The Swing Bridge is a swing bridge over the River Tyne, England connecting Newcastle upon Tyne and Gateshead, and lies between the Tyne Bridge and the High Level Bridge. The hydraulic power to move the bridge is derived from electrically driven pumps. This feeds a hydraulic accumulator sunk into a 60 feet (18 m) shaft below the bridge, the water is then released under pressure which runs the machinery to turn the bridge. The mechanism used for this is still the same machinery originally installed by Armstrong. It has an 281 feet (85.6 m) cantilevered span with a central axis of rotation able to move through 360° to allow vessels to pass on either side of it. The previous bridge on the site was demolished in 1868 to enable larger ships to move upstream to William Armstrong's works. The hydraulic Swing Bridge was designed and paid for by Armstrong, with work beginning in 1873. It was first used for road traffic on 15 June 1876 and opened for river traffic on 17 July 1876. The Swing Bridge stands on the site of the Old Tyne Bridges of 1270 and 1781, and probably of the Roman Pons Aelius.