Editing Suspension bridge (section)

==History==
{{For|bridges where the deck follows the suspenders|simple suspension bridge}}

The earliest suspension bridges were ropes slung across a chasm, with a deck possibly at the same level or hung below the ropes such that the rope had a [[catenary arch|catenary]] shape.

===Precursors===
[[File:Old Chain-Bridge at Chaksam.jpg|thumb|[[Chushul Chakzam]], one of Thangtong Gyalpo's chain bridges, in 1904]]
[[File:Burr Bridge, Schenectady, NY.jpg|thumb|The wooden 1808 Burr Suspension Bridge in Schenectady, NY, USA, during demolition in 1871, showing wooden cables.<ref>{{cite web | url=https://www.bridgemeister.com/pic.php?pid=1785 | title=Bridgemeister - Mohawk Wooden Suspension Bridge }}</ref><ref>{{cite web | url=https://www.vizettes.com/kt/upstateny-history/historical/burr-bridge.htm | title=Burr Bridge - Scotia, NY }}</ref> Spans of 160, 190, 180 and 157 feet on 3 piers began to sag, and 4 supporting piers were added in 1833 making 8 spans.<ref>p.62, Schenectady and the Great Western Gateway, 1926, Schenectady, NY, Chamber of Commerce</ref>]]

The [[Tibetan people|Tibetan]] [[siddha]] and bridge-builder [[Thangtong Gyalpo]] originated the use of [[wrought iron|iron]] chains in his version of [[simple suspension bridge]]s. In 1433, Gyalpo built eight bridges in eastern [[Bhutan]]. The last surviving chain-linked bridge of Gyalpo's was the Thangtong Gyalpo Bridge in [[Duksum]] en route to [[Trashi Yangtse]], which was finally washed away in 2004.<ref>{{cite book|title=Bhutan|publisher=Lonely Planet|url=https://books.google.com/books?id=s-L8NUlW_QgC&pg=PA131|isbn=978-1-74059-529-2|year=2007}}</ref> Gyalpo's iron chain bridges did not include a [[suspended-deck bridge]], which is the standard on all modern suspension bridges today. Instead, both the railing and the walking layer of Gyalpo's bridges used wires. The [[stress (mechanics)|stress points]] that carried the [[screed]] were reinforced by the iron chains. Before the use of iron chains it is thought that Gyalpo used ropes from twisted willows or yak skins.<ref>{{cite book|title=Chakzampa Thangtong Gyalpo|year=2009|publisher=Centre for Bhutan Studies|page=61|doi=10.11588/xarep.00000311|url=http://archiv.ub.uni-heidelberg.de/savifadok/volltexte/2009/311/pdf/Chakzampa.pdf|url-status=live|archive-url=http://archive.wikiwix.com/cache/20140525105817/http://archiv.ub.uni-heidelberg.de/savifadok/volltexte/2009/311/pdf/Chakzampa.pdf|archive-date=25 May 2014|last1=Gerner|first1=Manfred|isbn=9789993614395}}</ref> He may have also used tightly bound cloth.

The [[Inca]] used [[Inca rope bridge|rope bridges]], documented as early as 1615. It is not known when they were first made. [[Queshuachaca]] is considered the last remaining Inca rope bridge and is rebuilt annually.

===Chain bridges===
[[File:A plan & view of a chain bridge - erecting over the menai at Bangor Ferry 1820.jpeg|thumb|200px|An early plan for the [[Menai Suspension Bridge|chain bridge]] over the [[Menai Strait]] near [[Bangor, Wales]], completed in 1826]]

The first iron [[Chain bridge|chain suspension bridge]] in the [[Western world]] was the [[Jacob's Creek Bridge]] (1801) in [[Westmoreland County, Pennsylvania]], designed by inventor [[James Finley (engineer)|James Finley]].<ref>{{cite web|title=Iron Wire of the Wheeling Suspension Bridge|publisher=Smithsonian Museum Conservation Institute|url=http://www.si.edu/mci/english/research/past_projects/iron_wire_bridge.html|url-status=live|archive-url=https://web.archive.org/web/20110430064802/http://www.si.edu/mci/english/research/past_projects/iron_wire_bridge.html|archive-date=30 April 2011}}</ref> Finley's bridge was the first to incorporate all of the necessary components of a modern suspension bridge, including a suspended deck which hung by trusses. Finley patented his design in 1808, and published it in the Philadelphia journal, [[The Port Folio]], in 1810.<ref>{{cite book|title=Bridges: Three Thousand Years of Defying Nature|publisher=MBI Publishing Company|url=https://books.google.com/books?id=ARwZhPVA6ZYC&pg=PA56|isbn=978-0-7603-1234-6|date=12 November 2001}}</ref>

Early British chain bridges included the [[Dryburgh Abbey Bridge]] (1817) and 137 m [[Union Bridge (Tweed)|Union Bridge]] (1820), with spans rapidly increasing to 176 m with the [[Menai Suspension Bridge|Menai Bridge]] (1826), "the first important modern suspension bridge".<ref>{{cite web|url=http://www.britannica.com/EBchecked/topic/374642/Menai-Bridge|title=Menai Bridge - bridge, Wales, United Kingdom|website=britannica.com|access-date=3 May 2018|url-status=live|archive-url=https://web.archive.org/web/20150413220655/http://www.britannica.com/EBchecked/topic/374642/Menai-Bridge|archive-date=13 April 2015}}</ref> The first chain bridge on the German speaking territories was the [[Chain Bridge (Nuremberg)|Chain Bridge]] in [[Nuremberg]]. The Sagar Iron Suspension Bridge with a 200 feet span (also termed Beose Bridge) was constructed near Sagar, India during 1828–1830 by Duncan Presgrave, Mint and Assay Master.<ref>[https://books.google.com/books?id=ZY9fAAAAcAAJ&dq=Beose+Bridge+sagar&pg=PA50 The Sagar Iron Suspension Bridge Mechanics Magazine Volume 2, 1836 p. 49-53]</ref> The [[Clifton Suspension Bridge]] (designed in 1831, completed in 1864 with a 214 m central span), is similar to the Sagar bridge. It is one of the longest of the parabolic arc chain type. The current [[Marlow Bridge|Marlow suspension bridge]] was designed by [[William Tierney Clark]] and was built between 1829 and 1832, replacing a wooden bridge further downstream which collapsed in 1828.  It is the only suspension bridge across the non-tidal Thames. The [[Széchenyi Chain Bridge]], (designed in 1840, opened in 1849), spanning the River Danube in Budapest, was also designed by William Clark and it is a larger-scale version of Marlow Bridge.<ref>"Marlow Suspension Bridge". Retrieved 11 December 2008. Cove-Smith, Chris (2006). The River Thames Book. Imray Laurie Norie and Wilson. {{ISBN|0-85288-892-9}}.{{page needed|date=July 2022}}</ref>
One variation is the [[Thornewill and Warham]]'s [[Ferry Bridge, Burton|Ferry Bridge]] in [[Burton-on-Trent]], [[Staffordshire]] (1889), where the chains are not attached to abutments as is usual, but instead are attached to the main girders, which are thus in compression.  Here, the chains are made from flat wrought iron plates, eight inches (203&nbsp;mm) wide by an inch and a half (38&nbsp;mm) thick, rivetted together.<ref>{{cite web |url=https://www.ice.org.uk/disciplines-and-resources/ice-library-and-digital-resources/historical-engineering-works/details?hewID=2746#details |title= ICE Library|website=www.ice.org.uk |archive-url=https://web.archive.org/web/20161025235610/https://www.ice.org.uk/disciplines-and-resources/ice-library-and-digital-resources/historical-engineering-works/details?hewID=2746 |archive-date=25 October 2016}}</ref>

===Wire-cable===
[[File:Manhattan_Bridge_2007.jpg|thumb|The [[Manhattan Bridge]], connecting [[Manhattan]] and [[Brooklyn]] in New York City, opened in 1909 and is considered to be the forerunner of modern suspension bridges; its design served as the model for many of the long-span suspension bridges around the world.]] The first wire-cable suspension bridge was the [[Spider Bridge at Falls of Schuylkill]] (1816), a modest and temporary footbridge built following the collapse of James Finley's nearby [[Chain Bridge at Falls of Schuylkill]] (1808). The footbridge's span was 124 m, although its deck was only 0.45 m wide.
[[File:Pont de Tournon-sur-Rhône de 1825.jpg|thumb|[[Marc Seguin]] suspension bridge near [[Annonay]], 1825]]

Development of wire-cable suspension bridges dates to the temporary simple suspension bridge at [[Annonay]] built by [[Marc Seguin]] and his brothers in 1822. It spanned only 18 m.<ref name="Peters"/> The first permanent wire cable suspension bridge was [[Guillaume Henri Dufour]]'s Saint Antoine Bridge in [[Geneva]] of 1823, with two 40 m spans.<ref name="Peters">{{cite book
|last = Peters
|first = Tom F. <!--
|first2=Andrea L. |last2=Peters
-->
|title = Transitions in Engineering: Guillaume Henri Dufour and the Early 19th Century Cable Suspension Bridges
|publisher = Birkhauser
|year = 1987
|isbn = 3-7643-1929-1
|url = https://books.google.com/books?id=73JPiTuDYscC
|url-status = live
|archive-url = https://web.archive.org/web/20140710053853/http://books.google.com/books?id=73JPiTuDYscC
|archive-date = 10 July 2014
}}</ref> The first with cables assembled in mid-air in the modern method was [[Joseph Chaley]]'s Grand Pont Suspendu in [[Fribourg]], in 1834.<ref name="Peters"/>

In the United States, the first major wire-cable suspension bridge was the [[Spring Garden Street Bridge#2nd bridge: Wire Bridge at Fairmount|Wire Bridge at Fairmount]] in Philadelphia, Pennsylvania. Designed by [[Charles Ellet Jr.]] and completed in 1842, it had a span of 109 m. Ellet's Niagara Falls suspension bridge (1847–48) was abandoned before completion. It was used as [[scaffolding]] for [[John A. Roebling]]'s [[Bridge#Double-decker bridge|double decker]] railroad and carriage bridge (1855).

The [[Otto Beit Bridge]] (1938–1939) was the first modern suspension bridge outside the United States built with parallel wire cables.<ref>[http://www.clevelandbridge.com/Gallery%20Historic.htm Cleveland Bridge Company (UK)] {{webarchive|url=https://web.archive.org/web/20080720172523/http://www.clevelandbridge.com/Gallery%20Historic.htm |date=20 July 2008 }} Web site Retrieved 21 February 2007, includes image of the bridge.</ref>

<gallery widths="200" heights="120">
File: Chaksam (Iron Bridge in transliteration from Tibetan to English).png|Drawing of the Tibetan-built Chaksam bridge south of [[Lhasa]], constructed in 1430, with long chains suspended between towers, and vertical suspender ropes carrying the weight of a planked footway below.
File: View of the Chain Bridge The Port Folio June 1810.jpg|''View of the Chain Bridge invented by James Finley Esq.'' (1810) by [[William Strickland (architect)|William Strickland]]. Finley's [[Chain Bridge at Falls of Schuylkill]] (1808) had two spans, 100 feet, and 200 feet.
File:Sagar Iron Suspension Bridge.png|Sagar Iron Suspension Bridge, by Major Presgrave, 1828–1830, near [[Sanodha]], [[Sagar district]] [[India]] constructed using locally produced iron.
File: The New Suspension Bridge at Fairmount, Philadelphia by George Lehman circa 1842.jpg|[[Spring Garden Street Bridge#2nd bridge: Wire Bridge at Fairmount|Wire Bridge at Fairmount]] (1842, replaced 1874).
</gallery>