Sydney Harbour Bridge, steel-arch bridge across Sydney Harbour (Port Jackson), Australia. The bridge, opened in 1932, serves as the primary transportation link between Sydney and its suburbs on the northern side of the harbour. It spans about 500 metres (1,650 feet), making it one of the longest steel-arch bridges in the world. Along its length, it features four railroad tracks, a highway, and two pedestrian walkways.
In 1912 John Bradfield, a civil engineer with the New South Wales Department of Public Works, presented plans to Australia’s parliament for the construction of a bridge over Sydney Harbour, with options for either a suspension bridge or a cantilever bridge design. He envisioned the structure as part of an electric railway system for Sydney and its suburbs. The year after Bradfield submitted his plans, his cantilever design was accepted, and he was appointed to lead the project. Work on the bridge was delayed by World War I, however, and it was not until 1922, with the passage of the Sydney Harbour Bridge Act, that funding for the project became available. By that time too, progress in steelmaking had made possible the construction of an arch bridge.
The building contract was awarded to the English enterprise Dorman Long & Co., which hired Sir Ralph Freeman to perform detailed design work. The final, approved plan called for a steel-arch bridge linking Dawes Point on the south with Milsons Point on the north. An arch bridge was chosen because it was less expensive than a cantilever design and capable of handling heavier loads. Construction began in 1924 under Bradfield’s supervision. The deep waters of Sydney Harbour made temporary supports impractical, so the steel arch was assembled by building out from each bank. The two sides met in the middle in 1930, and the bridge was officially opened with an elaborate ceremony on March 19, 1932.
Despite Bradfield’s submission of proposals for the bridge design, Freeman considered himself to be the bridge’s true designer. The claim was supported by some authorities, though the controversy was never fully resolved.