luna park sydney 3
Luna Park Sydney spring 2005
Image available for purchase from www.ballaratheritage.com.au
Sydney Harbour Bridge
Source: Go to the National Heritage List for more information.
Location: Bradfield Hwy, Dawes Point - Milsons Point
Government: North Sydney City
Significance: The building of the Sydney Harbour Bridge was a major event in Australia's history, representing a pivotal step in the development of modern Sydney and one of Australia’s most important cities.Â The bridge is significant as a symbol of the aspirations of the nation, a focus for the optimistic forecast of a better future following the Great Depression.Â With the construction of the Sydney Harbour Bridge, Australia was felt to have truly joined the modern age, and the bridge was significant in fostering a sense of collective national pride in the achievement.
The Sydney Harbour Bridge was an important economic and industrial feat in Australia's history and is part of the nationally important story of the development of transport in Australia.Â The bridge is significant as the most costly engineering achievement in the history of modern Australia, and this was extraordinary feat given that it occurred at the severest point of the Great Depression in Australia.
The bridge is also significant for its aesthetic values.Â Since its opening in 1932, the Sydney Harbour Bridge has become a famous and enduring national icon, and remains Australia’s most identifiable symbol.Â In its harbour setting, it has been the subject for many of Australia’s foremost artists, and has inspired a rich and diverse range of images in a variety of mediums – paintings, etchings, drawings, linocuts, photographs, film, poems, posters, stained glass - from its construction phase through to the present.
The Sydney Harbour Bridge is also significant as one of the world's greatest arch bridges.Â Although not the longest arch span in the world, its mass and load capacity are greater than other major arch bridges, and no other bridge in Australia compares with the Sydney Harbour Bridge in its technical significance.Â In comparing Sydney Harbour Bridge with overseas arch bridges, Engineers Australia has drawn attention to its complexity in combining length of span with width and load carrying capacity.Â The construction of Sydney Harbour Bridge combined available technology with natural advantages provided by the site.Â The designers took advantage of the sandstone base on which Sydney was built, which enabled them to tie back the support cables during construction of the arch, and to experiment with massive structures.Â Although designed more than 80 years ago, the bridge has still not reached its loading capacity.
The bridge is also significant for its important association with the work of John Job Crew Bradfield, principal design engineer for the New South Wales Public Works Department, who ranks as one of Australia's greatest civil, structural and transport engineers.
Description: The Sydney Harbour Bridge includes a steel arch spanning the harbour between Milson's Point on the north side and Dawes Point on the south side, and elevated approaches to the arch from both the north and south sides.
The total length of the bridge, including the approach spans, is 1149 metres.Â The arch is made up of two 28-panel arch trusses set in vertical planes, 30 metres apart centre to centre, and braced together laterally; it is 57 metres deep beside the pylons and 18 metres deep in the middle of the arch (Godden Mackay, 1992: ref no 0076).Â It is anchored by two bearings at each end, which take the weight of the bridge and allow for expansion and contraction of the steel.Â Under maximum load, the thrust is approximately 20,000 tonnes on each bearing (Australian Government, Culture and Recreation Portal).
The span of the arch is 503 metres and the top of the arch is 134 metres above mean sea level.Â The arch is founded on sandstone rock excavated to a depth of 12 metres and filled with mass concrete.Â A total of 39,000 tonnes of structural steel was used in the arch, over two-thirds of it silicon steel (Australian Academy of Technological Sciences and Engineering, 2000).Â Two granite-faced concrete pylons, with a height of 89 metres above mean sea level, are located at each end of the arch (Australian Government, Culture and Recreation Portal).
A deck carrying road and rail traffic is suspended from the arch.Â Pairs of hangers, ranging in length from 7.3 metres to 58.8 metres, support cross-girders, each weighing 110 tonnes.Â The cross-girders support the concrete bridge deck (Nicholson, 2000: 26-27).Â The width of the deck is almost 49 metres and the clearance for shipping is also 49 metres.Â The deck currently caters for eight lanes of road traffic, two railway tracks, and two pedestrian footways.
The northern and southern approaches each contain five spans, constructed as pairs of parallel-chord, six-panel steel trusses.Â The spans are supported by pairs of concrete piers faced with granite (Nicholson, 2000: 10-11).Â The combined length of the approach spans is 646 metres.