ENSURING that track on seven viaducts does not move because of ground settlement was one of many challenges facing engineers designing Hong Kong MTR’s airport line, now due to open on July 6. The answer was to use Hydratight’s lifting and jacking equipment controlled by a lift management system. An arrangement of jacks allows movement in the transverse or horizontal plane.

Cable and hydraulic runs are installed permanently in the hollow viaduct girders. When required, portable hydraulic jacks, valves and hoses married to electronic displacement units are positioned at each pier and connected to the ring mains. After realignment, installation of mechanical jacks locks the viaduct in the new position.

The lift management system includes computer equipment with a laptop PC to control the jacks to a pre-set displacement limit as demanded by the specification. A full realignment test including locking of the mechanical jacks and 20mm of horizontal movement took just 2h, well within the 3h specification demanded by main contractor GTM.

Hydratight, Great Britain

Reader Enquiry Number 143