to an existing interchange, either replacing an existing cloverleaf loop (or being built in place of one) with a higher, faster ramp that eventually bears left, but may be built as a right or left exit. A cloverleaf or partial cloverleaf contains some 270 degree loops, which can slow traffic and can be difficult to construct with multiple lanes. Where all such turns are replaced with flyovers (perhaps with some underpasses) only 90 degree turns are needed, and there may be four or more distinct levels of traffic. Depending upon design, traffic may flow in all directions at or near open road speeds (when not congested). For more examples, see Freeway interchange.

Pedestrian

A pedestrian overpass allows traffic to pass without affecting

pedestrian A pedestrian is a person traveling on foot, by wheelchair or with other mobility aids. Streets and roads often have a designated footpath for pedestrian traffic, called the '' sidewalk'' in North American English, the ''pavement'' in British En ...

safety.

Railway

Railway overpasses are used to replace

level crossing A level crossing is an intersection where a railway line crosses a road, Trail, path, or (in rare situations) airport runway, at the same level, as opposed to the railway line or the road etc. crossing over or under using an Overpass#Railway, o ...

s (at-grade crossings) as a safer alternative. Using overpasses allows for unobstructed rail traffic to flow without conflicting with vehicular and pedestrian traffic.

Rapid transit Rapid transit or mass rapid transit (MRT) or heavy rail, commonly referred to as metro, is a type of high-capacity public transport that is generally built in urban areas. A grade separation, grade separated rapid transit line below ground su ...

systems use complete grade separation of their

rights of way A right of way (also right-of-way) is a specific route that people, animals, vehicles, watercraft, or utility lines travel, or the legal status that gives them the right to do so. Rights-of-way in the physical sense include controlled-access h ...

to avoid traffic interference with frequent and reliable service. Railroads also use

balloon loop A balloon loop, turning loop, or reversing loop ( North American Terminology) allows a rail vehicle or train to reverse direction without having to shunt or stop. Balloon loops can be useful for passenger trains and unit freight trains. Bal ...

s and

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 ...

s instead of flat junctions, as a way to reverse direction and to avoid trains conflicting with those on other tracks.

Gallery

Overpasses in Spain.JPG, Overpasses near

Barcelona Barcelona ( ; ; ) is a city on the northeastern coast of Spain. It is the capital and largest city of the autonomous community of Catalonia, as well as the second-most populous municipality of Spain. With a population of 1.6 million within c ...

Cumberland Highway.jpg, Cumberland Highway overpasses a street in

Sydney Sydney is the capital city of the States and territories of Australia, state of New South Wales and the List of cities in Australia by population, most populous city in Australia. Located on Australia's east coast, the metropolis surrounds Syd ...

Los Angeles Freeway Interchange.jpg, A high-capacity

stack interchange A directional interchange, colloquially known as a stack interchange, is a type of grade-separated junction between two controlled-access highways that allows for free-flowing movement to and from all directions of traffic. These interchanges e ...

: the Judge Harry Pregerson Interchange in

Los Angeles Los Angeles, often referred to by its initials L.A., is the List of municipalities in California, most populous city in the U.S. state of California, and the commercial, Financial District, Los Angeles, financial, and Culture of Los Angeles, ...

SandgateRailOverpass.JPG, Sandgate Flyover, New South Wales, where two main railway lines pass over two dedicated coal lines South entrance of Zheng Qi Overpass 20110114.jpg, Zheng Qi overpass,

Taipei , nickname = The City of Azaleas , image_map = , map_caption = , pushpin_map = Taiwan#Asia#Pacific Ocean#Earth , coordinates = , subdivision_type = Country ...

Overpass-NYThruway-355.25-c.jpg, New York State Thruway overpass Pedestrian overpass.JPG, Pedestrian overpass, I-64,

St. Louis St. Louis ( , sometimes referred to as St. Louis City, Saint Louis or STL) is an independent city in the U.S. state of Missouri. It lies near the confluence of the Mississippi and the Missouri rivers. In 2020, the city proper had a populatio ...

Missouri Missouri (''see #Etymology and pronunciation, pronunciation'') is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it border ...

. This overpass is located at the St. Louis Science Center. Sion Panvel Highway Kharghar exit.jpeg, A road sign on

Sion Panvel Highway The Sion Panvel Expressway is a 25 km Indian highway located entirely in the state of Maharashtra, that connects Sion in Mumbai with Panvel, via Navi Mumbai. It is one of the busiest and most important roads in the Mumbai Metropolitan Re ...

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

instructing travellers to use flyover for onward journey. Burbank Ave I-5 overpass under construction in Burbank, California.JPG, Overpass under construction over

Interstate 5 Interstate 5 (I-5) is the main north–south Interstate Highway System, Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific coast of the contiguous U.S. from Mexico to Canada. It travels thro ...

Burbank, California Burbank is a city in the southeastern end of the San Fernando Valley in Los Angeles County, California, United States. Located northwest of downtown Los Angeles, Burbank had a Census-estimated population of 102,755 as of 2023. The city was ...

, July 2021 Athens-Kiffisia-aerial.jpg, Round overpass in

Athens Athens ( ) is the Capital city, capital and List of cities and towns in Greece, largest city of Greece. A significant coastal urban area in the Mediterranean, Athens is also the capital of the Attica (region), Attica region and is the southe ...

General Holmes Drive from aircraft window.jpg, Sydney airport taxiway going over a major road. Welcome to New Jersey Turnpike Southbound Edgewood Road Bridge 2023.jpg, Sign welcoming drivers to the

New Jersey Turnpike The New Jersey Turnpike (NJTP) is a system of controlled-access highway, controlled-access toll roads in the U.S. state of New Jersey. The turnpike is maintained by the New Jersey Turnpike Authority (NJTA).The Garden State Parkway, although ma ...

under the Edgewood Road Bridge in

Leonia, New Jersey Leonia is a Borough (New Jersey), borough in Bergen County, New Jersey, Bergen County, in the U.S. state of New Jersey. As of the 2020 United States census, the borough's population was 9,304, an increase of 367 (+4.1%) from the 2010 United Sta ...

References

External links

* {{Infrastructure Bridges Railway buildings and structures Road infrastructure pl:Estakada