PHD Rises to the top on Big Ben project

It is without doubt the UK’s most visible scaffolding project – encasing one of the world’s famous iconic landmarks that is the Queen Elizabeth Tower at the Palace of Westminster. ScaffMag’s Editor Daniel Norton visited the prestigious PHD Modular Access and Layher project to find out more.

A magnificent international symbol of democracy standing at 96 metres tall, the Elizabeth Tower or better known as Big Ben is the focal point of the Palace of Westminster, which forms part of a UNESCO World Heritage site. The world-famous landmark has chimed through the reigns of six monarchs, and is said to be the most photographed building in the UK. However, years of decay have taken their toll on this world-famous clock tower, with £61m worth of renovation works now underway. The work will involve urgent repairs to cracked and crumbling masonry, restoration and repairs to its leaking roof and a major overhaul of the 159-year old clock itself. The last time Big Ben had a major overhaul to this magnitude was over 30 years ago, in the early 1980s – although scaffolding was last seen creeping up the tower in 1996, for work to stabilise the structure after it was found to be leaning, thanks to the construction of the underground Jubilee Line extension.

In November 2016, main contractor Sir Robert McAlpine Ltd, was awarded the renovations contract who swiftly employed Uxbridge-based PHD Modular Access Services Ltd (Heritage Division), to supply and erect the bespoke 98-metre high, free standing, fully encapsulating scaffold with a temporary roof. PHD are no strangers to working on challenging high-profile projects, as they were recently awarded the ‘Access & Scaffolding Specialists of the Year’ title by Construction News.

Life On Site

Scaffolders got underway on site in April 2017. The highly experienced PHD team opted for the exclusive use of the Layher Allround System Scaffold to provide unobstructed walkways at every level to access the tower. Additionally Layher’s HD Aluminium beams, Public stair access and Protect panel design, were all key elements PHD utilised on the project. Layher’s modular system was chosen over a traditional tube and fitting scaffold for a number of reasons. PHD Heritage Divisional Manager & Design Engineer Chris Berry told me that the Layher System was chosen primarily for its capacity: “The loading capacity of Layher far exceeds any other modular system or tube and fitting scaffold,” he said. Other notable reasons why PHD chose the German system was the speed of the erection and dismantling processes, fewer components required (“so safer by design”) and the steel decks used with the Layher system meeting the fire regulations. During the build, the high profile project has had clear objectives and challenges as Danny Dwyer, Managing Director of PHD, explains:

“All four faces of the Queen Elizabeth Tower have been scaffolded to provide access to the stonework for specialist repairs, importantly, without tying to the fabric of the building itself,” he says. “Because the layout of the adjacent structures meant only one face could be scaffolded fully to ground level, structural steel sections designed and supplied by Sir Robert McAlpine were built up from the ground by PHD to span the adjacent building and roof areas.” He adds: “From this solid base, further scaffold was punched upwards to the full 98-metre height of the tower and ultimately to provide support for the temporary roof at the top.” The lightweight structure has enabled PHD to effectively ‘embrace’ the tower with the scaffold to ensure its stability – each façade consists of a series of compression ties against the stonework to eliminate the need for physically tying into and damaging the building. Particular challenges for the scaffold was to provide gap free access, allow decorative elements of the clock tower to pass through the platforms, yet be protected from damage, and be as close to the working face of the building as possible for the various trades that will now work off the structure. The scaffold also accommodates a bespoke passenger and goods lift to move both men and equipment to the full height of the tower structure. Stonework and cast iron roof conservation, together with improvements to make the structure more environmentally friendly, alongside interior repairs and re-decoration, with a focus on fire protection and safety, are all key elements of the project. The recent ‘topping out’ ceremony has marked the completion of the scaffold access installation – finished on time in just over one year – and has now cleared the way for the specialist stonemasons and refurbishment experts to begin their work.

Team work makes the dream work

To erect such a substantial, complex scaffold consisting of nearly 24,000 individual components a specialist collaborative design team was required to work on what is said to be the tallest freestanding scaffold anywhere in the United Kingdom, if not the world. Both PHD’s in-house design team and the Layher UK team worked tirelessly from concept to reality. Chris Berry explained: “Although I designed the scaffold there was a massive team involved in the design. I drew the scaffold from several detailed concept schemes produced by Nick Geddes team at Layher UK then upon Parliamentary approval we produced the calculations. The team at Layher UK that included Nick Geddes, Anita Singh and Dave Rogerson then created a 3D model in Graitec and analysed the structure with PHD’s in house design team headed up by Raul Bandera with Kalil & Fernando, like I said a massive team.”

Interesting facts

PHD have produced some interesting facts about this 800 tonne beast of a scaffold – they discovered that if all the standards were laid end-to-end, they would reach 9.5 miles! Additionally if all the ledgers, transoms and bracing were added the whole lot would reach 20 miles! Also, if all the decking on the scaffold was added up this would cover almost three average-sized football pitches. Massive eh?

PHD’s impressive scaffold will continue to be seen by the millions of visitors to the capital.The complex renovation works to this iconic landmark are set to continue until 2021. SM