Through arch bridge

Through arch bridge

Sydney Harbour Bridge, arguably the most famous of this type
Ancestor	Truss arch bridge
Related	None(see Suspension bridge)
Descendant	Tilt bridge
Carries	Pedestrians, vehicles, light rail, sometimes heavy rail
Span range	Medium
Material	Steel
Movable	No
Design effort	High
Falsework required	Seldom

A through arch bridge, also known as a half-through arch bridge and through-type arch bridge, is a bridge made from materials such as steel or reinforced concrete in which an arch rises above the deck so it passes through the arch. Cables in tension suspend the deck from the arch.

One of the most famous bridges of this type is the Sydney Harbour Bridge in Australia. The Hell Gate Bridge in New York City, the Bayonne Bridge in New Jersey, which is longer than the Sydney Harbour Bridge, as well as the smaller, near-twin Bourne Bridge and Sagamore Bridge over the Cape Cod Canal, are very similar.

Construction sequence

In some locations it is not practical to support the arch from beneath during construction.

In modern construction, temporary towers are erected and supported by cables anchored in the ground. Temporary cables fly from each side to support arch segments as they are constructed. When the arches are almost complete a jacking bridge is placed over or beneath the gap to force the arches apart, whence the final section is constructed in place or lifted into position.

In some cases, this type of arch has been created by constructing cantilevers from each side, with the shoreside ends bolted securely down into heavy piers. The incomplete channel ends are then constructed toward each other and either filled by construction or by lifting a prefabricated center section. This type of construction can be seen in the Sydney Harbour Bridge illustrated above.

• Images
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  The Hell Gate Bridge shortly after its completion.

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  Stanley Ferry Aqueduct, Yorkshire, opened 1839, built in cast iron.

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  1905 Arch Bridge Bellows Falls, Vermont

See also

• Arch bridge
• List of the largest arch bridges
• Tied arch bridge

References

• Demetrios E. Tonias; Jim J. Zhao. Bridge Engineering. ISBN 0071459030. http://books.google.com/books?id=B1HipIuozEQC&pg=PT40.