The term “temporary works” is not well understood outside the construction industry. We talk to Neil Robinson, FCBC Temporary Works Co-ordinator for Foundations & Towers, to find out why the work of his team is so important to the success of the Forth Replacement Crossing project.
Temporary, but vital for success
Q: What are temporary works?
A: Temporary works cover a wide range of infrastructure equipment which makes the construction of the permanent works (ie. the new bridge itself and the connecting roads) possible. Every construction project – from the Pyramids to the new Queensferry Crossing – requires temporary works. Scaffolding is a good example. It enables the people and materials required to construct, say, a house to get to where they are needed. Without temporary works, nothing would ever get built!
Q: What are the main temporary works on this project?
A: In my area of responsibility (the towers and foundations), the main temporary works are called climbing formwork. Made from steel and timber, these are essentially moulds used to form the four-metre-high concrete sections which will make up the bridge’s three towers. The formwork on this project has been specially designed to be adaptable in size. As the tapering towers rise section by section, the formwork will rise alongside ready to mould each successive section, ultimately forming the tallest bridge towers in the UK at up to 210 metres. As far as the bridge foundations are concerned, the enormous steel caissons and cofferdams are essentially temporary works which were vital to allow construction of the reinforced concrete tower bases. Elements such as scaffolding, ladders, gangways, hoists, lifts, crane foundations and safety rails all made access to the site possible. Indeed, the giant shearleg crane used to place the caissons on the seabed was technically part of the temporary works equipment.
Q: What are the biggest challenges facing the team?
A: With a project of this type, we continue to face big challenges as construction work progresses. The caisson and cofferdam installations were major challenges, but we now progress onto the tower and pier construction using a total of five sets of climbing formwork systems. At the same time, the deck is being prepared for installation as soon as the towers and piers reach sufficient height. The challenge facing the temporary works design team is to ensure that all of the temporary works are complete and in position on time to allow the construction team to progress uninterrupted.
Q: What gives you the most satisfaction?
A: They say a temporary works engineer like me doesn’t just see what has been built but always asks how it was built. At the end of this project, like any other, we know that our work will either be invisible or will have been removed altogether. But we will also have the satisfaction of knowing that nothing could have been built in the first place if it had not been for our input. So, now that the caissons have been successfully sunk into the seabed and the tower foundations are under way, we can be proud of the role the temporary works team is playing in this massive project.