Friday, 11 November 2011

Landmark Bridges of Australia

On 2 March 2004, Australia Post  issue the stamp series features landmark bridges. This issue designed by Gary Domoney. The featured bridges in this commemorative stamp issue span Australia’s history and show a diversity of construction materials and styles ranging from the stone bridge of convict days to the engineering and architectural wonders of current times. The bridges are ‘landmarks’ because of their physical position and status, or their historic or engineering qualities. 

Ross Bridge, Tasmania:
Spanning the Macquarie River, the elegant Ross Bridge was completed in 1836 and is regarded as the finest masonry bridge of its period. It is renowned for its decorative carved stonework depicting Celtic symbols and images of contemporary figures.

Government engineer John Lee Archer was commissioned to build the bridge, and although Archer designed it, credit for its construction belongs to two convict stonemasons, James Colbeck and Daniel Herbert, who were emancipated on completion of the bridge. 
The sandstone bridge has three equal arches and is flanked at each corner by curved flights of stone steps sweeping down to the river banks. However the bridge’s real distinction comes from the 186 carvings on the arches. 
Some of the carvings are symbolic or iconographic. Others are representational, depicting people, dogs and other animals, birds, sheaves of wheat and bales of wool, and so on.

Lockyer Creek Bridge, Queensland:
Located between Helidon and Murphy’s Creek the Lockyer Creek Bridge was built in 1911, and is one of two similar cast-in-situ reinforced concrete arch railway bridges in this locality.
The bridge has three spans, each supported on two arches. This elegant bridge was a major engineering achievement at the time, and is still one of the largest spans of its type in Australia. 

Lockyer Creek Bridge, which still carries main line rail traffic, has been placed on the Queensland Heritage Register.In Australia concrete arch railway bridges are unique to Queensland and South Australia.

Sydney Harbour Bridge, New South Wales:
As Australia’s most famous bridge, and one of the largest single-arch steel bridges in the world, links Sydney’s central city with North Sydney.
It carries eight lanes of road traffic and two railway tracks, a footway and a cycle path. Since 1998 the bridge has also become an adventure destination for thousands of tourists who undertake the acclaimed Bridge Climb®.

The arch, which was built out progressively from each shore, was joined successfully on the night of 19 August 1930. Over the next 18 months the steel decking was hung from the arch and the roadway completed.
The four pylons at each end of the bridge are purely decorative. They were made of concrete and faced with granite, transported to the site by three purpose-built ships.

Birkenhead Bridge, South Australia:
Built in 1940 Birkenhead Bridge services both road and shipping traffic for South Australia’s major port, Port Adelaide.
The twin bascule span bridge crosses the upper reaches of the Port River and links the LeFevre Peninsula with the Adelaide metropolitan area.  

‘Bascule’ refers to the ‘see-saw’ action of the lifting mechanism. Each leaf or slab of the bridge is counterbalanced with weights inside the bases of the structure, allowing them to tilt upwards to allow ships through without using too much power. The bridge opens for vessels which cannot otherwise pass under it. 

Bolte Bridge, Victoria:
With its four spans the six-lane Bolte Bridge is one of the largest balanced cantilever cast-in-situ box girder bridges in Australia. Bolte Bridge crosses the Yarra River west of the city of Melbourne.
The bridge is a vital part of City Link, a city bypass designed to minimise traffic crossing the city centre and relieve traffic congestion on arterial and local roads. 

Five land-based piers support the bridge. The central pier is set on a man-made island in the middle of the river.Although they serve no structural purpose the elegant twin towers at the centre of the bridge are its distinguishing feature. Made of reinforced concrete, the slender towers create a dramatic visual focal point and a powerful new landmark for Melbourne.

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