Editing Overpass

{{Short description|Bridge, road, railway, or similar structure that crosses over another road or railway}}
{{Other uses}}
{{Use American English|date=March 2021}}
{{Use mdy dates|date=March 2021}}
[[File:I-73 at I-840 Overpasses Aerial - Facing South (50698132631).jpg|thumb|right|Highway [https://www.google.com/maps/place/Greensboro,+NC/@36.1182339,-79.9086607,62a,38.7y,151.47h,68.46t/data=!3m1!1e3!4m6!3m5!1s0x8853193f38c77b79:0x93b9c49478be12c8!8m2!3d36.0725632!4d-79.791534!16zL20vMGtjdzI?entry=ttu&g_ep=EgoyMDI0MTAxNS4wIKXMDSoASAFQAw%3D%3 overpass] in [[Greensboro, North Carolina]]]]
[[File:020 N700 Series Shinkansen 新幹線 arriving at Kyoto Station, Japan.jpg|thumb|right|Overpass crossing multiple railway lines and roads in [[Kyoto]], Japan]]
[[File:HK STT 石塘咀 Shek Tong Tsui Hill Road flyover bridge December 2021 Px3 02.jpg|thumb|In [[Hong Kong]], an overpass is built along a street or road, like [[Hill Road, Hong Kong|Hill Road Flyover]], to alleviate traffic between two main roads.]]

An '''overpass''', called an '''overbridge''' or '''flyover''' (for a road only) in the United Kingdom and some other [[Commonwealth of Nations|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>{{cite web |url=http://www.ebooksread.com/authors-eng/institute-of-traffic-engineers/traffic-engineering-handbook-hci/page-46-traffic-engineering-handbook-hci.shtml |title=Read the ebook Traffic engineering handbook by Institute of Traffic Engineers |author=Henry K. Evans |year=1950 |work=ENGINEERING HANDBOOK, Second Edition 1950 |publisher=Institute of Traffic Engineers |location=New Haven, Connecticut |via= eBooksRead.com |access-date=2010-10-09 |archive-date=2012-03-18 |archive-url=https://web.archive.org/web/20120318064658/http://www.ebooksread.com/authors-eng/institute-of-traffic-engineers/traffic-engineering-handbook-hci/page-46-traffic-engineering-handbook-hci.shtml |url-status=dead}} Search for [Separation, Grade].</ref> [[Stack interchange]]s are made up of several overpasses.

==History==
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>{{cite book |last=Turner |first=J.T. Howard |title=The London Brighton and South Coast Railway 1. Origins and formation |publisher=Batsford |year=1977 |location=London |page=249 |isbn=978-0-7134-0275-9 |via=[[Internet Archive]] |url=https://archive.org/details/londonbrightonso0000turn_t7e4/page/249/mode/1up?view=theater&q=flyover+%22the+first+in+the+world%22 }}</ref>

==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]]. 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 interchange|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 separation structure|pedestrian overpass]] allows traffic to pass without affecting [[pedestrian]] safety.

==Railway==
Railway overpasses are used to replace [[level crossing]]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]] systems use complete grade separation of their [[Right-of-way (transportation)|rights of way]] to avoid traffic interference with frequent and reliable service.

Railroads also use [[balloon loop]]s and [[flying junction]]s instead of [[flat junction]]s, as a way to reverse direction and to avoid trains conflicting with those on other tracks.

==Gallery==
<gallery mode="packed" heights="160px">
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, [[Interstate 64 in Missouri|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 California|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]]
</gallery>

==See also==
* [[Footbridge]]
* [[Skyway]]
* [[Stack interchange]]
* [[Viaduct]]
* [[Wildlife crossing]]

==References==
{{reflist}}

== External links ==
* {{Commons category inline}}

{{Road types}}
{{Infrastructure}}

[[Category:Bridges]]
[[Category:Railway buildings and structures]]
[[Category:Road infrastructure]]

[[pl:Estakada]]