Before The Bridge:

After the arrival of the first fleet in 1788, the colony, while initially concerned with survival in a hostile environment, soon began to spread, west, south and finally northwards. The first settlement of the north occurred in 1794 when several isolated colonies were founded. In 1817 the first "ferry " service consisted of a rowing boat operated by emancipated convict Billy Blue between Millers Point and the north. During the 1840s, settlement of the north shore became more widespread, and bridges at Gladesville and Lane Cove were constructed, thus reducing the route form Sydney to North Sydney to 20 kilometres. Ferry patronage increased dramatically with the opening of a rail line to North Sydney and Milsons Point. The need for an alternative Harbour crossing became apparent in the 1900s, and planning began immediately to find the best solution.

As the colony neared its centennial, Sir Henry Parkes, the premier at the time, appointed a Royal Commission to investigate the possibility of constructing a harbour crossing. After many proposals were rejected, John Job Crew Bradfield, the Principal Designing Engineer in the Department of Public Works, advised that a bridge and subway as had earlier been suggested would not be suitable, and recommended the construction of a single span bridge. As a result of his recommendations he was appointed Chief Engineer, Sydney Harbour Bridge and Metropolitan Railway Construction in 1912, before the actual scheme had been agreed on !

In 1914, Bradfield was sent to Europe to investigate the latest engineering technology involved in constructing single span bridge and underground railway construction. In 1922 he was again sent abroad to examine new tenders for construction of the new bridge. Tenders were opened in January 1924, with six companies proposing 20 design types. One of the seven tenders for a two-hinged steel arch bridge, from Dorman Long and Company Limited of Middlesborough, England was accepted on 24th of March,1924. The contract price was 4,217,721 pounds, 11 shillings and 10 pence.

Design :

The Sydney Harbour Bridge is a two-hinged steel arch, with a steel deck hanging from the arch and five steel truss approach spans leading to the side of the arch. The arch is hinged at the base on each side of the harbour, these hinges allow the bridge to expand and contract and take the full weight of the bridge through large solid sandstone skewbacks. The structure can easily cope with temperature variations of 49 degrees Celsius and withstand winds of up to 200 kilometres an hour.

Originally designed to carry four rail lines, six road lanes and two footways, the designed loading allows for completely congested road, rail and footways. The steelwork in the bridge supports a variety of components : 63% is needed to hold up the dead weight of the bridge, 25% for the live load, 5% for wind pressure, 5% for the affect of temperature, and 2% to allow for the braking of trains. The pylons are mainly decorative. They are hollow structures which help to firm the foundations, and are faced with granite.

Construction :

The "Turning of the First Sod" occurred at present day North Sydney Railway Station on 28 July, 1923. The acquisition and demolishing of buildings began in earnest on 28 July, 1924. The excavations for the foundations of the main bearings and approach span piers commenced in January 1925. As well as composing part of the foundations of the bearings, the "skewbacks" also formed part of the base of the pylons and abutment towers. Pylon construction above the deck level didn't occur until the main arch had been joined and the support cables removed.

The approach spans were constructed from the inshore ends towards the harbour, and their ends rest on their respective abutment tower. The granite facing on the pylons and piers was quarried near Moruya in NSW, 300 kilometres south of Sydney. 18,000 cubic metres of rock facing were used in construction, and wastage was crushed and used in the concrete of the bridge.

Two harbourside workshops were established to make the steelwork. One "light" workshop and a "heavy" workshop were established, with the heavy workshop obviously constructing the heavier and larger sections of the bridge. These workshops were located at the original Milsons Point Railway Station. The workshops were dismantled immediately after use.

The arch was constructed in two halves, holding each half back with steel cables anchored in large U-shaped tunnels dug into the rock. After the approach spans and abutment towers had been constructed to deck level, work began on the main arch. Giant creeper cranes were built and assembled on temporary ramps on the abutment towers. As the first sections of the arch were built, the cranes moved onto the sections and erected the second sections, before creeping on and building the next section, and so on. The erection of the arch commenced on 26 October 1928, and by August 1930 the two halves were ready to be joined. The steel cables were slackened in a process that required round the clock supervision. The process began on 7 August 1930, and by 10pm on 19 August, the two halves were linked and the north and south city was joined for the first time.

Every worker involved in releasing the cables was given a golden sovereign, and all the other workers were given two shillings with which to toast the new bridge. A half-holiday was declared for all the workers. The cables were removed and the stressing of the top chord of the arch was carried, out and thus the arch was converted to a two hinge structure. The deck was constructed from the centre of the bridge outwards, as the creeper cranes were already in the centre of the structure. All the steel work of the deck had been completed by May 1931.

The railway lines were placed on each side of the western hangars, the vehicle lanes placed in the centre, and the footways were on the extreme outside. The heavier load was supported by the hangar, thus making the cross beams lighter and reducing the overall weight of the structure.

The two creeper cranes were dismantled by June 1931, and by 1932 the asphalt surface of the deck and the pylons had been completed. In February 1932, the bridge was load tested, and after three weeks of tests the bridge was found to have complied with all the specifications. Overhead wiring was completed in March of that year.

Opening The Bridge :

The opening of the Sydney Harbour Bridge on Saturday, 19th March 1932 was a source of great pride to the people of Sydney who were in the throes of a Depression. The celebrations which marked this historic day were remarkable. At 10am the Premier, J T Lang, after reading a message from King George V, cut the ribbon and declared the bridge officially open. However this opening was not without incident. Irishman Francis De Groot attempted to stop Premier Lang from opening the bridge by racing to the ribbon on horseback and slashing it with his sword. He was arrested and eventually fined five pounds for damaging Government property (a ribbon!); at the ceremony, the ribbon was hastily tied back together and events proceeded a scheduled. Commemorative tablets were unveiled by the Premier and the Governor of New South Wales, Sir Philip Game. The opening of the bridge was broadcast direct to Britain and America, highlighting the importance of the occasion. The followed a parade two kilometres long with colourful floats and displays.

A procession of ships and boats was also organised as well as a fireworks display, a display by the Royal Australian Air Force, sporting events, a carnival and other festivities which lasted for well over a week. The opening day (excepting Children's Day, on 16 March 1932) was the first time that pedestrians were not confined to the footways on the bridge. Each traverser was given a souvenir ticket to mark the great day. New stamps and telegrams were issued by the post office. The only other occasion on which the deck of the bridge has been opened up to 'human' traffic was on the 60th anniversary of the opening of the bridge in 1982

Modern Day Harbour Bridge :

The current cost of maintaining the Harbour Bridge is well over $2 million a year, and part of these costs were financed by the introduction of a one way toll collection for vehicles travelling from the north of the city to the south.

Various other changes to the approachways to the bridge have occurred over the years. In the late 1950s the tram lines were converted to a new roadway known as the Cahill Expressway. The Warringah Freeway was the second major approachway to the bridge from the north of the city, and was opened on 18 June 1968 by Governor Cutler. The Western Distributor was opened in September 1972, and catered for traffic coming through the western and southern suburbs without going through the city centre.

A Driver Aid Scheme with electronic screens over each lane helps drivers find the correct lane for their preferred destination, and alerts them to any traffic situations which may need a change of lane. This allows traffic flow to remain as smooth as possible especially during peak traffic times. A Tow Truck service is in operation to remove broken down vehicles from traffic lanes, thus ensuring fast flow of traffic over the bridge.

The bridge cost $20 million to build and was only paid off in 1988. The Sydney Harbour Bridge is a world famous landmark, and an engineering achievement that is a source of pride to Sydneysiders and a major tourist attraction in Sydney, second only to the Sydney Opera House.

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