TechiSpan speeds up Forth Road Bridge steelwork changeout

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.

Completely unique hybrid solution

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. 

A number of possibilities and variations

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. 

Project results:

  • 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.