Editing Bridge (section)

==Types of bridge==
[[File:Penrith Walk Bridge.jpg|thumb|124x124px|Victoria Bridge, Penrith NSW Australia]]
Bridges can be categorized in several different ways. Common categories include the type of structural elements used, by what they carry, whether they are fixed or movable, and by the materials used.

===Structure types===
Bridges may be classified by how the actions of [[Tension (mechanics)|tension]], [[compression (physical)|compression]], [[bending]], [[torsion (mechanics)|torsion]] and [[Shear stress|shear]] are distributed through their structure. Most bridges will employ all of these to some degree, but only a few will predominate. The separation of forces and moments may be quite clear. In a [[Suspension bridge|suspension]] or [[cable-stayed bridge]], the elements in tension are distinct in shape and placement. In other cases the forces may be distributed among a large number of members, as in a truss.
{{Clear}}
{| class="wikitable"
|-
| style="text-align:center;"|[[File:BeamBridge-diagram.svg|200px]]'''Beam bridge'''
|[[Beam bridges]] are horizontal beams supported at each end by substructure units and can be either ''[[simply supported]]'' when the beams only connect across a single span, or ''continuous'' when the beams are connected across two or more spans. When there are multiple spans, the intermediate supports are known as [[bridge pier|piers]]. The earliest beam bridges were simple logs that sat across streams and similar simple structures. In modern times, beam bridges can range from small, wooden beams to large, steel boxes. The vertical force on the bridge becomes a [[Shear stress|shear]] and [[Bending|flexural]] load on the beam which is transferred down its length to the substructures on either side<ref name="beambridge">{{cite web | url=http://www.design-technology.org/beambridges.htm | title=Beam bridges | publisher=Design Technology | access-date=14 May 2008 | url-status=live | archive-url=https://web.archive.org/web/20080518121256/http://www.design-technology.org/beambridges.htm | archive-date=18 May 2008 | df=mdy-all }}</ref> They are typically made of steel, concrete or wood. [[Girder bridge]]s and [[plate girder bridge]]s, usually made from steel, are types of beam bridges. [[Box girder bridge]]s, made from steel, concrete, or both, are also beam bridges. Beam bridge spans rarely exceed {{convert|250|ft|m}} long, as the flexural stresses increase proportionally to the square of the length (and deflection increases proportionally to the 4th power of the length).<ref>[http://www.engineersedge.com/beam_bending/beam_bending1.htm Structural Beam Deflection Stress Bending Equations / Calculation Supported on Both Ends Uniform Loading] {{webarchive|url=https://archive.today/20130122060213/http://www.engineersedge.com/beam_bending/beam_bending1.htm |date=22 January 2013 }}. ''Engineers Edge''. Retrieved on 23 April 2013.</ref> However, the main span of the [[Rio–Niteroi Bridge]], a box girder bridge, is {{convert|300|m|ft}}.<ref>{{cite book |author1=de Vasconcelos, Augusto Carlos |title=Handbook of International Bridge Engineering |author2=Marchesini, Gilson L. |author3=Timerman, Júlio |date=2014 |publisher=CRC Press |isbn=978-1-4398-1029-3 |editor1=Chen, Wai-Fah |location=Boca Raton, Florida |pages=184–186 |chapter=4.4 Steel Box Bridges |editor2=Duan, Lian |chapter-url=https://books.google.com/books?id=fYcAAQAAQBAJ&pg=PA184 |accessdate=26 July 2015}}</ref>

The world's longest beam bridge is [[Lake Pontchartrain Causeway]] in southern [[Louisiana]] in the United States, at {{convert|23.83|mi|km}}, with individual spans of {{convert|56|ft|m}}.<ref>{{cite magazine|date=28 May 1956|title=A big prefabricated bridge|magazine=[[Life (magazine)|Life]]|volume=40|issue=22|pages=53–60}}</ref> Beam bridges are the simplest and oldest type of bridge in use today,<ref>{{cite web|url=http://www.asceville.org/cw_bridges_explore.html|title=Civil What?!: Explore Bridges|website=ASCEville |access-date=2 February 2017|url-status=live|archive-url=https://web.archive.org/web/20170203161112/http://www.asceville.org/cw_bridges_explore.html|archive-date=3 February 2017}}</ref> and are a popular type.<ref>{{Cite journal|title=Forensic Examination of a Noncomposite Adjacent Precast Prestressed Concrete Box Beam Bridge|journal=Journal of Bridge Engineering|volume=15|issue=4|doi=10.1061/(ASCE)BE.1943-5592.0000110|year=2010|pages=408–418 | last1 = Naito | first1 = Clay | last2 = Sause | first2 = Richard | last3 = Hodgson | first3 = Ian | last4 = Pessiki | first4 = Stephen | last5 = Macioce | first5 = Thomas|issn=1084-0702 }}</ref>
|-
| style="text-align:center;"|[[File:TrussBridge-diagram.svg|200px]]'''Truss bridge'''
| A [[truss bridge]] is a bridge whose load-bearing superstructure is composed of a truss. This truss is a structure of connected elements forming triangular units. The connected elements (typically straight) may be stressed from tension, compression, or sometimes both in response to dynamic loads.<ref>[https://books.google.com/books?id=A3oSAAAAYAAJ Science and Industry] {{Webarchive|url=https://web.archive.org/web/20170215092202/https://books.google.com/books?id=A3oSAAAAYAAJ |date=2017-02-15 }}, Members of a Truss Bridge by Benj. F. La Rue, Home Study Magazine, Published by the Colliery Engineer Company, Vol 3, No. 2, March 1898, pages 67–68.</ref> Truss bridges are one of the oldest types of modern bridges. The basic types of truss bridges shown in this article have simple designs which could be easily analyzed by nineteenth and early twentieth-century engineers. A truss bridge is economical to construct owing to its efficient use of materials.
|-
| style="text-align:center;"|[[File:CantileverBridge-diagram.svg|200px]]'''Cantilever bridge'''
|[[Cantilever bridge]]s are built using [[cantilever]]s—horizontal beams supported on only one end. Most cantilever bridges use a pair of [[continuous span]]s that extend from opposite sides of the supporting piers to meet at the center of the obstacle the bridge crosses. Cantilever bridges are constructed using much the same materials and techniques as beam bridges. The difference comes in the action of the forces through the bridge.

Some cantilever bridges also have a smaller beam connecting the two cantilevers, for extra strength.

The longest cantilever bridge is the single-spanned {{conv|549|m}} [[Quebec Bridge]] of 1919 in Quebec, Canada. It took this title from the [[Forth Bridge]] of 1890, spanning between [[North Queensferry|North]] and [[South Queensferry]], [[Edinburgh]], Scotland with a double-span of {{conv|521|m}} each.
|-
| style="text-align:center;"|[[File:ArchBridge-diagram.svg|200px]]'''Arch bridge'''
|[[Arch bridge]]s have [[abutments]] at each end. The weight of the bridge is thrust into the [[abutments]] at either side. The earliest known arch bridges were built by the Greeks, and include the [[Arkadiko Bridge]].

With the span of {{convert|220|m}}, the [[Solkan Bridge]] over the [[Soča]] River at [[Solkan]] in Slovenia is the second-largest stone bridge in the world and the longest railroad stone bridge. It was completed in 1905. Its arch, which was constructed from over {{convert|5000|t}} of stone blocks in just 18 days, is the second-largest stone arch in the world, surpassed only by the Friedensbrücke (Syratalviadukt) in [[Plauen]], and the largest railroad stone arch. The arch of the Friedensbrücke, which was built in the same year, has the span of {{convert|90|m|0|abbr=on}} and crosses the valley of the [[Syrabach]] River. The difference between the two is that the Solkan Bridge was built from stone blocks, whereas the Friedensbrücke was built from a mixture of crushed stone and cement mortar.<ref>{{cite conference |url=https://books.google.com/books?id=E7ywmb24EQMC&q=%22world+famous+arch+bridges+in+slovenia%22&pg=PA121 |title=World Famous Arch Bridges in Slovenia |language=en, fr |author=Gorazd Humar |date=September 2001 |publisher=Presses des Ponts |book-title=Arch'01: troisième Conférence internationale sur les ponts en arc Paris |editor=Charles Abdunur |pages=121–124 |location=Paris |isbn=2-85978-347-4 |url-status=live |archive-url=https://web.archive.org/web/20160730012023/https://books.google.com/books?id=E7ywmb24EQMC&lpg=PA121&dq=%22world%20famous%20arch%20bridges%20in%20slovenia%22&pg=PA121#v=onepage&q=%22world%20famous%20arch%20bridges%20in%20slovenia%22&f=false |archive-date=30 July 2016}}</ref>

The world's largest arch bridge is the [[Chaotianmen Bridge]] over the [[Yangtze River]] with a length of {{convert|1741|m|ft|0|abbr=on}} and a span of {{convert|552|m|ft|0|abbr=on}}. The bridge was opened 29 April 2009, in [[Chongqing]], China.<ref name=Chaotianmen>{{cite web | url=http://www.guinnessworldrecords.com/records-1/longest-bridge-steel-arch-bridge/# | publisher=Guinness World Records | access-date=18 February 2013 | title=Longest bridge, steel arch bridge | archive-url=https://web.archive.org/web/20131019124452/http://www.guinnessworldrecords.com/records-1/longest-bridge-steel-arch-bridge/ | archive-date=19 October 2013 | df=mdy-all }}</ref>
|-
| style="text-align:center;"|[[File:TiedarchBridge-diagram.svg|200px]]'''Tied&nbsp;arch bridge'''
|[[Tied-arch bridge]]s have an arch-shaped superstructure, but differ from conventional arch bridges. Instead of transferring the weight of the bridge and traffic loads into thrust forces into the abutments, the ends of the arches are restrained by tension in the bottom chord of the structure.<ref>{{cite web |url=http://www.bath.ac.uk/ace/uploads/StudentProjects/Bridgeconference2009/Papers/MASKELL.pdf |title=A Critical Analysis of North Shore Footbridge, Stockton-on-Tees, UK |first=Daniel |last=Maskell |work=Proceedings of Bridge Engineering 2 Conference 2009 |publisher=bath.ac.uk |year=2009 |access-date=11 December 2009 |quote=Under vertical  dead  loads  and  uniform  imposed  loads  the arches  support  the  loads  under  pure  axial compression with  the  deck  edge  cables  acting  as  horizontal  ties.}}</ref> They are also called bowstring arches.
|-
| style="text-align:center;"|[[File:SuspensionBridge-diagram.svg|200px]]'''Suspension bridge'''
|[[Suspension bridges]] are suspended from cables. The earliest suspension bridges were made of ropes or vines covered with pieces of bamboo. In modern bridges, the cables hang from towers that are attached to caissons or cofferdams. The caissons or cofferdams are implanted deep into the bed of the lake, river or sea. Sub-types include the [[simple suspension bridge]], the [[stressed ribbon bridge]], the [[underspanned suspension bridge]], the [[suspended-deck suspension bridge]], and the [[self-anchored suspension bridge]]. There is also what is sometimes called a "semi-suspension" bridge, of which the [[Ferry Bridge, Burton|Ferry Bridge]] in Burton-upon-Trent is the only one of its kind in Europe.<ref>''A.O.P. Guide to Burton-on-Trent'', 1911, p. 13{{full citation needed|date=November 2019}}</ref>

The longest suspension bridge in the world is the {{convert|4608|m|0|abbr=on}} [[1915 Çanakkale Bridge]] in Turkey.
|-
| style="text-align:center;"|[[File:CableStayedBridge-diagram.svg|200px]]'''Cable-stayed bridge'''
|[[Cable-stayed bridge]]s, like suspension bridges, are held up by cables. However, in a cable-stayed bridge, less cable is required and the towers holding the cables are proportionately higher.<ref name=cable>{{cite web | url=http://www.newton.dep.anl.gov/askasci/eng99/eng99373.htm | title=Cable Stay vs Suspension Bridges | first=Andy | last=Johnson | publisher=U.S. Department of Energy | url-status=live | archive-url=https://web.archive.org/web/20080518142005/http://www.newton.dep.anl.gov/askasci/eng99/eng99373.htm | archive-date=18 May 2008 | df=mdy-all }}</ref> The first known cable-stayed bridge was designed in 1784 by C. T. (or C. J.) Löscher.<ref>{{cite book|url = https://books.google.com/books?id=AhSgrMcT4sgC&q=loescher+cable-stayed&pg=PA5 |title = Cable Stayed Bridges|page = 7|url-status = live|first =René|date = 1999 |last=Walther | publisher=Thomas Telford |archive-url=https://web.archive.org/web/20161115132533/https://books.google.ca/books?id=AhSgrMcT4sgC&pg=PA5&lpg=PA5&dq=loescher+cable-stayed&source=bl&ots=Ldmb12QZ67&sig=Au-TF0YlWc2pQOrtw7CmDufITds&hl=en&sa=X&ei=LfenUZXOLqri0QGCtoFo&ved=0CCwQ6AEwAA |archive-date=15 November 2016 |isbn = 978-0-7277-2773-2}}</ref><ref>{{cite web|url = http://www.contech.co.nz/uploaded/Marcel%20Poser%20-%20Cable%20Stayed%20Structures%20and%20Stay%20Cable%20Technology.pdf |title = Cable Stayed Structures and Stay Cable Technology|last = Poser|first =Marcel |archive-url=https://web.archive.org/web/20130209123954/http://www.contech.co.nz/uploaded/Marcel%20Poser%20-%20Cable%20Stayed%20Structures%20and%20Stay%20Cable%20Technology.pdf |archive-date=9 February 2013 }}</ref>

The longest cable-stayed bridge since 2012 is the {{convert|1104|m|0|abbr=on}} [[Russky Bridge]] in [[Vladivostok]], Russia.<ref>{{cite news|work=The Guardian|date=2 July 2012|author=Elder, Miriam|location=London|title=Russian city of Vladivostok unveils record-breaking suspension bridge|url=https://www.theguardian.com/world/2012/jul/02/russian-vladivostok-record-suspension-bridge|access-date=3 February 2016|url-status=live|archive-url=https://web.archive.org/web/20160120162508/http://www.theguardian.com/world/2012/jul/02/russian-vladivostok-record-suspension-bridge|archive-date=20 January 2016}}</ref>
|}

Some Engineers sub-divide 'beam' bridges into slab, beam-and-slab and box girder on the basis of their cross-section.<ref name=":1" /> A slab can be solid or [[hollow-core slab|voided]] (though this is no longer favored for inspectability reasons) while beam-and-slab consists of concrete or steel girders connected by a concrete slab.<ref name=":2" /> A [[Box girder bridge|box-girder]] cross-section consists of a single-cell or multi-cellular box. In recent years, [[integral bridge]] construction has also become popular.

===Fixed or movable bridges===
{{Redirect|Fixed link|other uses|Intercontinental and transoceanic fixed links|and|Link (disambiguation)}}
[[File:AVLB 01.jpg|thumb|Alvis Unipower TBT (tank bridge transporter) of the British army]]
Most bridges are fixed bridges, meaning they have no moving parts and stay in one place until they fail or are demolished. Temporary bridges, such as [[Bailey bridge]]s, are designed to be assembled, taken apart, transported to a different site, and re-used. They are important in military engineering and are also used to carry traffic while an old bridge is being rebuilt. [[Movable bridge]]s are designed to move out of the way of boats or other kinds of traffic, which would otherwise be too tall to fit. These are generally electrically powered.<ref>{{Cite book|last=Hovey|first=Otis Ellis|title=Movable bridges|publisher=John Wiley & Sons, Inc.|year=1927|location=New York|pages=1–2|hdl=2027/mdp.39015068174518}}</ref>

The tank bridge transporter (TBT) has the same cross-country performance as a tank even when fully loaded. It can deploy, drop off and load bridges independently, but it cannot recover them.<ref>{{cite web |url=http://army.mod.uk/royalengineers/equipment/702.aspx |title=Close Support Bridging (CSB) - British Army Website |publisher=Army.mod.uk |accessdate=2012-08-07 |archive-url=https://web.archive.org/web/20111126032356/http://army.mod.uk/royalengineers/equipment/702.aspx |archive-date=2011-11-26 |url-status=live }}</ref>

===Double-decked bridges{{Anchor|Double-decked}}===
{{See also|List of multi-level bridges}}
[[File:George Washington Bridge from New Jersey-edit.jpg|thumb|The double-decked [[George Washington Bridge]], connecting New York City and [[Bergen County, New Jersey]], is the world's busiest bridge, carrying 106 million vehicles annually.<ref name="panynj.gov">{{cite web |url=http://www.panynj.gov/bridges-tunnels/george-washington-bridge.html |access-date=14 February 2023|title=Port Authority of New York and New Jersey – George Washington Bridge |publisher=The Port Authority of New York and New Jersey |url-status=live |archive-url=https://web.archive.org/web/20130920192211/http://www.panynj.gov/bridges-tunnels/george-washington-bridge.html |archive-date=20 September 2013}}</ref>]]

Double-decked (or double-decker) bridges have two levels, such as the [[George Washington Bridge]], connecting New York City to [[Bergen County]], [[New Jersey]], US, as the world's busiest bridge, carrying 102 million vehicles annually;<ref name="panynj.gov"/><ref name=abcgwb>{{cite web|url=https://abcnews.go.com/US/george-washington-bridge-painters-dangerous-job-top-worlds/story?id=17771877|title=GW Bridge Painters: Dangerous Job on Top of the World's Busiest Bridge|author1=Bod Woodruff|author2=Lana Zak|author3=Stephanie Wash|name-list-style=amp|work=ABC News|date=20 November 2012|access-date=13 September 2013|url-status=live|archive-url=https://web.archive.org/web/20130928002159/https://abcnews.go.com/US/george-washington-bridge-painters-dangerous-job-top-worlds/story?id=17771877|archive-date=28 September 2013}}</ref> [[truss]] work between the roadway levels provided stiffness to the roadways and reduced movement of the upper level when the lower level was installed three decades after the upper level. The [[Tsing Ma Bridge]] and [[Kap Shui Mun Bridge]] in Hong Kong have six lanes on their upper decks, and on their lower decks there are two lanes and a pair of tracks for [[MTR]] metro trains. Some double-decked bridges only use one level for street traffic; the [[Washington Avenue Bridge (Minneapolis)|Washington Avenue Bridge]] in [[Minneapolis]] reserves its lower level for automobile and light rail traffic and its upper level for pedestrian and bicycle traffic (predominantly students at the [[University of Minnesota]]). Likewise, in [[Toronto]], the [[Prince Edward Viaduct]] has five lanes of motor traffic, bicycle lanes, and sidewalks on its upper deck; and a pair of tracks for the [[Bloor–Danforth line|Bloor–Danforth]] [[Toronto subway and RT|subway line]] on its lower deck. The western span of the [[San Francisco–Oakland Bay Bridge]] also has two levels.

[[Robert Stephenson]]'s [[High Level Bridge, River Tyne|High Level Bridge]] across the [[River Tyne]] in [[Newcastle upon Tyne]], completed in 1849, is an early example of a double-decked bridge. The upper level carries a railway, and the lower level is used for road traffic. Other examples include [[Britannia Bridge]] over the [[Menai Strait]] and [[Craigavon Bridge]] in Derry, Northern Ireland. The [[Øresund Bridge|Oresund Bridge]] between [[Copenhagen]] and [[Malmö]] consists of a four-lane highway on the upper level and a pair of railway tracks at the lower level. [[Tower Bridge]] in London is different example of a double-decked bridge, with the central section consisting of a low-level [[Bascule bridge|bascule span]] and a high-level [[footbridge]].

===Viaducts===
{{main|Viaduct}}
A viaduct is made up of multiple bridges connected into one longer structure. The longest and some of the highest bridges are viaducts, such as the [[Lake Pontchartrain Causeway]] and [[Millau Viaduct]].

===Multi-way bridge===
{{main|Multi-way bridge}}
[[File:Tridge Undercarriage.jpg|thumb|The [[The Tridge (Midland, Michigan)|Tridge]], a [[multi-way bridge]] in [[Midland, Michigan]], U.S.]]
A multi-way bridge has three or more separate spans which meet near the center of the bridge. Multi-way bridges with only three spans appear as a "T" or "Y" when viewed from above. Multi-way bridges are extremely rare. [[The Tridge (Midland, Michigan)|The Tridge]], [[Margaret Bridge]], and [[Y-Bridge (Zanesville, Ohio)|Zanesville Y-Bridge]] are examples.

{{anchor|road bridge}}

===Bridge types by use===
A bridge can be categorized by what it is designed to carry, such as trains, pedestrian or road traffic ('''road bridge'''), a pipeline ('''Pipe bridge''') or waterway for water transport or barge traffic. An [[aqueduct (bridge)|aqueduct]] is a bridge that carries water, resembling a viaduct, which is a bridge that connects points of equal height. A road-rail bridge carries both road and rail traffic. Overway is a term for a bridge that separates incompatible intersecting traffic, especially road and rail.<ref>{{cite news |url=http://nla.gov.au/nla.news-article170491612 |title=The Mile-End Crossing |newspaper=[[The Observer (Adelaide)|The Observer]] |volume=LXXXI |issue=6,004 |location=South Australia |date=23 February 1924 |access-date=26 March 2018 |page=16 |via=National Library of Australia}}</ref>

Some bridges accommodate other purposes, such as the tower of [[Nový Most]] Bridge in [[Bratislava]], which features a restaurant, or a [[bridge-restaurant]] which is a bridge built to serve as a restaurant. Other suspension bridge towers carry transmission antennas.<ref>{{cite journal |last1=Roberts |first1=Gethin |last2=Brown |first2=Christopher |last3=Tang |first3=Xu |last4=Ogundipe |first4=Oluporo |date=February 2015 |title=Using satellites to monitor Severn Bridge structure, UK |journal=Proceedings of the Institution of Civil Engineers - Bridge Engineering |volume=168 |issue=4 |pages=330–339 |doi=10.1680/bren.14.00008 |url=http://bura.brunel.ac.uk/handle/2438/12192 }}</ref>

Conservationists use [[Wildlife crossing|wildlife overpasses]] to reduce [[habitat fragmentation]] and animal-vehicle collisions.<ref>{{Cite web|last=Greenfield|first=Patrick|date=23 January 2021|title=How creating wildlife crossings can help reindeer, bears – and even crabs|url=http://www.theguardian.com/environment/2021/jan/23/how-wildlife-crossings-are-helping-reindeer-bears-and-even-crabs-aoe|url-status=live|archive-url=https://web.archive.org/web/20210123083528/https://www.theguardian.com/environment/2021/jan/23/how-wildlife-crossings-are-helping-reindeer-bears-and-even-crabs-aoe |archive-date=23 January 2021 |access-date=2021-01-26|website=The Guardian|language=en}}</ref> The first [[Wildlife crossing|animal bridges]] sprung up in France in the 1950s, and these types of bridges are now used worldwide to protect both large and small wildlife.<ref>{{cite news|title=Animals Need Infrastructure Too|author=Sarah Holder|date=31 July 2018|newspaper=Bloomberg.com|access-date=21 February 2019|url=https://www.citylab.com/life/2018/07/wildlife-crossings-bridges-tunnels-animals-roads-highways-roadkill/566210/}}</ref><ref>{{cite web|title=Bridges for Animals to Safely Cross Freeways Are Popping Up Around the World|date=9 February 2017|access-date=21 February 2019|website=My Modern Met|author=Jessica Stewart|url=https://mymodernmet.com/wildlife-crossings/}}</ref><ref>{{cite web|title=World's Coolest Animal Bridges|author=Rachel Newer|date=23 July 2012|website=Smithsonian.com|access-date=21 February 2019|url=https://www.smithsonianmag.com/smart-news/worlds-coolest-animal-bridges-5774855/}}</ref>

Bridges are subject to unplanned uses as well. The areas underneath some bridges have become makeshift shelters and homes to homeless people, and the undertimbers of bridges all around the world are spots of prevalent graffiti. Some bridges attract people attempting suicide, and become known as [[suicide bridge]]s.<ref>{{Cite journal|last=Glasgow|first=Garrett|date=1 March 2011|title=Do local landmark bridges increase the suicide rate? An alternative test of the likely effect of means restriction at suicide-jumping sites|url=http://www.sciencedirect.com/science/article/pii/S0277953611000384|journal=Social Science & Medicine|language=en|volume=72|issue=6|pages=884–889|doi=10.1016/j.socscimed.2011.01.001|pmid=21320739|issn=0277-9536|url-access=subscription}}</ref><ref>{{cite web | last=Marsh | first=Julia | title=Port Authority not liable for NYC bridge jumpers: judge | date=30 December 2018 | url=https://nypost.com/2018/12/30/george-washington-bridge-jumpers-only-have-themselves-to-blame-judge/ | work=[[New York Post]] | access-date=3 January 2019}}</ref>

===Bridge types by material===
[[File:Ironbridge 6.jpg|thumb|[[The Iron Bridge]] in Shropshire, England, completed in 1781, the first cast iron bridge]]
[[File:Kraemerbruecke und Aegidienkirche Erfurt 2017.jpg|thumb|[[Krämerbrücke]] in [[Erfurt]], Germany, a bridge with [[half timbered]] buildings]]
[[File:Stone bridge, Othoni island.jpg|thumb|A small stone bridge in [[Othonoi]], Greece]]
The materials used to build the structure are also used to categorize bridges. Until the end of the 18th century, bridges were made out of timber, stone and masonry. Modern bridges are currently built in concrete, [[Steel bridge|steel]], fiber reinforced polymers (FRP), stainless steel or combinations of those materials. [[Living root bridges|Living bridges]] have been constructed of live plants such as ''[[Ficus elastica]]'' tree roots in India<ref>{{Cite news|url=https://livingrootbridges.com/methods-of-creating-living-root-bridges/|title=How are Living Root Bridges Made?|date=5 May 2017|work=The Living Root Bridge Project|access-date=8 September 2017|url-status=live|archive-url=https://web.archive.org/web/20170905002548/https://livingrootbridges.com/methods-of-creating-living-root-bridges/|archive-date=5 September 2017}}</ref> and [[wisteria]] vines in Japan.<ref>{{cite web|url=http://www.atlasobscura.com/places/vine-bridges-japan|title=The Vine Bridges of Iya Valley|website=Atlas Obscura|access-date=8 September 2017|url-status=live|archive-url=https://web.archive.org/web/20170908110829/http://www.atlasobscura.com/places/vine-bridges-japan|archive-date=8 September 2017}}</ref>

{| class="wikitable"
|-
! Bridge type !! Materials used
|-
| Cantilever || For small footbridges, the cantilevers may be simple beams; however, large cantilever bridges designed to handle road or rail traffic use trusses built from [[structural steel]], or box girders built from [[prestressed concrete]].<ref>{{cite web|title=Cantilever|url=http://www.bridgesofdublin.ie/bridge-building/types/cantilever|website=Bridges of Dublin|url-status=live|archive-url=https://web.archive.org/web/20141029131006/http://www.bridgesofdublin.ie/bridge-building/types/cantilever|archive-date=29 October 2014}}</ref>
|-
| Suspension || The cables are usually made of [[steel cable]]s galvanised with [[zinc]],{{citation needed|reason=Galvanising is rare on highly stressed structural wires as it can cause cracking.|date=September 2016}} along with most of the bridge, but some bridges are still made with steel-[[reinforced concrete]].<ref>{{cite web|title=Suspension Bridges|url=http://www.madehow.com/Volume-5/Suspension-Bridge.html|website=Made How|url-status=live|archive-url=https://web.archive.org/web/20150102202158/http://www.madehow.com/Volume-5/Suspension-Bridge.html|archive-date=2 January 2015}}</ref>
|-
| Arch || [[Stone]], brick and other such materials that are strong in compression and somewhat so in shear.
|-
| Beam || Beam bridges can use pre-stressed concrete, an inexpensive building material, which is then embedded with [[rebar]]. The resulting bridge can resist both compression and tension forces.<ref>{{cite web|title=Beam Bridges |work = Nova Online|url=https://www.pbs.org/wgbh/nova/lostempires/china/meetbeam.html|publisher=PBS|url-status=live|archive-url= https://web.archive.org/web/20150106053043/http://www.pbs.org/wgbh/nova/lostempires/china/meetbeam.html|archive-date= 6 January 2015}}</ref>
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| Truss ||The triangular pieces of truss bridges are manufactured from straight and steel bars, according to the truss bridge designs.<ref>{{cite web|last1=K|first1=Aggeliki|last2=Stonecypher|first2=Lamar|title=Truss Bridge Designs|url=http://www.brighthubengineering.com/structural-engineering/63635-truss-bridge-designs/|website=Bright Hub Engineering|url-status=live|archive-url=https://web.archive.org/web/20150219192803/http://www.brighthubengineering.com/structural-engineering/63635-truss-bridge-designs/|archive-date=19 February 2015|date=10 February 2010}}</ref>
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