News / 30.11.21
Forth Rail Bridge, Northern Approach Viaducts
Spotlight on Denholm Industrial Services Ltd, winner of the 2021 NASC Awards Project of the Year (Turnover £5m+) category, sponsored by TRAD Hire & Sales Ltd.
Project name: Forth Rail Bridge, Northern Approach Viaducts
Why did you select the above project for consideration in the Scaffolding Project of the Year (Turnover £5m+) category?
Denholm Industrial Services Ltd: The enquiry for this project came in the spring of 2019 from Balfour Beatty to provide the access, containment, blasting and repainting of the five spans of the Northern approach viaducts of the Forth Rail Bridge. Denholm industrial Services was selected to provide a tender proposal for this project because we have a long track record of multi-skilled services across many industrial and marine sectors.
We selected this project for consideration because of its technical complexity and because of the close interfaces and consideration that have been given to the residents and environment of the world heritage site of North Queensferry. The project exemplifies the dedication to safety, quality, production, and sustainability that Denholm industrial Services strives for on each project.
Please provide an overview of the scaffolding works undertaken:
Denholm: The scaffolding is a suspended access slung from the bridge steelwork with access via scaffold staircases and goods and personnel hoists. The system chosen for the design was Plettac Metrix and the reason for this was to reduce the amount of loose materials needed to be used at height above the village, the productivity benefits over tube and fittings, plus the greater control over design features using systemised components.
The design was created using a combination of historic drawings from the 1800’s and site surveys to determine the geometry of the structure. The system scaffold components lend themselves to greater control over the finished scaffolding, but also required very careful planning to ensure that any clashes with the permanent structure could be mitigated and allowed for in the design.
Each scaffold span was a 50m long x 10m wide x 10m high suspended birdcage with shrink-wrap encapsulation to the outer faces. The scaffolding was required to allow the Denholm industrial Services painting team access to all the steelwork sections on the bridge spans and to collect and contain all arisings from these re-preservation works.
How does this project best highlight your skills and expertise?
Denholm: The experience and knowledge of the estimating team to be able to ascertain the scope and nature of the works and to encapsulate this in a competitive package that would deliver value to our clients and a return for the Denholm industrial Services business was key to this project being a success.
The scaffolding design was an iterative process between the Denholm industrial Services design team, operations team, Balfour Beatty, Arup, and Network Rail. The bridge structure has finite limits to its structural capabilities and careful consideration of how much scaffold could be erected concurrently required accurate data to be provide and assessed by the temporary works and permanent works teams.
The environmental effects on the sheeted scaffold structure were also critical to the structural integrity of the bridge. A management plan was developed between all stakeholders to keep within the limits of the bridge to remove the cladding in certain severe weather conditions.
This process would require monitoring and quick planning and reaction to clean the scaffold and prepare for this evolution.
Did the project present any challenges? If so, how did you overcome these challenges?
Denholm: The system scaffold and bridge interface was a challenge, as some of the historic structural data was a little less accurate than expected. The initial construction phases meant close contact between the scaffold team, project manager and technical manager. Once the pattern for construction became familiar the scaffold team quickly became very efficient at creating this structure.
The logistics of keeping the areas below the works safe meant adopting safe methods of work to tether tools and scaffold equipment and erecting safety netting in critical areas. The development of the safety netting system to protect the village from the works developed during trials to allow for a localised protection system to be drawn out and withdrawn at each shift.
This meant that protection was provided when works were being carried out but the netting system was not exposed to environmental conditions that would be detrimental to it and the bridge structure.
NASC Awards Judges comments:
“Denholm Industrial Services demonstrated their competence in delivering a technically complex scaffolding solution, overcoming site specific challenges through bespoke design, pioneering techniques and stakeholder teamwork. The judges saw a commitment to providing safe methods of working, access and protection to the workforce and public which they felt were truly commendable and only possible through utilising the highest levels of expertise in the industry. This is why Denholm Industrial Services are the winners of the 2021 NASC Project of the Year.”
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