ShortAns - SumComp - SentEnd - Constructing The Coathanger
The Sydney Harbour Bridge is a heritage-listed steel through arch bridge across Sydney Harbour that carries rail, vehicular, bicycle, and pedestrian traffic between the Sydney central business district (CBD) and the North Shore. The dramatic view of the bridge, the harbour, and the nearby Sydney Opera House is an iconic image of Sydney, and Australia itself. The bridge is nicknamed "The Coathanger" because of its arch-based design.
The building of the bridge was under the management of chief engineer John Bradfield. Three other people heavily involved in the bridge's design and construction were Lawrence Ennis, Edward Judge, and Sir Ralph Freeman. Ennis was the engineer-in-charge at Dorman Long and Co and the main on-site supervisor (Bradfield visited occasionally throughout the project and, in particular, at many key stages of the project, to inspect progress and make managerial decisions), Judge was chief technical engineer of Dorman Long, and Freeman was hired by the company to design the accepted model in further detail. Later a bitter disagreement broke out between Bradfield and Freeman as to who should be credited for the bridge’s design.
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 support 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. Power and telephone lines, and water, gas, and drainage pipes were also all added to the bridge in 1931.
The pylons were built atop the support towers, with construction advancing rapidly from July 1931. Carpenters built wooden scaffolding, with concreters and masons then setting the masonry and pouring the concrete behind it. Steel-workers built the steelwork in the towers, while day labourers manually cleaned the granite with wire brushes. The last stone of the north-west pylon was set in place on 15 January 1932, and the timber towers used to support the cranes were removed.
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. The construction worksheds were demolished after the bridge was completed.
The standards of industrial safety during construction were poor by today's standards. Sixteen workers died during construction, but surprisingly 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. Henri Mallard between 1930 and 1932 produced hundreds of stills and film footage which reveal at close quarters the bravery of the workers in tough Depression-era conditions.
The total financial cost of the bridge was AU£6.25 million, which was not paid off in full until 1988.