The Sydney Harbour Bridge is localized in Sydney, Astrualia. Is an arch bridge across Sydney Harbour that carries rail, vehicular, and pedestrian traffic between the Sydney central business district (CBD) and the North Shore. Made of steel the bridge contains 6 million hand driven rivets. The surface area that requires painting is equal to about the surface area of 60 sports fields. The Bridge has huge hinges to absorb the expansion caused by the hot Sydney sun. The dramatic view of the bridge, the harbour, and the nearby Sydney Opera House is an iconic image of both Sydney and Australia. The bridge is locally nicknamed The Coathanger because of its arch-based design, although this usage is less prevalent than it once was.
The purpose of the Sydney Harbour Bridge was connect the northern to the southern shore of the harbour.
The Sydney Harbour Bridge was the city's tallest structure until 1967. It is the world's largest (but not the longest) steel arch bridge with the top of the bridge standing 134 metres above the harbour.
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.
Bridge structure
The bridge's ends are located at Teds Point and Milsons Point. 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 road across the bridge is known as the Bradfield Highway, Sydney, and is about 2.4 km (1.5 miles) long, making it one of the shortest highways in Australia.
Deck
At 48.8 m (151.3 ft) wide, it is the widest long-span bridge in the world.
The bridge deck portion of the highway is 1.15 km (0.71 miles) 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 bridge. The trimmers and beams are visible to boats and people that pass underneath the bridge.
Arch
The arch is composed of two 28-panel arch trusses. Their heights vary from 18 m (55.8 ft) at the center of the arch to 57 m (176.7 ft) (beside the pylons).
The arch span is 300 m (1,650 ft) and the weight of the steel arch is 39,000 tons. The arch's summit is 134 m (440 ft) above mean sea level, though it can increase by as much as 180 mm (7 in) 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. The steel used for the bridge was largely imported. The total weight of the bridge is 52,800 tonnes, and six million hand-driven rivets hold the bridge together.
Pylons
The two pairs of pylons at each end are about 89 m (276 ft) high and are made of concrete and granite. 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 originally not part of the design but were added later to allay concerns about structural integrity — ironically, as the pylons do not actually touch the bridge (except at road level).
Although inserted into the designs 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 (two trucks and safety vehicles used on the bridge) is contained in the bottom of the northern pylon.
The principal advantage of built the Sydney Harbour Bridge is that it became an essential artery feeding traffic to and from Sydney.
Some interesting facts about the Bridge
Length of arch span 503 metres
Height of top of arch 134 metres above mean sea level
Height to top of aircraft beacon 141 metres above mean sea level
Width of deck 49 metres
Clearance for shipping 49 metres
Height of pylons 89 metres above mean sea level
Base of each abutment tower 68 metres across and 48 metres long (two pylons rest on each abutment tower)
Total length of bridge 1149 metres including approach spans
Bearing pins Each of the four pins measures 4.2 metres long and 368 millimetres in diameter
Thrust on bearings Under maximum load approximately 20,000 tonnes on each bearing
Number of rivets Approximately 6,000,000
Largest rivet Weighed 3.5 kilograms and was 395 millimetres long
Longest hanger 58.8 metres
Shortest hanger 7.3 metres
Total weight of steelwork 52,800 tonnes including arch and mild steel approach spans
Weight of arch 39,000 tonnes
Rock excavated for foundations 122,000 cubic metres
Concrete used for bridge 95,000 cubic metres
Granite facing used on pylons and piers 17,000 cubic metres
Allowance for deck expansion 420 millimetres
Allowance for arch expansion The arch may rise or fall 18 centimetres due to heating or cooling
Number of panels in arch 28, each 18.28 metres wide
Record tonnage erected 589 tonnes of steelwork was erected on the arch in one day on 26 November 1929
Paint required 272,000 litres of paint were required to give the Bridge its initial three coats
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