Editing Suspension bridge (section)

===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.