Inside the Arch of Sydney Harbour Bridge

The history of the Sydney Harbour Bridge goes back to 1914 when J.J.C. Bradfield was appointed "Chief Engineer of Sydney Harbour Bridge and Metropolitan Railway Construction". Bradfield is known as the "father" of the bridge. His original preference at the time was for a cantilever bridge without piers, and in 1916 the NSW Legislative Assembly passed a bill for such a construction, however it did not proceed as the Legislative Council rejected the legislation on the basis that the money would be better spent on the war effort.

Following World War I, plans to build the bridge again built momentum. Bradfield persevered with the project, fleshing out the details of the specifications and financing for his cantilever bridge proposal, and in 1921 he travelled overseas to investigate tenders. On return from his travels Bradfield decided that an arch design would also be suitable and he prepared a general design for a single-arch bridge based upon New York City's Hell Gate Bridge. In 1922 the government passed the Sydney Harbour Bridge Act No. 28, specifying the construction of a high-level cantilever or arch bridge across the harbour between Dawes Point and Milsons Point, along with construction of necessary approaches and electric railway lines, and worldwide tenders were invited for the project.

As a result of the tendering process, the Government received twenty proposals from six companies; on 24 March 1924 the contract was awarded to the English firm Dorman Long and Co Ltd, of Middlesbrough, who built the similar Tyne Bridge of Newcastle Upon Tyne. The arch design was cheaper than alternative cantilever and suspension bridge proposals, and also provided greater rigidity making it better suited for the heavy loads expected.

Bradfield oversaw the bridge design and building, while Dorman Long and Co's Consulting Engineer, Sir Ralph Freeman carried out the detailed design and erection process of the bridge. Architects for the contractors were from John Burnet & Partners of Glasgow, Scotland.

The building of the bridge coincided with the construction of the system of underground railways in Sydney's CBD, known today as the City Circle. The bridge was designed to carry six lanes of road traffic, flanked on each side by two railway tracks and a footpath. Both sets of rail tracks were linked into the underground Wynyard railway station on the south side of the bridge by ramps and tunnels. The eastern-side railway tracks were used to carry trams from the North Shore into a terminal within Wynyard station, and when tram services were discontinued in 1958, they were converted into extra traffic lanes.

The official ceremony to mark the "turning of the first sod" took place on 28 July 1923, at Milsons Point on the north shore.

An estimated 469 buildings on the north shore, both private homes and commercial operations, were demolished to allow construction to proceed, with little or no compensation being paid. Work on the bridge itself commenced with the construction of approaches and approach spans, and by September 1926 concrete piers to support the approach spans were in place on each side of the harbour.

As construction of the approaches took place, work was also started on preparing the foundations required to support the enormous weight of the arch and loadings. Concrete and granite faced abutment towers were constructed, with the angled foundations built into their sides.

Once work had progressed sufficiently on the support structures, a giant "creeper crane" was erected on each side of the harbour. These cranes were fitted with a cradle, and then used to hoist men and materials into position to allow for erection of the steelwork. To stabilise works while building the arches, tunnels were excavated on each shore with steel cables passed through them and then fixed to the upper sections of each half-arch to stop them collapsing as they extended outwards.

Arch construction itself began on 26 October 1928. The southern end of the bridge was worked on ahead of the northern end, to detect any errors and to help with alignment. The cranes would "creep" along the arches as they were constructed, eventually meeting up in the middle. In less than two years, on Tuesday, 19 August 1930, the two halves of the arch touched for the first time. Workers riveted both top and bottom sections of the arch together, and the arch became self-supporting, allowing the support cables to be removed. On 20 August 1930 the joining of the arches was celebrated by flying the flags of Australia and the United Kingdom from the jibs of the creeper cranes.

Once the arch was completed, the creeper cranes were then worked back down the arches, allowing the roadway and other parts of the bridge to be constructed from the centre out. The vertical hangers were attached to the arch, and these were then joined with horizontal crossbeams. The deck for the roadway and railway were built on top of the crossbeams, with the deck itself being completed by June 1931, and the creeper cranes were dismantled. Rails for trains and trams were laid, and road was surfaced using concrete topped with asphalt.

On 19 January 1932, the first test train, a steam locomotive, safely crossed the bridge.Load testing of the bridge took place in February 1932, with the four rail tracks being loaded with as many as 96 steam locomotives positioned end-to-end. The bridge underwent testing for three weeks, after which it was declared safe and ready to be opened.

Sixteen workers died during construction, but only two from falling off the bridge. Several more were injured from unsafe working practices undertaken whilst heating and inserting its rivets, and the deafness experienced by many of the workers in later years was blamed on the project.

The Sydney Harbour Bridge was opened on 19 March 1932 by the Governor of NSW and the Labor Premier Jack Lang. The opening was disrupted by a right wing group called the New Guard who were allegedly angry that no member of the British Royal Family had been invited to open the Bridge.

The total financial cost of the bridge was AU£6.25 million, which was not paid off in full until 1988!

Thanks to Wikilpedia for information.
Photo taken during Bridge Climb with Bridge Climb party.