Sydney Harbour Bridge connects Sydney central business district (CBD) and the North Shore across the Sydney Harbor. It was designed by British firm Dorman Long and Co Ltd of Middlesbrough. It is completed in 1932.
Since 1815, there were ideas to build the bridge in the Sydney Harbor. Because of different reasons (economic, politic and design) it took some 100 years for ideas to bear fruit. J.J.C. Bradfield, "Chief Engineer of Sydney Harbour Bridge and Metropolitan Railway Construction" since 1912, liked the idea that a future Sydney Harbour Bridge should be cantilever bridge and in 1916, NSW Legislative Assembly approved such a construction but Legislative Council disagreed because it was of opinion that money should go into war effort.
After the World War I, bridge again looked like a good idea and Bradfield 1921 traveled abroad to investigate tenders. When he returned, he brought with himself another idea - arch design could work too.
He and officers of the NSW Department of Public Works based their general design on Hell Gate Bridge from New York City. On 24 March 1924 contract was awarded to English firm Dorman Long and Co Ltd, of Middlesbrough because they already had similar experience with arch Tyne Bridge that they built.
Arch bridge was chosen because it was cheaper and stronger than other proposed solutions. Building of the bridge happened roughly at the same time as construction of the underground railway system in Sydney so the bridge was conceived in a way that it can accommodate railway traffic too.
Bridge was designed to have six lanes for road traffic, two for railroad and one for pedestrian.