Skanska has had to navigate a number of tricky conditions, not least working on a live hospital site, in order to build a new surgery centre and family accommodation at Great Ormond Street Hospital.
Project: The Premier Inn Clinical Building
Client: Great Ormond Street Hospital
Contract value: £50m
Contract type: Design and build
Main contractor: Skanska
Start date: June 2014
Completion date: August 2017
There was one question Skanska had to answer before it started work on Great Ormond Street Hospital’s Premier Inn Clinical Building.
“Are you going to be able to build this in a way that is sympathetic to the children?” Skanska project director Burgess Pocock explains after showing Construction News around the site.
“GOSH’s top value is ‘child first and always’,” he continues. “That was given to us in spades and got us thinking about the logistics, sequence and methods we were going to employ to deconstruct the [existing] building.”
The Premier Inn Clinical Building is the second of two new buildings that make up the Mittal Children’s Medical Centre at GOSH.
The first – The Morgan Stanley Clinical Building – was built by Bam and opened in 2012.
Skanska’s second phase of works include a surgery centre, which will provide inpatient treatment for babies, children and young people for a variety of issues, including general surgery and urology treatment. It will also contain 48 inpatient beds, two theatres, bed bays and anaesthetic care units.
Elsewhere in the Premier Inn Clinical Building there will be large bedrooms to allow parents and carers to stay with their children and a 16-bed isolation facility for children with poor immune systems or infectious diseases.
The site is surrounded by a live hospital, which has patients flowing through its doors day and night – something that was at the forefront of Mr Pocock’s mind when starting the scheme.
Design and demolition
“The first challenge was how you are actually going to knock the building down,” Mr Pocock says. “There were risks associated with that because if you’re going to knock something down you need to think about how it will affect the stability of the [existing] building.”
A design team, including architects Llewellyn Davis and Structural & Services Engineer WSP PB, was already involved in the project before Skanska won the design and build work as main contractor, although a large part of the design work had been completed before it started on site.
Mr Pocock says this meant the contractor had to understand the constraints of the design during the tender process.
“If you’re going to knock something down you need to think about how it will affect the stability of the [existing] building”
Burgess Pocock, Skanska
Keltbray, which was also directly engaged with the client before Skanska began, was appointed to carry out dismantling works. Mr Pocock says his team worked with Keltbray to decide how best to take the building down, which resulted in “largely slicing [the building] into pieces and lifting it out with tower cranes”, he adds.
The team used two tower cranes through the demolition process, the largest of which was able to lift 6.5 tonnes at 60 m. This helped to minimise the level of disruption on the live hospital.
Another area where the construction and design team had to work together was around the delivery of the concrete frame, the result of which delivered future benefits for the client (see box).
Noise, dust and vibration
Other causes for concern in relation to working on a live site were around noise, dust and vibration.
While these problems are common to many schemes, they were particularly relevant to Mr Pocock and his team due to the work taking place on top of a live theatre.
“This has been a huge thing for the job,” he says. “We have sensors all around the site for all three of those issues [noise, dust and vibration] – which come through on my phone if there’s been an alarm.
“Thresholds were agreed at contracting stage, so the minute that we go over, it raises an alarm. Then we investigate and we stop the operation or speak to the department.”
“We have sensors all around the site for [noise, dust and vibration] – which come through on my phone if there’s been an alarm”
Burgess Pocock, Skanska
The theatre below is where the hospital conducts MRI scans. These machines are hyper-sensitive to vibration, so Skanska had to consult with equipment supplier Siemens to agree what they could do and when.
The scanning department agreed to work between 1pm and 10pm so the construction team could exceed its threshold limits before 1pm. Mr Pocock says this agreement worked so well that the image department kept to the agreed routine beyond the required period.
But the machines added another layer of complication to the mix.
Skanska Great Ormond Street Hospital 13
Mr Pocock explains that some of the equipment used by the hospital has “nuclear properties”. This meant Skanska had to fit pipes in certain rooms to provide a safe route to take the blast into the atmosphere if the machine “decided to blow up”.
Tight working environment
Another challenge for the team was the site’s tight working environment. With only one main access in and out, Skanska had to be rigidly organised to minimise disruption.
The team has a “very strict” online delivery system, where it can book slots for each day. Mr Pocock is quick to point out that this is far from a new invention, but he says it is something that Skanska’s entire workforce had to take seriously.
“We’ve got a supply chain that very much embraces Skanska’s values – and if they don’t we don’t work with them”
Burgess Pocock, Skanska
“There is one other [entrance] around the back, but it’s effectively a shared access with the mortuary, so you can imagine we don’t want to particularly use that unless we have to,” he adds.
Elsewhere in the building, Construction News is shown where the new bedrooms and bed bays will be situated. With little space to manoeuvre, it is clear that the need for a tidy working environment is crucial.
“When you walk around the site does it feel cluttered?” Mr Pocock asks, the answer to which is no – this is an immaculate site even at peak construction, with 250 workers, compared with between 70 and 80 during the demolition phase.
Care and concern onsite
Talking about Skanska’s workers provokes a very sincere reaction from Mr Pocock, who begins to explain the importance of “care and concern”. He says it’s about “the actual guy on site”, which allows Skanska to get the job done so efficiently.
Skanska has an Injury-Free Environment programme, which demands that each worker takes responsibility for their own and others wellbeing.
Skanska Great Ormond Street Hospital 11
“We’ve found that has been really well received with the guys – and you will get more out of them because you are treating them like adults. You get the odd one who won’t play ball but they are not welcome on site.
“We’ve also got a supply chain that very much embraces Skanska’s values – and if they don’t, we don’t work with them.”
This care and concern is something that shines through the Skanska team and mirrors the values held by Great Ormond Street Hospital.
A fitting approach to a project that will help medical staff care for children for years to come.
WSP PB designed the job using traditional trough slab construction – a very old and complex technique, which effectively copied the method that was already in place on the lower floors of the building.
Skanska looked at using ‘Cobiax void formers’, which are lightweight concrete slabs within which sit bubbles filled with reinforced steel and recycled plastic. Skanska project director Burgess Pocock says this provided a number of benefits, including using 31 per cent less concrete.
By using the Cobiax void formers, Skanska estimates it has saved around 20 per cent of the CO2 emissions when compared with using solid concrete slabs. These slabs are also narrower, which increased the floor-to-ceiling heights.
“The main benefit for GOSH here was that if they want to rip out those services in 10 years’ time to do something else, it’s so much easier to fix in flat slab,” Mr Pocock says. “In trough slab construction it’s really difficult to do all the fixings, or if you want to change the wall position.”
Mr Pocock says the change in method was cost-neutral but GOSH opted for the Cobiax system because it offers future flexibility.