The swinging action allows large vessels using the ship canal to pass through and smaller craft, both narrowboats and broad-beam barges, to cross over the top.

[2][3] Designed by Sir Edward Leader Williams and built by Andrew Handyside and Company of Derby, the swing bridge opened in 1894 and remains in regular use.

The scale of the operation meant that the course of the River Irwell had to be temporarily diverted around the site, so that the central island could be built on dry land.

When large vessels need to pass along the ship canal underneath, the 1,450-tonne (1,430-long-ton; 1,600-short-ton)[3] and 330-foot (100 m) long iron trough[5] is rotated 90 degrees on a pivot mounted on a small purpose-built island.

[6][10] To avoid the risk of collision, the aqueduct is opened half an hour before traffic on the Manchester Ship Canal is scheduled to pass.

Sixty-four tapered cast iron rollers sat on top of the race plate, held in position by a spider ring.

On top of that an upper race plate supports the aqueduct and its circular gear rack, which was powered by a hydraulic engine manufactured by Sir W. G. Armstrong Mitchell of Newcastle.