During routine inspections of the Forth Road Bridge by the operator, a crack in the pivot of one of the truss end links was discovered in late December 2015. This resulted in the bridge, one of the main transport links in the area being closed over the festive period and lengthy diversions.
The changeout of the affected steelwork 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.
Roll into 2017 and Transport Scotland decided to change the remaining seven end links as a precaution. The Spencer Group were awarded the contract, and they contracted Span Access to design, engineer and install a bespoke access system for their project.
A flexible, quick to install suspended access solution comprising of a platform to the underside of the location, a scaffold around the steelwork to be replaced and personnel access to both structures.
The system was required to be designed and engineered by Span, put through a Cat III check by us before a separate check by the operators chosen internal engineers and choice of Cat III checker.
Span specified a completely unique hybrid solution, the kind of which we are sure has never been attempted before, certainly not, at least, in the UK. A TechniSpan 750 suspended access platform was designed as it’s easily capable of spanning the 10m between structural pick-ups while retaining the strength required to support a five-lift scaffold in its entirety from the platform in addition to personnel and wind loads experienced in such an extreme environment. No other suspended access platform from within our portfolio
has the capacity to bear such high loads. This in turn was mated with a compatible bay sized HAKI Universal scaffold constructed from the platform deck level and giving the contractors five working lifts to access all areas of the scaffold.
A number of scenario drawings and checks were completed prior to installation to allow the platform to be opened up and allow the lifting in of steelwork from river level, and a host of hop-ups and variations on the five-lift scaffold were all designed and checked in advance to give the project the flexibility it needed to succeed.
An 80% reduction in installation time over traditional scaffolding in this area assisted the overall project in its successful delivery and the additional pre-mobilisation engineering works allowed for the majority of modifications required without the project being halted while assessments were completed.
Span offered CAD and engineering support for the project duration to allow the client to react to unforeseen circumstances and the swift removal of the system allowed normal bridge operations to resume earlier than planned.