The City’s new 37-storey tower may just be the tidiest site you’ve ever seen – but a meticulous approach is crucial if cantilevering scaffolds over public streets is to be done safely. CN pays the project a visit.
Project: 100 Bishopsgate
Client: Brookfield Properties
Main contractor: Multiplex
Scaffolding subcontractor: GKR Scaffolding
Architects: Arney Fender Katsalidis and Allies and Morrison
Value: £400m approx.
Start date: 2015
Completion date: 2018
London is undergoing a boom in high-rise construction.
All across the capital, from the City to development hotspots such as Nine Elms and Canary Wharf, tower cranes dot the skyline as concrete cores and steel frames rise from the ground below them.
New London Architecture and GL Hearn’s London Tall Buildings Survey showed that in 2016 almost one tower came out of the ground every week, and that there were 455 tall buildings in the pipeline, up from 436 in 2015 (tall buildings being defined as those reaching over 20 storeys in height).
The appetite for designing high in London then shows no sign of abating, even with the looming spectre of Brexit. All of this is going to keep contractors in London busy for some time to come – which in turn means that a great deal of working at height is going to be required.
One of these new towers, located in the City cluster that’s also home to the Gherkin, the Cheesegrater and the under-construction 22 Bishopsgate and Scalpel, is 100 Bishopsgate.
Brookfield Properties is the client behind the project, with the developer having bought out joint venture partner Great Portland Estate’s last remaining share of the scheme in 2014.
The main tower will be a commercial office building set to reach 181 m in height over 37 floors. A smaller seven-storey building, 15 St Helen’s Place, is also being developed with a retained façade next door.
Multiplex is acting as main contractor for the near-£400m project, which began construction in 2015 and is set for completion in 2018, despite receiving planning permission as long ago as 2007.
More on Working at Height
Everything in its right place
Specialist contractor GKR Scaffolding won its place on the project having forged a reputation for high-rise jobs after work for Mace on the Shard.
“It’s pretty unusual to have a Layher staircase like that installed for welfare purposes – it shows the commitment Multiplex have made to this site”
Lee Rowswell, GKR Scaffolding
GKR took Construction News on an exclusive tour of the project, and the first thing that strikes you about the 100 Bishopsgate site is how tidy it is. Everything is in its right place, and despite different kinds of work taking place on different floors, they all look uniform in appearance.
We climb a Layher staircase installed by GKR purely to provide access to the welfare facilities, reaching 22 m into the air in its own right.
GKR Scaffolding director Lee Rowswell says: “It’s pretty unusual to have a Layher staircase like that installed for welfare purposes – it shows the commitment Multiplex have made to this site.”
The staircase provides access to the main core where a state-of-the-art hoist system installed by Multiplex’s in-house plant team takes us up to the fifth floor. This hoist is automated, with the operator pressing a button to use it in the same way that you would use a lift inside a building – a factor that has helped GKR and the other trade subcontractors no end in moving materials quickly and efficiently from the ground floor.
GKR’s scope of works sees it providing a gantry around the full perimeter of the building as well as another Layher staircase in one of the lift cores that extends for the full height of the structure, and will continue to rise with the core as it grows taller.
Tethering for success
Upon reaching the fifth floor, we are able to see up close some of GKR’s most significant work at height on the scheme so far – a cantilevered scaffold that hangs over the pavement of Bishopsgate below, an extremely busy pedestrian and vehicle thoroughfare. The firm will be building scaffolds like this “as and when needed” to help support the installation of the steelwork, as is the case with the installation on show.
With a lot of experience in high-rise scaffolding, GKR operates a 100 per cent tethered tools and fittings policy, with all scaffold boards tethered as well – eliminating the risk of anything falling from height and endangering the public below.
“I always think that our guys are like brain surgeons – they’re calling out to each other as they go, ‘tether, detach’, so they all know what they’re doing”
Peter Cullen, GKR Scaffolding
The firm developed its own Elimin-8 fitting [pictured], a completely fixed tethered scaffold component that GKR claims was the first of its kind to be introduced to the UK market.
The components are carried up in a safety bag which is then tethered to the operative, who is in turn tethered to the scaffold, before the Elimin-8 fitting is securely fixed to the standard. Once secure, the operative unclips from the fitting to leave it in place.
In addition, GKR is providing scaffolding for the retained façade on St Helen’s Place, which, although lower than the high-rise tower, still required some careful planning. “The top two lifts of that scaffold are hanging from steel beams – another cantilever,” Mr Rowswell explains.
GKR’s head of health and safety Peter Cullen emphasises that this meticulous planning of work at height is vital to ensure that everything goes smoothly.
“It’s so well-planned and methodical,” he says. “I always think that our guys are like brain surgeons; they’re calling out to each other as they go – ‘tether, detach’ – so they all know what they’re doing.
“You almost have to fight against complacency setting in when putting up scaffolding on the ground now – I don’t worry about the stuff at height any more as it’s so ingrained, you just have to make sure people have the same attitude to all of the work.”
The cantilever is still under construction when CN visits the site, with the finishing touches to be added within days. Further work in this vein will continue for GKR throughout project, when required, until completion in 2018.
On the topic of safe working at height more generally, Mr Cullen says that huge advances in safety have been made in recent years, with an all-tethered approach now common.
“I’d say that using tethered tools and fittings is now usual practice, almost everyone does it,” he says. “I think we’re heading towards a place where more and more of the scaffolds are built off site, in the yard, and then lifted into place on site. That way you reduce the number of workers and time spent working at height.”
100 Bishopsgate is a project that inherently involves a great deal of working at height – but through detailed planning, GKR has shown that scaffolding specialists can play a vital role in making sure they proceed smoothly and safely.