Building information modelling has played a major role in keeping a heavily serviced hospital building project on schedule after a huge delay early in the programme.
Project: Royal United Hospital pathology and mortuary building
Client: Royal United Hospitals NHS Trust
Main contractor: Kier
Architect: Nightingale Associates
Structural engineer: Capita Symonds
M&E subcontractor: Lorne Stewart
Start date: October 2012
Completion date: September 2013
Kier is building a new pathology and mortuary building for Royal United Hospital in Bath, having won the scheme through the ProCure21+ framework.
The first job the main contractor and its framework partner Capita Symonds faced was choosing between three options for the facilities.
A refurbishment and extension of an existing building on the hospital site was ruled out because the structure did not have the space for the level of services required. This left two new-build options, with the smaller footprint selected to minimise the loss of space on the hospital grounds.
The three-storey building will have mortuary facilities, along with welfare and office space on the ground floor; an automated lab for blood sample testing on the first floor; and a populated lab for histology and cytology on the second floor.
The project team helped decant IT staff from an existing single-storey structure on the chosen site, which was then cleared of asbestos and prepared for demolition. At this point in early 2012, however, the project was dealt a major blow when hydrocarbons were found in the ground.
“This delayed the project by about six months,” says Capita Symonds structures lead Shaun Fraser. “We had to run site investigations to establish what kind of hydrocarbons there were, how old they were and where they were on the site.”
The team discovered the material was too deep in the rock strata to excavate. So it had to run a further series of tests to prove to the Environment Agency that it would not escape from the hospital grounds until it was broken down sufficiently.
“To an extent, we were at a standstill for six months,” says Capita Symonds M&E project lead Gary Sian. “The design was complete but we could not start on site.”
Groundworks finally began in October 2012, but with a fixed completion date in September 2013, the complex project had to be condensed into less than a year.
And the problems were far from over. Piled foundations were no longer possible after the hydrocarbon discovery. “We did not want to penetrate through the rock strata and give hydrocarbons a path to enter into a watercourse or anything else,” Mr Fraser explains. “So we used concrete pads.”
Once the ground was prepared, the concrete frame went up quickly and the roof was being worked on by Christmas.
“We did not want to penetrate through the rock strata and give hydrocarbons a path to enter into a watercourse or anything else”
Shaun Fraser, Capita Symonds
“The frame was purposefully kept simple because we wanted it up as quickly as possible,” Mr Fraser says. “The stairs were all precast, for example.”
A steel roof minimised the weight on the foundations and a composite deck fitted to house the extract fan compound. Once the building was watertight, the external envelope and services work began.
BIM to the rescue
This is when the BIM model came into its own. CAD drawings from architect Nightingale Associates were converted into an initial BIM model by the structures team at Capita Symonds before the project began.
This was passed on to the services team, which started to involve subcontractors and work out the fine details of how elements of the services would fit together in the finished building.
“As the subcontractors procure materials, they input those elements into the model,” Mr Sian says. “Traditionally we would have produced a design and the contractor would have had to input all the information about equipment purchased; Kier has not had to do that on this project.”
Capita Symonds did have to physically build some components for the project ahead of time purely to input them into the BIM model.
“We had to make a socket, for example, so the model knew what it was,” Mr Sian explains. “If we were drawing in 2D we would just have used a symbol.”
The picture was built up to allow the team to see exactly how clashes would be avoided – which pieces of ductwork would go below or above others, for example.
“We have completely avoided days when someone comes in and can’t do their job because of a clash with another trade”
Gary Sian, Capita Symonds
This precise model removed the need for fiddly and time-consuming revisions on site when the services were installed under time pressure.
“We have completely avoided days when someone comes in and can’t do their job because of a clash with another trade,” Mr Sian says. “There is no ‘we haven’t got the pieces, where’s the nearest wholesaler?’”
This certainty of routing, along with offsite pre-fabrication of kit, meant M&E subcontractor Lorne Stewart used just two workers to install all the ductwork in the building. “Traditionally there would have been a gang of up to 15,” Mr Sian points out.
Fast service installation
The project relied on quick and efficient installation of services to meet rigorous healthcare building standards.
The mortuary has strict temperature guidelines and also requires a high level of air change, as well as negative pressure, to ensure air does not leave the space even if doors are opened.
Dedicated low-level extract is being installed from downdraught benches with perforated plates in the postmortem suite.
The automated labs have high levels of heat gain due to the equipment in them and rely on mechanical ventilation via active chilled beams.
“We have a dedicated air system for each department,” Mr Sian says. “Effectively this is five or six buildings rolled into one.”
Further downdraught benches and extraction systems are needed in the second-floor staffed labs. The chimney stack then has to rise high above the roof and send extracted air at high speed into the atmosphere to avoid contamination risk.
Heat for the new building is being supplied from the hospital’s existing boiler house – requiring 200 m of 150 mm-diameter piping.
“We had early meetings with Lorne Stewart and the trust,” says Capita Symonds mechanical lead Gary Hughes. “We originally had it running underground, but on closer inspection this became too narrow and congested, so it was ruled out.”
Space was eventually found in the ceiling voids of the main hospital corridors, but this required a painstaking physical inspection.
“We would have faced a lot more challenges if we had not used the BIM model”
Gary Sian, Capita Symonds
“Everyone on the project has an idea for this kind of job,” Mr Sian says. “You go through them all and eventually you find a solution.”
M&E installation work was taking place on site when Construction News visited earlier this month, and the project remained on course to be completed by September in time for the hospital’s switchover. Much of this is credited to the use of BIM.
“We would have faced a lot more challenges if we had not used the BIM model,” Mr Sian says. “Without it you can’t visualise the services going in and you always end up with clashes. This way the contractor can just follow the model – gaps are already there for ductwork to go through.”
The reduction in onsite modification also minimises the risk of dips in quality, which is as equally important as speed when the services will be performing such closely measured functions.
Tests on the services are being run by the M&E contractor as it works, with approved sections then handed over to be fitted with ceilings, walls and doors.
After the second fix of M&E and internal finishing work, a final period of commissioning will take place before completion in September.
The scheme has been used as a BIM training tool for one engineer, who is now “flying” on the technology, according to Mr Fraser. It seems he could not have had a better project to learn on.
The site chosen for the pathology and mortuary building is tightly hemmed in on all four sides by other facilities on the Royal United Hospital campus.
This is important to allow access from the main hospital street for both people and services.
However, the site presented several challenges to the project team. The client’s office overlooks the building site, as does a geriatric ward.
“The mortuary was placed on the opposite site to the geriatric ward so that it faces away from it,” Mr Fraser explains. “That is the kind of detail that went into the original design process.”
The mortuary will be next to a car park, with a discreet entrance slightly back from the edge of the building.
“From the outside you can’t really tell that it’s a mortuary,” Mr Sian says.
The case for redevelopment
Royal United Hospital opened on its current site in Bath in December 1932 to meet growing demand in the region.
The hospital is currently undertaking a £40m programme over five years to clear away old buildings, bring cancer care under one roof and improve facilities and parking.
The current pathology, histology and haematology department is a mix of buildings from the 1930s, 70s and 80s. Neither these nor the mortuary are ideally located within the hospital campus.
“The existing buildings are coming to the end of their lives, and science has moved on,” Mr Sian says. “The business case identified the need for new facilities.”
Royal United Hospital Bath NHS Trust provides acute treatment and care for 500,000 people in Bath and the surrounding towns and villages.