Compression arch suspended-deck bridge

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Truss arch suspended-deck bridge

Sydney Harbour Bridge, arguably the most famous of this type
Ancestor:	Truss arch bridge
Related:	None
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 compression arch suspended-deck bridge, or through arch bridge, is a bridge made from modern materials such as steel or reinforced concrete in which a compression arch rises above the deck. Cables connect the deck to the arch.

One of the most famous bridges of this type is the Sydney Harbour Bridge in Australia. The Bayonne Bridge, in the New York City metro area, is very similar and slightly longer.

[edit] 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
The Silver Jubilee Bridge (Runcorn-Widnes)	The Auckland Harbour Bridge from Watchman Island, west of it.	The Tyne Bridge, in green, with many of the Tyne's other bridges pictured behind it.	16th Street Bridge in Pittsburgh, Pennsylvania, USA
Fremont Bridge in Portland, Oregon, USA.	Compression arch suspended-deck bridge (foreground), beam bridge in background	Bayonne Bridge, connecting Bayonne, New Jersey with Staten Island, New York, USA	Kobe bridge, Kobe, Japan
Nijmegen Waalbridge	M60 New Dunnow Walk, Manchester, an accommodation bridge recently built over the M60.	The Hell Gate Bridge shortly after its completion.	Stanley Ferry Aqueduct, Yorkshire, opened 1839, built in cast iron.