<P> The building of the bridge coincided with the construction of a system of underground railways in Sydney's CBD, known today as the City Circle, and the bridge was designed with this in mind . The bridge was designed to carry six lanes of road traffic, flanked on each side by two railway tracks and a footpath . Both sets of rail tracks were linked into the underground Wynyard railway station on the south (city) side of the bridge by symmetrical ramps and tunnels . The eastern - side railway tracks were intended for use by a planned rail link to the Northern Beaches; in the interim they were used to carry trams from the North Shore into a terminal within Wynyard station, and when tram services were discontinued in 1958, they were converted into extra traffic lanes . The Bradfield Highway, which is the main roadway section of the bridge and its approaches, is named in honour of Bradfield's contribution to the bridge . </P> <P> The building of the bridge was under the management of Bradfield . Three other people heavily involved in the bridge's design and construction were Lawrence Ennis, Edward Judge, and Sir Ralph Freeman . Ennis was the engineer - in - charge at Dorman Long and Co and the main on - site supervisor (Bradfield visited occasionally throughout the project and, in particular, at many key stages of the project, to inspect progress and make managerial decisions), Judge was chief technical engineer of Dorman Long, and Freeman was hired by the company to design the accepted model in further detail . Later a bitter disagreement broke out between Bradfield and Freeman as to who actually designed the bridge . </P> <P> The official ceremony to mark the "turning of the first sod" occurred on 28 July 1923, on the spot at Milsons Point on the north shore where two workshops to assist in building the bridge were to be constructed . </P> <P> An estimated 469 buildings on the north shore, both private homes and commercial operations, were demolished to allow construction to proceed, with little or no compensation being paid . Work on the bridge itself commenced with the construction of approaches and approach spans, and by September 1926 concrete piers to support the approach spans were in place on each side of the harbour . </P>

When did construction start on the sydney harbour bridge