During routine inspections of the Forth Road Bridge in 2015, a crack in the pivot of one of the truss end links was discovered. The changeout of the affected steelwork initially took 18 months to complete; largely slowed down by the traditional scaffolding having to be continually modified to react to the changing work scope and with the scaffolders impeded with a lack of suitable steelwork for their connections into the structure.
Subsequently in 2017, Transport Scotland decided to change the remaining seven end links as a precaution. Due to the disappointing results using conventional access methods, Span Access – now a HAKI Group company – was contracted to design, engineer, and install a bespoke access system for the later works.
A completely unique hybrid solution using the TechniSpan suspended access platform was specified, which was easily capable of spanning the 10m between structural pick-ups while retaining the strength required to support a five-lift scaffold in its entirety. This in turn was mated with a compatible HAKI Stair Tower, constructed from the platform deck level; giving the contractors five working lifts to access all areas of the scaffold.
Several scenario drawings and checks were completed by the in-house design team, prior to installation, to allow the platform to be opened-up and allow the lifting in of steelwork from river level. A host of hop-ups and variations on the five-lift scaffold were also all designed and checked in advance to give the project the flexibility it needed to succeed.
Additional engineering support throughout the project allowed the client to react to unforeseen circumstances and the swift removal of the system allowed normal bridge operations to resume earlier than planned.
Together, Span Access, the TechniSpan system and HAKI, helped achieve an 80% reduction in installation time over traditional scaffolding. This led to successful delivery of the project, along with the additional pre-mobilisation engineering works which allowed for most modifications to be completed without works being halted.