Heavy Lifter: Spreader Beam Lifting Rig for Bridge Project

Amey, on behalf of Transport Scotland, undertakes services associated with the operation, management and maintenance of the Forth Road Bridge and its approach roads. It carried out overnight repairs on the bridge last month (December). Rope and Sling provided a spreader beam lifting rig to lift a 35t Bronto Skylift (a mobile elevating work platform or MEWP) provided by Nationwide Platforms.

Access was required to make a repair to a support truss on the bridge’s northern pier. The pier from the north tower is sited on the Mackintosh Rock, a whinstone outcrop that made for an ideal foundation during construction.

Rope and Sling hired to the project a modular spreader beam type MOD70H with two MOD34 beams, manufactured by Modulift, with various round slings and shackles from its hire stock. The rig was assembled in line with computer-aided design (CAD) drawings of the MEWP, sent to Rope and Sling by Nationwide Platforms.

The lifting rig was used below the hook of a barge crane—the bridge spans the Firth of Forth—that lifted the truck-mounted hydraulic platform onto the barge from the shore, travelled to the site, then lifted it to the base of the bridge from where it would lift personnel, stabilised by outriggers. Upon completion of the work, the rig was employed again to return the MEWP to the barge, remove it from the scene by water and return it to shore.

“We only had half a day to design the assembly of the rig and deliver it to the site but we were able to use CAD drawings from Nationwide to calculate the centre of gravity—the load was heavier at one end—and we knew we could use the outriggers as pick up points,” said Steve Hutin, MD, Rope and Sling Specialists. “The main towers of the Forth Road Bridge rise up over 150m above high water level. It is an impressive feat of engineering; the bridge has a main span of over 1,000m between the two main towers and the side spans that carry the deck to the towers are each over 400m long,” he said.