We were at the heart of a digital collaboration that pushed the possibilities of 3D design and off-site construction to deliver the largest capital project in Wales ahead of schedule.
The Grange University Hospital is Aneurin Bevan University Health Board’s new £350 million, 450-bed, specialist critical care facility in Cwmbran, Wales. The hospital opened four months ahead of schedule in November 2020. This achievement – a first for a hospital of this size – was the result of the project team committing to a BIM Level 2 digital approach from the outset and maximising off-site construction.
Working alongside contractor Laing O’Rourke, architects BDP and mechanical and electrical consultant AECOM; WSP provided structural, civil, drainage and other engineering services to the project through our local office in Cardiff. The whole project team committed to a digital approach using BIM to design for manufacture and assembly.
“We’ve delivered the largest project in Wales ahead of programme, under budget and to a high standard. We couldn’t have achieved this without the dedication shown by the WSP teams.”David Leverton, Technical Leader, Laing O'Rourke
Overall, the project achieved 50-55% off-site construction. Compared to a traditional approach, this saved 42 weeks of the programme – reducing it by 23% – and increased productivity by 45%. It also saved 237,099 hours of on-site labour, reducing the health and safety risks associated with working on site. Bringing complete manufactured elements such as bathroom pods to site instead of individual materials reduced vehicle movements by 30%, reducing disruption and emissions.
To achieve this remarkable result, the whole design team worked entirely in 3D – beginning earlier than usual to thoroughly test the process. Our designers modelled the structural elements of the building in a protocol that could be transferred seamlessly to the factory. In a standard approach, they would then have received them back in 2D for checking. But this project took things further, with the reviewing and checking done in 3D. This made communication easier and reduced the risk of mistakes. For example, simple colour coding made it easier to check that the right rebar was in the right place.
“The process for checking the design in 3D hadn’t been done before so we put together a best-practice way of working that everyone could follow. The approach saved us time, it saved the factory time, the elements got to site quicker and ultimately the hospital was built quicker.”Matt Lewis, BIM and Digital Lead, WSP
The thousands of elements constructed off-site included 243 bathroom pods, 1,200 precast shear walls, 661 corridor service modules and 774 precast panels that form the envelope of more than half the hospital. Manufacturing these panels, which combine façade elements with structural backing, off site and fitting windows at the same time meant there was no need for scaffolding on the site.
Slabs were designed with a 75mm rebar biscuit on the bottom so they could be dropped by crane straight onto trestles, and workers could then walk on them safely to install rebar. The precast biscuit also came with edge trims and handrail sockets so these could be installed easily to keep people safe.
“With every detail crucial to realising the potential benefits of the design for manufacture and assembly approach, managing the flow of information was crucial. We developed trackers to ensure everything stayed on schedule and we could get critical elements through the factory on time.”Stuart Renshaw, Project Lead, WSP
The team were also thinking about the future too, with the design capable of accommodating changes to the hospital’s layout. Each column position includes a spare hole – so, for example, if departments were to swap round, new drainage could be added. The hospital’s entrance area can have more storeys added on top, and future extensions to the catering and office block can use the existing foundations. The 3D model would give a future design team all the information they needed.
The 3D model had other benefits too. With all the design data available to them through the model, the Health Board can see everything it needs to know to plan future maintenance effectively. The model also enabled virtual reality to be used for design reviews and to give staff a virtual tour of the building.
Benefits of off-site construction
Manufacturing building elements in a controlled factory environment, instead of constructing them on a site at the mercy of the elements, has a number of advantages:
- Improved quality
- Increased speed
- Reduced waste
- Reduced health and safety risk
With design and fabrication teams all working efficiently in intelligent 3D formats, the ward area was handed over to the client in April 2020 in time to provide extra capacity during the Covid-19 pandemic. The whole hospital was officially handed over, with zero defects, and opened to patients in November 2020.
The project won the Digital Construction Award at the Constructing Excellence in Wales Awards 2020. But our team aren’t resting on their laurels; they will now apply their experience from The Grange University Hospital to other projects. They have already completed a feasibility study with architect BDP for a new emergency department at Bristol Royal Infirmary. Using modern methods of construction, including off-site manufacturing, would enable the project to be built efficiently on a constrained site.
The success of The Grange University Hospital has proven the worth of collaborating in 3D to design, model, coordinate, manufacture off site, and install building elements. It sets the bar high for the future.