The Sydney Harbour Bridge

The Harbour Bridge is Sydney is another place of tourists’ attraction. The Harbour Bridge is a steel through arch bridge in Sydney, spanning Sydney Harbour from the central business district Centre to the North Shore. The view of the bridge, the Harbour, and the nearby Sydney Opera House is widely regarded as an iconic image of Sydney, and of Australia itself. Nicknamed "the Coathanger" because of its arch-based design, the bridge carries rail, vehicular, and pedestrian traffic. The bridge was designed and built by British firm Dorman Long of Middlesbrough, and opened in 1932. It is the tenth-longest spanning-arch bridge in the world and the tallest steel arch bridge, measuring 134 mitre (440 ft) from top to water level. It was also the world's widest long-span bridge, at 48.8 mitre (160 ft) wide. Now the new Port Mann Bridge in Vancouver in Canada, which was completed in 2012, has broken the Sydney Harbour Bridge's tenth place. The main roadway across the bridge is known as the Bradfield Highway and is about 2.4 km (1.5 mi) long, making it one of the shortest highways in Australia.

The arch is composed of two 28-panel arch trusses; their heights vary from 18 m (59 ft) at the centre of the arch, to 57 m (187 ft) at the ends next to the pylons. The arch has a span of 504 m (1,654 ft), and its summit is 134 m (440 ft) above mean sea level; expansion of the steel structure on hot days can increase the height of the arch by 18 cm (7.1 inches). 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. As per records, about 79% of the steel was imported pre-formed from England. The bridge is held together by six million Australian-made hand-driven rivets supplied by the McPherson company of Melbourne, the last being driven through the deck on 21 January 1932. The practice of riveting large steel structures, rather than welding was a proven construction technique, whilst structural welding had not at that stage been adequately developed for use on the bridge.

At each end of the arch stands a pair of 89-metre-high (292 ft) concrete pylons, faced with granite. The pylons were designed by the Scottish architect Thomas S. Tait. About 250 Australian, Scottish, and Italian stonemasons and their families relocated to a temporary settlement at Moruya, 300 km south of Sydney, where they quarried around 18,000 metric (635,664 cu ft) of granite for the bridge pylons. Abutments at the base of the pylons are essential to support the loads from the arch and hold its span firmly in place, The pylons were not part of the original design, and were only added to allay public concern about the structural integrity of the bridge. The available information says that in 1942, the pylons were modified to include parapets and anti-aircraft guns designed to assist in both Australia's defence and general war effort. The bridge was formally opened on 19 March 1932.In 1958 tram services across the bridge were withdrawn and the tracks replaced by two extra road lanes. 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.The bridge was formally opened on 19 March 1932.The bridge is equipped for tidal flow operation, permitting the direction of traffic flow on the bridge to be altered to better suit the morning and evening peak hour traffic patterns. The bridge has eight lanes, numbered one to eight from west to east. Lanes three, four and five are reversible. The bridge lies between Milsons Point and Wynyard railway stations, located on the north and south shores respectively, with two tracks running along the western side of the bridge. These tracks are part of the North Shore railway line.

The Harbour Bridge has been an integral part of the Sydney New Year's Eve celebrations, generally being used in spectacular ways during the fireworks displays at midnight. In recent times, the bridge has included a ropelight display on a framework in the centre of the eastern arch, which is used to complement the fireworks. The scaffolding and framework were clearly visible for some weeks before the event, revealing the outline of the design.