Overpass
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An overpass, called an overbridge or flyover (for a road only) in the United Kingdom and some other Commonwealth countries, is a bridge, road, railway or similar structure that is over another road or railway. An overpass and underpass together form a grade separation.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }} Search for [Separation, Grade].</ref> Stack interchanges are made up of several overpasses.
HistoryEdit
The world's first railroad flyover was constructed in 1843 by the London and Croydon Railway at Norwood Junction railway station to carry its atmospheric railway vehicles over the Brighton Main Line.<ref>Template:Cite book</ref>
Highway and roadEdit
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. Traffic engineers usually refer to the latter as a grade separation. 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.
PedestrianEdit
A pedestrian overpass allows traffic to pass without affecting pedestrian safety.
RailwayEdit
Railway overpasses are used to replace level crossings (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 systems use complete grade separation of their rights of way to avoid traffic interference with frequent and reliable service.
Railroads also use balloon loops and flying junctions instead of flat junctions, as a way to reverse direction and to avoid trains conflicting with those on other tracks.
GalleryEdit
- Overpasses in Spain.JPG
Overpasses near Barcelona
- Cumberland Highway.jpg
Cumberland Highway overpasses a street in Sydney
- Los Angeles Freeway Interchange.jpg
A high-capacity stack interchange: the Judge Harry Pregerson Interchange in 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
- Overpass-NYThruway-355.25-c.jpg
New York State Thruway overpass
- Pedestrian overpass.JPG
Pedestrian overpass, I-64, St. Louis, Missouri. This overpass is located at the St. Louis Science Center.
- Sion Panvel Highway Kharghar exit.jpeg
A road sign on Sion Panvel Highway in India 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 in Burbank, California, July 2021
- Athens-Kiffisia-aerial.jpg
Round overpass in Athens
- 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 under the Edgewood Road Bridge in Leonia, New Jersey