Paddington bridge on a roll

Paddington Basin’s unique rolling bridge is “a work of art that happens to be a bridge”, according to the project’s structural engineer.

The 12.9m pedestrian bridge, conceived by designer Thomas Heatherwick, which spans an 8.5m canal inlet and is made up of eight segments which lift and roll back under hydraulic power to form a circle, as shown in this composite photo.

Alan Jones, Project Director for structural engineer SKM Anthony Hunts, said the structural design presented unusual challenges because of the constantly changing geometry.

The structural frame is fabri-cated in grade S355 rectangular hollow section, to fine tolerances more usually associated with mechanical engineering than construction.

The bridge is stable in the open and fully closed positions without the aid of hydraulics. In its unrolled position it behaves as a truss with the handrails acting as the top boom.

As the lift begins the structure changes from a simply supported to a cantilevered truss, with the consequent load reversal. Several segments undergo a second load reversal as they roll over the centre of the circle. It is opened every Friday at 12 noon.