Editing Arch bridge (section)

===Aqueducts===
<gallery mode="packed" caption="[[Aqueduct (bridge)|Aqueducts]] — bridges carrying water-supply and [[navigable aqueduct]]s">
File:Pont du Gard BLS.jpg|The three-story Roman [[Pont du Gard]] [[Aqueduct (watercourse)|aqueduct]] near [[Nimes]], [[France]]
File:Aqueduct of Segovia 02.jpg|Roman [[Aqueduct of Segovia]], Spain
File:Tomar December 2008-4.jpg|The Aqueduto dos Pegões in [[Tomar]], [[Portugal]]
File:Vila do Conde 3.jpg|The Aqueduct of [[Vila do Conde]], Portugal with an distinct angular turn
File:Aquadukt, Kavala.jpg|16th-century Ottoman [[Kavala aqueduct]], [[Greece]] with both an distinct angular turn and a curve in the structure shown in an overhead image
File:1, Μεσαιωνικό υδραγωγείο Καμάρες Καβάλας (photosiotas).jpg|Kavala aqueduct near Nikotsara Square showing the curve of the structure from street level
File:Acueducto, Arcos del Sitio, Tepotzotlán.jpg|The colonial Aqueduct, [[Tepotzotlán]], [[State of Mexico]]
File:Vanvitelli aqueduct.jpg|right|[[UNESCO]] [[World Heritage Site]] [[Aqueduct of Vanvitelli]], [[Italy]], built by [[Luigi Vanvitelli]] 
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File:pontcysyllte aqueduct arp.jpg|UNESCO World Heritage Site [[Pontcysyllte Aqueduct]] carrying the [[Llangollen Canal]] by civil engineers [[Thomas Telford]] and [[William Jessop]] in [[Wales]], with a [[narrowboat]] crossing 
File:WalesC0047.jpg|The Pontcysyllte Aqueduct over the River Dee viewed from the Vale of [[Llangollen]], with a [[narrowboat]] crossing
File:Union icicle.jpg|The [[Almond Aqueduct]] carrying the [[Edinburgh and Glasgow Union Canal]] over [[River Almond, Lothian|River Almond]] at [[Ratho]] with a frozen overflow channel during the [[Winter of 2009–10 in Great Britain and Ireland|big freeze of 2010]]
File:Avon Aqueduct - geograph.org.uk - 1691980.jpg|The [[Avon Aqueduct]] carrying the [[Edinburgh and Glasgow Union Canal]] over the [[River Avon, Falkirk|Avon]] near [[Linlithgow]]
File:Dowley Gap Aqueduct - geograph.org.uk - 353210.jpg|The Dowley Gap or the Seven Arches Aqueduct by the civil engineer [[James Brindley]] carrying the [[Leeds and Liverpool Canal]] over the [[River Aire]], [[Yorkshire]]
File:Dundas Aqueduct, from south-east.jpg|The [[Dundas Aqueduct]] in [[Bath Stone]] by the civil engineer [[John Rennie (father)|John Rennie]] carrying the [[Kennet and Avon Canal]] over the [[River Avon, Bristol|River Avon]] and the [[Wessex Main Line]] railway at [[Limpley Stoke]], near [[Bath, Somerset|Bath]], [[England]]
File:Engine Arm Aqueduct east.jpg|The [[Engine Arm Aqueduct]], by the civil engineer [[Thomas Telford]] and cast by [[Horseley Ironworks]], carrying the [[Engine Arm]], a [[Birmingham Canal Navigations]] feeder, over the [[BCN Main Line]]
File:Engine Arm Aqueduct west.jpg|The Engine Arm Aqueduct close-up image showing the arch from below
</gallery>

In some locations it is necessary to span a wide gap at a relatively high elevation, such as when a canal or water supply must span a valley. Rather than building extremely large arches, or very tall supporting columns (difficult using stone), a series of arched structures are built one atop another, with wider structures at the base. Roman [[Civil engineering|civil engineers]] developed the design and constructed highly refined structures using only simple materials, equipment, and mathematics. This type is still used in canal viaducts and roadways as it has a pleasing shape, particularly when spanning water, as the reflections of the arches form a visual impression of circles or ellipses.

{{Anchor|Open-spandrel deck arch bridge}}
{{Anchor|Closed-spandrel deck arch bridge}}