Bradfield's Bridge

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introduction

The idea of a bridge to cross the harbour dates back to as early as 1815 when Francis Greenway proposed the building of a bridge from Dawes Point to the North Shore. It was not until 1900 however, that a competition was held for designs and financial proposals for such a bridge. Some twenty four schemes submitted but none were thought to be acceptable, even though one design in 1903, by the firm of J. Stewart and Co., for a single arch bridge without pylons, was very similar to the one that exists today.

Over the next eighteen years, under the guidance of one of Australia's greatest ever engineers, John Job Crew Bradfield (1867-1943), who was later to graduate from the University Of Sydney, the bridge project was to take shape. Numerous reports were prepared on bridges, railways and all forms of communications and a contract was issued in 1921. In the end an international competition was held, with Bradfield responsible for setting the parameters and suggesting that the design should be an arch bridge with granite-faced pylons at either end. Ultimately Bradfield and his staff were to oversee all of the design and building process.

The winning design, Number A3, was one of six alternatives submitted by the English firm of Dorman and Long. This was for a single arch to be built from both ends using cable supports, and joined in the middle. The contract was signed in March 1924. Dorman Long and Co.'s Consulting Engineer, Sir Ralph Freeman, then carried out the detailed design which was similar to that of the Hell Gate Bridge in New York.

Work began on the Bridge in 1924, with the demolition of 800 houses to allow for the construction of the bridge approaches and the approach spans. At this time foundations 12 metres deep and set in sandstone on were prepared either side of the harbour to take four steel thrust bearings. Anchoring tunnels some 36 metres long were dug into the bedrock at each end.

Construction of the arch began in November, 1929. The arch and roadway were manufactured in sections on a site on the western side of Milsons Point, in an area that is now occupied by Luna Park. About eighty percent of the steel used was shipped from England while the remaining twenty percent was manufactured in Australia.

The arch was built from both sides of the harbour at the same time with steel cable restraints initially supporting each side. These met in October and the construction of the deck then proceeded from the middle outwards towards each shore as it was easier not to move the construction cranes back to the pylons. The four pylons, which are mainly aesthetic, were built of concrete covered by grey granite from Moruya on the south coast of New South Wales.

The Harbour Bridge was officially opened on 19 March 1932, after being stress tested by loading it with train engines, trams and buses to check its load bearing capacity. The total cost of the Bridge was approximately 6.25 million Australian pounds ($A12.5 million), and was eventually paid off in 1988.

Some of the materials displayed here are from the personal collection of the chief engineer, Dr John Job Crew Bradfield, and are the gift of his son Dr Keith Noel Everal Bradfield. Others are from the collection of W.H. Lush, the designing engineer, and are the gift of Mrs B.M. Lush and Miss E. Lush.

View photographs of the building of the Sydney Harbour Bridge.

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