Rapid installation of Forth Road Bridge expansion joints
The overall goal of this project was the successful replacement of the 16nr expansion joints on the Forth Road Bridge. This was one of a number of both critical and technically challenging repair scopes that have been able to progress following the opening of the adjacent Queensferry Crossing and the resulting ability to divert the majority of traffic across the new structure. These scopes had been in the pipeline for many years but delayed in anticipation of the new crossing being available to avoid travel disruption.
The client required access to be provided for the replacement of the expansion joints at the North Side Tower and the S3 pier. Their original plan was to utilise traditional scaffolding however this choice of equipment in other areas resulted in lengthy build durations, ongoing as built design issues and a frequency of contact points that resulted in an impractical working space for the repairs to progress.
Span Access – a HAKI Group company – were contracted to provide a suspended access solution that specifically utilised the existing gantry rails to result in reduced contact points and a more useable working area.
In addition, a solution that could be built at deck level and lifted into location would help mitigate an already compromised project schedule by quickly opening up additional repair areas for the clients’ team to work on.
Span designed a solution based around their proprietary TechniSpan system and opted to use the 750mm aluminium beams to allow them to comfortably span the 13m distance between gantry rails while still permitting a workable live load.
The equipment was constructed at deck level and electric winches installed to the gantry rail using the existing maintenance gantries. The platform was then lifted to height, transferred to beam trolleys, and towed along the gantry rails to its required location. Handrails and access ladders were installed to suit the geometry of the bridge onsite.
- Rapid installation of access with 4nr shifts required per location. This was achieved through building the access at deck level and therefore no requirement to get large volumes of materials to height.
- Reduction in working at height due to construction of access at deck level.
- Modular system easy to modify should unanticipated project requirements demand it. This proved to be of benefit as the repair of the expansion joists in these locations progressed.
- Overall a more cost-effective solution compared to traditional scaffolding primarily due to the minimal labour required but also simpler design with 6nr contact points resulted in a smoother temporary works checking process and a short premobilisation phase.
- Span Access’ experience working on these iconic structures resulted in minimal issues across design and installation.
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