The project required the removal of 38 defective existing steel collars, comprising heavy section steel channels and tie bars. As each of the old collars were removed, new ones were reinstated on a sequential basis. This accommodated load transfers to the structure, which was monitored constantly by the use of strain gauges.
The project presented numerous problems; the shear height of the rail viaduct, the steep sided gorge and needing to keep the train line open during the works.
CAN designed bespoke trolleys to facilitate the transportation of the old and new sets of collars along the underdeck of the bridge.
Contributing to the design of the collars, CAN introduced lifting points to make rigging easier when lowering them from the walkway.
Duration: 7 weeks
Client: Birse Rail