The Forth Rail Bridge is an iconic cantilever bridge constructed in the 1880’s and spanning the Firth of Forth just North of Edinburgh. It continues to remain a significant and admirable engineering structure of the Victorian era.
A rope access inspection of the South Span had highlighted a number of fractures in the steelwork that required to be repaired. Suitable access was required to allow repairs to the steelwork and coating works.
The bridge has existing out-of-service mobile gantries which, had they been operational, would have been the ideal platform to carry out the repairs.
Span designed and engineered a bespoke temporary version of the permanent gantries using our in-house capabilities. The working platform comprised of our in-house TechniSpan x750 system. This was integrated into two fabricated steel suspension frames that ran along the existing gantry rails.
Folding guardrails allowed the platform to pass the structural transverse beams and the platform was able to be relocated by the onsite contractor following a handover and training from Span.
The installation was constructed offsite at our premises and transported using specialist haulage to a local marine contractor for onward shipping to the underside of the first repair location. Our operations team went out ahead of time to install winches and the platform was lifted from the vessel and commissioned for use in a shift.
We revisited site to offer ongoing support for the first few relocations until the clients’ team were comfortable with all aspects of its operation, and they assumed full responsibility for its maintenance in accordance with our supplied O&M manual.
Addressing the access requirements using this system gave the client multiple benefits.
The hire costs for access provision were significantly reduced, with the client gaining full access to the structure while hiring a small square meterage.
All repair works were undertaken from a secure, handrailed environment, thus driving a better quality of structural repair and coating application. Further defects were also highlighted and addressed upon installation of the platform, as the team were able to conduct a more accurate ongoing survey of the structure, with the ability to get closer to the structure compared to rope access methods.
Future economies of scale were also available as the system was equally compatible with the identical North Span which was yet to be surveyed and any remedial works addressed.
Additionally, from a visual perspective, the platform had a minimal aesthetic impact on the bridge compared to a full underdeck scaffold installation or a suspended access platform.