Sydney Harbour Bridge
Official name Sydney Harbour Bridge
Carries Trains, Motor vehicles, pedestrians and bicycles
Crosses Port Jackson
Locale Sydney, Australia
Longest span 503 metres
Total length 1149 metres
Width 49 metres
Height 139 metres
Clearance below 49 metres at mid-span
Beginning date of construction 28 July 1923
Completion date 19 January 1932
Opening date 19 March 1932
The bridge was designed and built by Dorman Long and Co Ltd, Middlesbrough Teesside and Cleveland Bridge, Darlington, County Durham and opened in 1932. Until 1967 it was the city's tallest structure. According to Guinness World Records, it is the world's widest long-span bridge and it is tallest steel arch bridge, measuring 134 metres from top to water level. It is also the fourth-longest spanning-arch bridge in the world.
The southern (CBD) bridge end is located at Millers Point in The Rocks area, and the northern end at Milsons Point in the lower North Shore area. It carries six lanes of road traffic on its main roadway, two lanes of road traffic (formerly two tram tracks) and a footpath on its eastern side, and two railway tracks and a bicycle path along its western side, being 305 mm larger than the east side.
The main roadway across the bridge is known as Bradfield Highway, Sydney, and is about 2.4 km long, making it one of the shortest highways in Australia. (The shortest, also called the Bradfield Highway, is found on the Story Bridge in Brisbane). The Sydney Harbour Bridge is not completely stationary. It can rise or fall up to 18 cm depending on whether it is hot or cold due to the steel expanding or contracting.
At 48.8 m wide, it is the widest long-span bridge in the world (Guinness World Records, 2004). The bridge deck portion of the highway is 1.16 km long. It is concrete and lies on trimmers (beams that run along the length of the bridge). The trimmers themselves rest on steel beams that run along the width of the ridge.
The arch is composed of two 28-panel arch trusses. Their heights vary from 18 m at the centre of the arch to 57 m (beside the pylons). The arch span is 503 m and the weight of the steel arch is 39,000 tons. The arch's summit is 134 m above mean sea level, though it can increase by as much as 180 mm on hot days as the result of steel expanding in heat. Two large metal hinges at the base of the bridge accommodate these expansions and contractions and thereby prevent the arch from being damaged. About 79% of the steel came from Middlesbrough, in the North East of England. The rest was Australian-made. The total weight of the bridge is 52,800 tonnes, and six million hand-driven rivets hold the bridge together. The rivets were made at the Park Bridge Ironworks in Lancashire England.
At each end of the bridge stands a pair of 89 m high concrete and granite pylons. The pylons were designed by the Scottish architect Thomas S Tait a partner in the architects' firm John Burnet & Partners. The granite was quarried at Moruya, New South Wales, 250 km south of Sydney. The concrete used was also Australian made. Abutments, which support the ends of the bridge, are contained at the base of the pylons. They prevent the bridge from stretching or compressing due to temperature variations. Otherwise, the pylons serve no structural purpose and are primarily to visually balance the bridge itself. They were never an essential part of the design but were added to allay concerns about structural integrity. Although inserted into the design for their aesthetic value, all four pylons have now been put to use: a museum and tourist centre with a lookout of the harbour is contained in the south eastern pylon. The south western pylon is used by the New South Wales Roads and Traffic Authority (RTA) as a base for their CCTV cameras overlooking the bridge and the roads around that area. The two pylons on the north shore are now venting chimneys for fumes from the Sydney Harbour Tunnel. The RTA maintenance shed for the bridge is contained within the bottom of the southern pylon and the traffic management shed (tow trucks and safety vehicles used on the bridge) is contained in the bottom of the northern pylon. On New Year's Eve, the numbers for the countdown appear on the pylons of the bridge.
History Early proposals
There had been plans to build a bridge as early as 1815, when Francis Greenway proposed that a bridge be built across the harbour. Nothing came of this. By 1900, a competition was launched to find a suitable design. There were many entries, but none were accepted due to low standards.
Designs and proposals were requested in 1900, but a formal proposal was not accepted until 1911. In 1912, John Bradfield, with his assisstant Daniel Newlan, was appointed chief engineer of the bridge project, which also had to include a railway. After travelling extensively to look at a number of bridges worldwide, he based his idea upon New York City's Hell Gate Bridge. Bradfield completed a formal design for a single arch bridge in 1916, but plans to implement the design were postponed until 1922, primarily because of World War I. Serious initiatives started after the end of World War I. In November 1922 the New South Wales parliament passed laws that allowed the bridge's construction. Construction tenders for the bridge were requested the same year. Either an arch or a cantilever bridge would meet the requirements. Dr J. J. C. Bradfield was responsible for setting the parameters of the tendering process. The British firm Dorman Long and Co Ltd, of Middlesbrough, won. To offset concerns about a foreign firm participating in the project, assurances were given by Bradfield that the workforce building the bridge would all be Australians. Dorman Long and Co's Consulting Engineer, Sir Ralph Freeman, carried out the detailed design of the bridge. Bradfield and his staff were to ultimately oversee the entire bridge design and building process. Architects for the contractors was the British firm John Burnet & Partners of Glasgow, Scotland. 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 by two railway tracks and a footpath on each side. Both sets of rail tracks were linked into the underground Wynyard railway station, on the south 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 to be used to carry trams from the North Shore into a terminal within Wynyard station. The Bradfield Highway, which is the paved section of the bridge and its approaches, and is the shortest highway in Australia, still bears Bradfield's name to this day.
In 1923, 800 homes and a high school campus were demolished in preparation for construction. The owners of these homes received compensation, but their occupants did not. The building of the bridge was under the management of Bradfield. Three other people were involved in the bridge's design and construction: Laurence Ennis, the engineer-in-charge at Dorman Long and Co was the main supervisor (Bradfield visited occasionally throughout the project and, in particular, at the many key stages of the project, to inspect progress and make managerial decisions); Edward Judge was chief technical engineer of Dorman Long and later became president of the British Iron and Steel Federation; Sir Ralph 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. Another name connected with the bridge's design is that of Arthur Plunkett. The official ceremony to mark the "turning of the first sod" occurred on 28 July 1923. This was followed by the building of two worksheds at Milsons Point to assist in building the bridge—the light and heavy workshops. Their purpose was to build the bridge's many parts. In January 1925, the excavations to build the abutments and approach spans began. In October 1925, the building of the abutments and approach spans themselves began, and these were completed in September 1928. Construction of the bridge itself began in December 1928, with the construction of the bridge parts in the workshops. Construction of the arch of the bridge began in 1929, with two separate teams building the arch on each side using creeper cranes. The first panel was erected on the southern side in March 1929. The southern end of the bridge was worked on a month ahead of the northern end, in order to detect any errors and to ensure that they did not happen on the northern side. During construction, the two halves of the arch were held up by numerous support cables. Once the arch halves were completed the cables were slowly released to bring the two halves of the arch together. This was finalised on the afternoon of 19 August 1930. Ennis and four associates personally witnessed this whilst standing on top of the bridge. Following a parting that occurred due to the contraction of metal in the evening, the ends were rejoined at 10 pm, and have remained joined since then. The support cables were then surplus to the design and removed. They were subsequently used as support cables for the Walter Taylor Bridge, over the Brisbane River in the western suburbs of Brisbane, Queensland. The road and the two sets of tram and railway tracks were completed in 1931. Power and telephone lines, and water, gas and drainage pipes were also all added to the bridge in that year. On 19 January 1932, the first test train, a steam locomotive, safely crossed the bridge. About 90 others also crossed the bridge in the months that followed as part of a series of tests to ensure the bridge's safety. The construction worksheds were demolished after the bridge was completed, and the land that they were on is now occupied by Luna Park and the North Sydney Swimming Pool. 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 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 $10 million (double the original quote). This was not paid off in full until 1988.
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