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Railway viaduct

Viaduct
MiltonViaduct.jpg
Laigh Milton Viaduct in Ayrshire is the oldest surviving railway bridge in Scotland
Ancestor Trestle bridge, Box girder bridge
Related None
Descendant None
Carries Expressways, highways, streets, railways
Span range Short (multiple)
Material reinforced concrete, prestressed concrete, masonry
Movable No
Design effort medium
Falsework required available for use, since viaducts are all composed of low bridges.

A viaduct is a bridge composed of several small spans for crossing a valley, dry or wetland, or forming a flyover. The term viaduct is derived from the Latin via for road and ducere, to lead. The ancient Romans did not use the term; it is a modern derivation from an analogy with aqueduct. Like the Roman aqueducts, many early viaducts comprised a series of arches of roughly equal length. Viaducts may span land, water or both.

A viaduct is a bridge composed of several small spans for crossing a valley or a gorge. The term is conventional for a rail flyover as opposed to a flying junction or a rail bridge which crosses one feature. In Romance languages, the word viaduct refers to a bridge which spans only land. A bridge spanning water is called ponte.

The longest viaduct in antiquity may have been the Pont Serme which crossed wide marshes in southern France.

Viaducts are commonly used in many cities that are railroad centers, such as Chicago, Atlanta, Birmingham, London and Manchester. These viaducts cross the large railroad yards that are needed for freight trains there, and also cross the multi-track railroad lines that are needed for heavy railroad traffic. These viaducts keep highway and city street traffic from having to be continually interrupted by the train traffic. Likewise, some viaducts carry railroads over large valleys, or they carry railroads over cities with many cross-streets and avenues.


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