THE SYDNEY HARBOUR BRIDGE

LOCATION: In the Rocks area of Sydney, stretching from Dawes Point, to Milsons Point across Sydney Harbour.

The Sydney Harbour Bridge was finished on Saturday 19th March 1932 and opened by the Premier, Jack Lang. There was a brief incident when a man on horseback slashed the official tape before the Premier could cut it.

Sydney Harbour Bridge is the world's largest (but not longest) steel arch bridge, and has become a renowned international symbol of Australia.

Its total length including approach spans is 1149 metres and its arch span is 503 metres. The top of the arch is 134 metres above sea level and the clearance for shipping under the deck is a spacious 49 metres. The total steelwork weighs 52,800 tonnes, including 39,000 tonnes in the arch. The 49 metre wide deck makes Sydney Harbour Bridge the widest Longspan Bridge in the world.

It now carries eight vehicle lanes, two train lines, a footway and a cycleway.

The Sydney Harbour Bridge is one of Sydney's most famous landmarks. The construction of the bridge was an economic feat as well as an engineering triumph. Before the bridge was built, the only links between the city centre in the south and the residential north were by ferry or by a 20 kilometre (12 mile) road route that involved five bridge crossings.

Construction on the bridge began in December, 1926. The foundations, which are 12 metres (39 feet) deep, are set in sandstone. Anchoring tunnels are 36 metres (118 feet) long and dug into rock at each end. Construction on the arch began in November, 1929. It was built in halves with steel cable restraints initially supporting each side. The arch spans 503 metres (1650 feet) and supports the weight of the bridge decking, with hinges at either end bearing the bridge's full weight and spreading the load to the foundations. The hinges allow the structure to move as the steel expands and contracts in response to changes in temperatures and wind.

Each half arch was built out from either side of the harbour, using a creeper crane with a lifting capacity of 122 tonnes, which travelled on the top chords of the arch. The half arches were secured by wire ropes, anchored in inclined U-shaped tunnels cut into the rock well behind the springings. Each anchorage consisted of 128 wire ropes of 70 mm diameter, about 366 m long. The steelwork from the fabricating shops was brought under the creeper cranes on barges.

By October, 1930, the two arch halves had met and work then began on the deck. The deck is 59 metres (194 feet) above sea level and was built from the centre out.

When the Harbour Bridge was opened, the initial toll for a car was 6 pence (5 cents) and a horse and rider was 3 pence (2 cents). The annual maintenance costs are approximately $5 million. More than 150,000 vehicles cross the bridge each day.

The bridge was built by 1400 workers, 16 of whom were killed in accidents during construction. Painting the bridge has become an endless task. Approximately 80,000 litres (21,000 gallons) of paint are required for each coat, enough to cover an area equivalent to 60 soccer fields. Before Paul Hogan (from the movie Crocodile Dundee) became famous, he worked on the Sydney Harbour Bridge as a painter.

The Pylon Lookout is recommended for visitors, giving wonderful views of the harbour. Inside the Lookout is a fascinating display on how this bridge was built. Entry to the Pylon is from the pedestrian walkway on the Harbour Bridge. You can get to the walkway via the stairs in Cumberland Street, The Rocks, or from near Milsons Point Station on the north side. The Pylon Lookout is open every day except Christmas Day.