Sydney Harbour Bridge

Sydney Harbour Bridge Quick Facts
Bridge Type: Steel Arch
Bridge Length: 1149m
Bridge Width: 49m
Construction Dates: 1923 – 1932
Designer: John Bradfield, Thomas S. Tait, Ralph Freeman
Construction Company: Dorman Long & Co Ltd.

Length of arch span: 503m
Height of top of arch: 134m
Height of pylons: 89m
Navigational Clearance: 53.4m

Opened in 1932, the Sydney Harbour Bridge is a steel arch bridge that carries rail, vehicular, bicycle and pedestrian traffic; and is affectionately nicknamed "The Coathanger" due to its design.

Under the direction of Dr J.J.C. Bradfield of the NSW Department of Public Works, the bridge was designed and built by British firm Dorman Long and Co Ltd, and remains the world’s tallest steel arch bridge.

Located between Millers Point (southern end) and Milsons Point (northern end) the bridge boasts eight lanes of road traffic through the main roadway, plus an additional two lanes of road traffic (which were once tram tracks). A path for pedestrians adjacent to the road traffic runs along the eastern side of the bridge, whilst a dedicated cycle path runs along the western side. Two railways tracks lie beside the main roadway (known as the Bradfield Highway, which at 2.4 km makes it one of the shortest highways in Australia).

The arch of the Sydney Harbour Bridge is composed of two 28-panel arch trusses; their heights vary from 18 m at the centre of the arch to 57 m at the ends next to the pylons. The arch has a span of 504m and its summit is 134m above the harbour surface. Large steel pins (or bearings) support each end of the arch, allowing it to expand and contract due changes of temperature, thus avoiding stress damage.

The total weight of the steelwork of the bridge, including the arch and approach spans, is 52,800 tonnes, with the arch itself weighing 39,000 tonnes. About 79% of the steel was imported from England, with the rest being sourced from Newcastle.

The bridge is held together by six million hand-driven rivets. The rivets were heated red-hot and inserted into the plates; the headless end was immediately rounded over with a large pneumatic rivet gun. The largest of the rivets used weighed 3.5 kg and was 39.5 cm long. The practice of riveting large steel structures, rather than welding, was, at the time a proven and preferred construction technique.

At each end of the arch stands a pair of 89 m high concrete pylons, faced with granite. Designed by Scottish architect Thomas S. Tait, the pylons were for decoration only.

Throughout construction some 250 Australian, Scottish, and Italian stonemasons and their families relocated to Moruya (south of Sydney), where they quarried around 18,000 m3 of granite for the bridge pylons. The stonemasons cut, dressed, and numbered the blocks, which were then transported to Sydney on three ships built specifically for this purpose.

Abutments at the base of the pylons support the loads from the arch and hold its span firmly in place. The pylons themselves have no structural purpose, and were included to ‘frame’ the arch panels and provide visual balance. However, all four pylons have now been put to use (the southeastern pylon contains a museum and tourist centre, the southwestern pylon is used by the New South Wales Roads and Maritime Services (RMS) to support CCTV cameras overlooking the bridge, and the two northern pylons include venting chimneys for fumes from the Sydney Harbour Tunnel.

There had been plans to build a bridge as early as 1815, when architect Francis Greenway reputedly proposed to Governor Lachlan Macquarie that a bridge be built from the northern to the southern shore of the harbour. Nothing came of Greenway's suggestions, but the idea remained alive, and many further suggestions were made during the nineteenth century.

In 1900, the Lyne state government organised a worldwide competition for the design and construction of a harbour bridge. Local engineer Norman Selfe won the competition, however, due to an economic downturn and a change of government at the 1904 NSW State election construction never began.

In 1914, J.J.C. Bradfield was appointed "Chief Engineer of Sydney Harbour Bridge and Metropolitan Railway Construction". Bradfield's initial preference was for a cantilever bridge and in 1916 the NSW Legislative Assembly passed a bill for construction. However, the project did not proceed due to World War 1.

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 a cantilever bridge and in 1921 he travelled overseas to investigate tenders. On his return Bradfield decided that an arch design might be more suitable and prepared a general design for a single-arch 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, and worldwide tenders were invited for the project.

On 24 March 1924, English firm Dorman Long and Co.Ltd was awarded the contract to build an arch bridge at a quoted price of AU£4,217,721 11s 10d. The arch design was cheaper than alternative cantilever and suspension bridge proposals, and was better suited for the heavy loads expected.

Bradfield and his staff were ultimately to oversee the entire bridge design and building process, while Dorman Long and Co's Consulting Engineer, Sir Ralph Freeman of Sir Douglas Fox and Partners, and his associate Mr. G.C. Imbault, carried out the detailed design and erection process of the bridge. Architects for the contractors were from the British firm John Burnet & Partners of Glasgow.

The building of the bridge coincided with the construction of a system of underground railways in Sydney's CBD, known today as the City Circle, and the bridge was designed with this in mind. 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 (city) side of the bridge by symmetrical ramps and tunnels. The eastern-side railway tracks were intended for use by a planned rail link to the Northern Beaches; in the interim they were used to carry trams from the North Shore to Wynyard station, and when tram services were discontinued in 1958, they were converted into extra traffic lanes.

The building of the bridge was under the management of Bradfield who worked on the bridge's design and construction with 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; 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 actually designed the bridge.

The official ceremony to mark the "turning of the first sod" occurred on 28 July 1923.

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. On Tuesday, 19 August 1930, (within two years) 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.

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 the 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 abutment 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. Gangers built the steelwork in the towers while day labourers manually cleaned the granite with wire brushes. The last stone of the northwest 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 standards of industrial safety during construction were poor by today's standards. Sixteen workers died during construction, 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 total cost of the bridge was AU£6.25 million, which was not paid off in full until 1988.

The bridge was formally opened on Saturday, 19 March 1932. Amongst those who attended and gave speeches were the State Governor, Sir Philip Game, the Minister for Public Works and Lawrence Ennis. The Labor Premier of New South Wales, Jack Lang, was to open the bridge by cutting a ribbon at its southern end.

However, just as Lang was about to cut the ribbon, a man in military uniform rode up on a horse, slashing the ribbon with his sword and opening the Sydney Harbour Bridge in the name of the people of New South Wales before the official ceremony began. He was promptly arrested. The ribbon was hurriedly retied and Lang performed the official opening ceremony. After he did so, there was a 21-gun salute and an RAAF fly-past. The intruder was identified as Francis de Groot who was later convicted of offensive behaviour and fined £5 after a psychiatric test proved he was sane - however, this verdict was reversed on appeal. De Groot then successfully sued the Commissioner of Police for wrongful arrest and was awarded an undisclosed out of court settlement. De Groot was a member of a right-wing paramilitary group called the New Guard who were opposed to Lang's leftist policies and resentful of the fact that a member of the Royal Family had not been asked to open the bridge. De Groot was not a member of the regular army but his uniform allowed him to blend in with the real cavalry. This incident was one of several involving Lang and the New Guard during that year.

A similar ribbon-cutting ceremony on the bridge's northern side by North Sydney's mayor, Alderman Primrose, was carried out without incident. It was later discovered that Primrose was also a New Guard member but his role in and knowledge of the de Groot incident, if any, are unclear. The pair of golden scissors used in the ribbon cutting ceremonies on both sides of the bridge was also used to cut the ribbon at the dedication of the Bayonne Bridge, which had opened in Bayonne, New Jersey close to New York City, the year before.

Despite the bridge opening in the midst of the Great Depression, opening celebrations were organised by the Citizens of Sydney Organising Committee, an influential body of prominent men and politicians that formed in 1931 under the chairmanship of the Lord Mayor to oversee the festivities. The celebrations included an array of decorated floats a procession of passenger ships sailing below the bridge, and a Venetian Carnival. A message from a primary school in Tottenham, 515 km away in rural New South Wales, arrived at the bridge on the day and was presented at the opening ceremony. It had been carried all the way from Tottenham to the bridge by relays of school children, with the final relay being run by two children from the nearby Fort Street Boys' and Girls' schools. The City of Sydney organising Committee also announced plans for a Great Eisteddfod. Lord Mayor Samuel Walder told the press that the competition would begin at the Town Hall in August 1933 and thus began the Sydney Eisteddfod.

After the official ceremonies, the public was allowed to walk across the bridge on the deck, something that would not be repeated until the 50th anniversary celebrations. Estimates suggest that between 300,000 and one million people took part in the opening festivities, a phenomenal number given that the entire population of Sydney at the time was only a little over a million people.

On 14 March 1932, three postage stamps were issued to commemorate the imminent opening of the bridge and several songs were composed for the occasion.

The bridge itself was regarded as a triumph over Depression times, earning the nickname "the Iron Lung", as it kept many Depression-era workers employed.

This project couldn't have happened without the support from the following organisations