The foundation stone for the new bridge was laid on 6 December 1899 by E. W. O'Sullivan and the bridge was opened for traffic on 28 June 1902 by the
Governor of New South Wales,
Harry Rawson. The bridge was designed under the engineering supervision of
Percy Allan. The bridge had one of the largest swing spans in the world at the time of its construction and it was one of the first to be powered by electricity. Allan also designed the similar
Glebe Island Swing Bridge, completed in 1903. The Pyrmont Bridge is long and cost
£112,500 to build. The bridge is made up of 14 spans with Australian
ironbark timber used on 12 spans, while the two central spans, which swing, are constructed from
steel. The swingspan weighs and is supported on a base made from concrete and
Hawkesbury Sandstone. The base is filled with mass concrete and weighs . The swingspan is in diameter and deep. The water is deep and the base extends a further below the sea floor. The bridge was closed to vehicular traffic on 7 August 1981, In 1992
Engineers Australia recognised the bridge as a National Engineering Landmark.
Modifications As built, the bridge had stone abutments on both ends, the western end connecting it to Union Street and the eastern end connecting it to Market Street. In 1980, most of the eastern abutment was demolished as part of the construction of the Western Distributor. A section connected to the bridge remains, and the isolated easternmost plinth and lamppost can still be seen near the corner of Market Street and Sussex Street. In 1980, the eastern end of the bridge was initially connected via a ramp to the viaduct leading north to King Street, but this was demolished in 1981 when the rest of the viaduct was completed around the southern end of Cockle Bay. Only a narrow pedestrian and cycle path still connects the eastern end of the bridge to the viaduct and to King Street. A separate pedestrian bridge was constructed over the Western Distributor roadway to connect the eastern end of the bridge to Market Street at surface level. Between 1988 and 2013, the bridge carried the elevated
Sydney Monorail, which travelled between Darling Harbour and the Sydney central business district. The monorail track rested on a pivot that allowed the track to remain stationary while the bridge swung underneath. The pivot allowed the monorail to continue to cross the bridge even when the bridge was opened. The construction of the monorail led to some changes to the bridge, including the electrification of the previously hand-operated brakes used to control the bridge's swing, and the relocation of the control cab six metres away from the middle of the bridge (so that the control cab would not hit the monorail track when the bridge is open). Upon the closure of the Monorail in June 2013 the hydraulic lifting rams and support infrastructure were removed, and the control cab was relocated to its original position in the middle of the bridge. == Heritage listing ==