The Sydney Harbour Bridge is a steel through arch bridge across Sydney Harbour that carries rail, vehicular, bicycle, and pedestrian traffic between the Sydney central business district (CBD) and the North Shore. The dramatic view of the bridge, the harbour, and the nearby Sydney Opera House is an iconic image of Sydney, and Australia. The bridge is nicknamed "The Coathanger" because of its arch-based design or is simply called "the Bridge" by Sydney residents.
Under the direction of Dr J.J.C. Bradfield of the NSW Department of Public Works, the bridge was designed and built by British firm Dorman Long and Co Ltd of Middlesbrough and opened in 1932 The bridge's design was influenced by the Hell Gate Bridge in New York City. It is the sixth longest spanning-arch bridge in the world and the tallest steel arch bridge, measuring 134 m (440 ft) from top to water level.It was also the world's widest long-span bridge, at 48.8 m (160 ft) wide, until construction of the new Port Mann Bridge in Vancouver was completed in 2012
The southern (CBD) end of the bridge is located at Millers Point in The Rocks area, and the northern end at Milsons Point in the lower North Shore area. There are six original lanes of road traffic through the main roadway, plus an additional two lanes of road traffic on its eastern side, using lanes that were formerly tram tracks. Adjacent to the road traffic, a path for pedestrian use runs along the eastern side of the bridge, whilst a dedicated path for bicycle use only runs along the western side. Finally, between the main roadway and the western bicycle path are two lanes used for railway tracks, servicing the T1 North Shore Line for Sydney Trains.
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.
There had been plans to build a bridge as early as 1815, when convict and noted architect Francis Greenway reputedly proposed to Governor Lachlan Macquarie that a bridge be built from the northern to the southern shore of the harbour. In 1825, Greenway wrote a letter to the then "The Australian" newspaper stating that such a bridge would "give an idea of strength and magnificence that would reflect credit and glory on the colony and the Mother Country".
Nothing came of Greenway's suggestions, but the idea remained alive, and many further suggestions were made during the nineteenth century. In 1840, naval architect Robert Brindley proposed that a floating bridge be built. Engineer Peter Henderson produced one of the earliest known drawings of a bridge across the harbour around 1857. A suggestion for a truss bridge was made in 1879, and in 1880 a high-level bridge estimated at $850,000 was proposed.
In 1914 J.J.C. Bradfield was appointed "Chief Engineer of Sydney Harbour Bridge and Metropolitan Railway Construction", and his work on the project over many years earned him the legacy as the "father" of the bridge.Bradfield's preference at the time was for a cantilever bridge without piers, and in 1916 the NSW Legislative Assembly passed a bill for such a construction, however it did not proceed as the Legislative Council rejected the legislation on the basis that the money would be better spent on the war effort.