Project: New Tower Hamlets Town Hall
Client: London Borough of Tower Hamlets
Main contractor: Bouygues
Contract value: £109.5m
Contract type: JCT design and build
Concrete frame: Bouygues
Structural engineer: Elliott Wood
M&E: Designer Group
Architect: Allford Hall Monaghan Morris
Project start: August 2018
Completion date: Q1 2022
The Royal London Hospital in London’s eastern district of Whitechapel has stories to tell, as might be expected, having been at its present address since 1757.
Upwards of 250 years has accumulated quite an historical collection, such as the mounted skeleton of ‘Elephant Man’ John Merrick, as well as a forensic medicine section that includes original material on Jack the Ripper, Dr Crippen and the Christie murders.
What time also tends to confer is listed status, and The Royal London is no exception.
This means that the project to transform the building into a town hall to house the consolidated functions of Tower Hamlets Council – with ground floor public-facing facilities including a library, with offices on upper floors – must step carefully around the structure’s Grade II level.
In this case, that translates to retaining a significant proportion of the structure, including the centre-front element with its portico that faces the A11 Whitechapel Road.
Immediately behind the site is the Skanska-built new Royal London Hospital – meaning the venerable old hospital building, unused since 2012, was ripe for redevelopment. And new life it will certainly receive, as part of a £1bn masterplan to regenerate the area.
Following on from a pre-construction service agreement, which saw the French-owned contractor get onto site last August, it won the work last December to redevelop and expand on the remaining elements of the four-storey structure.
When Construction News visits the site in September, Bouygues has moved on and is overseeing subcontractor Keltbray, which is tackling the partial demolition that is mainly taking place at the rear of the old hospital.
This includes the Grocer’s Wing on the east side, though Bouygues must retain the facade, as well as taking down the west wing – which was connected to an adjacent dental hospital – and the rear portico.
Once the main build begins, Bouygues will construct two distinct frames with two different materials behind the Grocer’s Wing facade.
“We have a constraint in this area with the presence of an LUL [London Underground] tunnel,” says Bouygues project director Jerome Magnier.
Last September, Tower Hamlets Council awarded an £8m contract to Bouygues to carry out preparatory work on its new town hall ahead of the main construction taking place.
Opening in 2022, the new town hall will be part of the ‘Whitechapel Vision’ – one of London’s largest regeneration projects, which includes the opening of Crossrail at Whitechapel Station in 2019, a new £300m life-sciences campus and seven new public spaces.
The ground floor of the new town hall will be open for the public to use for meetings, to access council services and to visit the library.
A French expat, he explains in Parisian-accented English that while not trafficked by trains, it is still in use as a service tunnel and every care must be taken to ensure works don’t adversely affect it.
“We are not allowed to pile at all and there is a 3 m line of influence we must not enter,” he says.
“All our piles are set away from this line. Within that [part] of the new build, we won’t be able to install a concrete frame or load the tunnel.”
This led to the contractor opting for steel in the area immediately behind the facade that sits over the tunnel.
Mr Magnier explains that the design requires the reuse of the foundations from the former Grocer’s Wing spine wall to support the columns.
“The problem was the lack of recorded information to define the structure”
Jerome Magnier, Bouygues
The steel frame in the space vacated by the Grocer’s Wing will attach to the heavier concrete frame that will form the new-build element of the town hall further to the rear, and hence well away from the LUL service tunnel.
Bouygues will self-deliver the concrete frame for the up-to-six-floors-in-places new build once operatives have installed CFA piles of 450 to 600 mm diameter that will go down 18 m to 28 m.
The original building stood at two storeys, with two added later and elements of this will be remodelled with structural changes that will include new risers and door positions.
“The fact that we have to do these structural alterations inside to adjust its design for its new requirements has been a challenge,” he says, alluding to the soft strip revealing a frame that wasn’t always as anticipated.
“The problem was the lack of recorded information to define the structure.”
The Grade II-listed building has seen substantial additions over the centuries. Contrasting construction techniques and materials, situated cheek by jowl in the space of a single corridor or room, portray how methods to achieve the same objective have evolved over time.
“In this building, we have every possible type of flooring structure since the 1800s,” says Mr Magnier.
“In the basement, which was the first part of the construction, we have timber floors. In other ages, steel beams were added to support the loads of the equipment the hospital needed, and we also have concrete and steel floors – every possible kind of structure.
“The only thing that is consistent is the brick walls,” he adds, noting it as a UK peculiarity. “[And] strangely, where our structural engineers were expecting steel beams and columns after the soft strip on the fourth floor, [bearing in mind] the time of construction, it’s all solid brickwork.”
The design has had to be adjusted to match what was found during works.
“Once the soft strip completed, we did a point cloud survey to get a 3D [representation] that we could use in our BIM model,” adds Mr Magnier.
This allowed the team to superimpose the architectural and structural models so engineer Elliott Wood could define the alterations required for the now-revealed original frame to conform to requirements of the building’s new use.
Other elements have made the job less than straightforward. “We had to deal with a lot of pre-enabling works with the soft stripping, asbestos removal and demolition,” says Mr Magnier. “It’s not something we always have to do in London.”
“It’s really two projects in one, but not two individual projects – they are combined”
Jerome Magnier, Bouygues
Alongside the new-build work is a restoration programme. This includes the meticulous logging of anything uncovered during soft strip work, such as plaques, as well as the reinstatement of the retained facade to return it to its listed-status glory.
“It’s really two projects in one,” says Mr Magnier, “but not two individual projects – they are combined.”
He adds that the site’s location has made logistics something of a challenge (see box, below).
“It’s really going to be an issue,” he says. “We are not only going to deliver a curtain wall for the rear facades, but there will be restoration of the front facade at the same time.
“The storing of goods onsite [and] manoeuvring of all the scaffolding around the existing building – all that is going to be having a major impact.”
The biggest challenge
Most inner-city sites face logistical challenges, and this one is no exception. With the project wedged between the arterial A11 Whitechapel Road to the front – a red route at that – and the new replacement Royal London Hospital immediately to the rear, careful logistics planning has been paramount.
“Logistics was definitely a challenge,” says Mr Magnier, “because we [only really] have access from the [Whitechapel Road].”
Bouygues needed another option and has been liaising with the new Royal London hospital to get one or two morning deliveries. But this is hardly a game-changer and can’t be used for the delivery of concrete, for example.
“We are currently planning to pump all the concrete from the front [of the site] to the rear during the construction of the frame,” he says, explaining that self-delivery of the frame will be a challenge in a constrained environment.
“We are still studying the logistic arrangements – it’s a just-in-time delivery project,” he adds.
Meanwhile, the roof will have to be replaced. “We will have to completely re-waterproof the main building,” Mr Magnier adds.
CN’s site tour arrives at the ‘clock room’ in the attic above the front portico. It’s a space with a sad and macabre history, and was home to John Merrick after he was admitted to the hospital in 1886. A wall-mounted placard records this with text and photos.
“When we soft-stripped, we discovered that the partitions were not only timber framed, but also supported the roof,” he says (see picture).
“So we will have to [make adjustments] by splicing the A-frames of the roof structure to transfer the loads onto the facades, in order to get rid of the intermediary supports.
“It’s quite strange on a roof like this – I would not have expected to have intermediary supports because [the space] is not that wide, they’re just supporting the side pitched roof cheeks, not the main front one.”
Mr Magnier points to another feature he says is a first for him and which must have been difficult to build: “This is the first time I’ve ever seen concrete that has been poured in such a thin layer on an inclined mansard roof like this.”
But given all of this, he makes it clear that finding – and overcoming – these issues are part of the appeal.
Mr Magnier says: “This is what I like. If you just do typical construction and can just repeat what you’ve done from the previous project, that is quite boring. I like challenges and discoveries.”
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