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Sydney Harbour Bridge - NSW

semi-overcast 22 °C

In 1922 after many years of debate, legislation authorised the construction of a bridge across Sydney Harbour.
A steel suspension bridge, though attractive, would not have offered the necessary load-bearing capacity. A cantilever bridge, though economically and technically viable, was less visually imposing than a steel arch. The winning design reflected the influence of New York's strong and handsome Hell Gate Bridge.
Building work commenced in 1924 and on 19th Aug. 1930 the half arch from the north shore finally met the half arch from the south shore. The work was completed over the following two years and the bridge was officially opened on 19th March 1932.
The construction of the Sydney Harbour Bridge involved the use of 52,800 tonnes of steel. steel expands as it warms up and contracts as it cools. To allow for the fact that the top of the arch actually rises and falls about 180mm due to temperature changes, hinges were incorporated into the design. These hinges or bearings support the full weight of the bridge. To stop the two side of the bridge collapsing during construction, steel cables were used to hold back the two halves, firmly anchored in 36 meter long horse-shoe shaped tunnels dug into the sandstone bedrock on both sides of the harbour. Each of the 128 cables weighed 8.5tonnes and was made up of 217 individual wires.
By 7th August 1930, the two half arches were finished., A gap of only one metre separated the two sides. The order was given to start slackening the tie-back cables, so that the two halves would line up and join together perfectly.
Below is a model of the centre pin that was used to fastened the two halves together. The pilot pin is about 2.5cm square, in section and about 215cm long.

The first challenge to investigate the bridge, was to find the staircase up!
Somewhere up this road is a small hole in the wall to Argyle stairs.
This led to the Bridge steps.
We started to walk across the bridge and at the first Pylon, went up!

The Pylon Lookout offers spectacular views of the bridge, the harbour and the city.

It's also about £100 cheaper than the bridge climb! You can see some crazy fools climbing the bridge here

The pylon staircase was built during the construction from 1924-1932.
Rivets were heated to white hot state in small furnaces located across the bridge, thrown to a catcher who passed them to a riveter who placed then and fixed them in position. Steel plates were transferred from barge to bridge by crane, often with a 'dogman' travelling with the load and then returning for the next 'delivery'. 'Tin Hares' manoeuvred each steel piece into position, fastening nuts and bolts and adjusting angles before riveting took place. Plates were bolted into position as a temporary measure until being riveted together.
There was little in the way of safety equipment - no hard hats, safety line, protective boots or special clothing.
You had to hang on by your eyelashes Tom Tomrop
There were six million rivets used in the bridge and in order to locate the holes an indent was made in the steelwork by hand with a punch - 'marking off'.

- On a hot day the steel expands and the bridge can grow up to 180mm
- It took 7 years and 356 days to build
- he arch span is 503m
- The bridge is 49m wide
- The pylons are 89m above sea level
- Approximately 6 million rivets were used to make the bridge. In the 1920's welding was too unreliable and nuts and bolts were quite expensive
- Constant inspections of the steel work are made and painting is carried out on a 'as required' basis - the bridge is not painted from one side to the other as is often assumed
- 272,000 litres of paint were required to give the bridge it's initial three coats
- An area of 485,000 square meters has to be painted
- The arch is 134m above sea level
- The bridge is 1,149m long including approach spans
- It is the third longest steel arch bridge in the world, but is considered the greates because of combination of span and load bearing capacity
- Originally there were six vehicle lanes, two train lines, two tram lines, a footway and a cycle way on the bridge. Now there are seven vehicle lllanes, one bus lane, two train lines, a footway and a cycleway.
- It cost 10,057,170 pounds, 7 shillings and 9 pence to build
- In 2000 161,000 vehicles crossed the bridge each day.
- A whole lot of cats used to live in the a roof-top cattery here! They were owned by Yvonne Rentoul who managed the 'All Australian Exhibition' between 1948 and 1971.

Views looking west

Views looking east

View of the iconic Sydney Opera house

It 'appened this way: I 'ad jist come down,
after long years, to look at Sydney town.
An' 'struth! Was I knocked endways?
Fair su'prised?
I never dreamed! That arch that cut the skies!
The Bridge! I never thort there could 'a' been -
I never knoo, nor guest I never seen...
Well, Sydney's 'ad some knocks since I been gone
But strike! This shows she keeps on keepin' on.

from 'I dips me lid' by C.J.Dennis


Posted by charlystyles 15:10 Archived in Australia Tagged sydney_harbour_bridge

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