Proton Beam Therapy Unit


The world’s first proton beam cancer therapy unit to be built entirely below ground. One of London’s most ambitious excavation projects in years.


Proton beam therapy is used to treat cancer with minimal damage to surrounding tissue. This 34,500 m² building consists of five above-ground storeys of clinical space with approximately the same depth below ground to house four floors of proton gantries. The excavation is large enough to contain the Royal Albert Hall. As well as the gantries, specialist accommodation includes a dedicated critical care facility, full diagnostic imaging department and theatres.


The 28.5-metre basement presents many challenges. Including highly-specialised medical facilities and working at vast scale in central London. This is an extremely constrained urban site. Not only is it bordered by existing UCLH live buildings within Bloomsbury Conservation Area, it’s also very close to the London Underground infrastructure. Limited plant space in the second-floor basement sits above the 4m-thick concrete PBT gantry bunkers housing the proton beam treatment rooms. Preventing leakage is paramount. Servicing such an environment was highly complex. especially for incoming utilities and air supply. Indeed, the biggest challenge of the project is providing routes for delivery and replacement of the gantries and cyclotron.


Careful coordination is everything. As well as close collaboration with up to 20 different clinical departments. The scheme holds a BREEAM pre-assessment of Excellent and is a Government Exemplar project in using BIM Level 2. This was used to develop the model of the phased construction and has been key to success. The project also meets the latest Part L energy targets, with high efficiency and low-energy servicing strategies to control costs once in operation.

Key Facts

Bloomsbury, London
Client: UCLH
Photographer: Scott Tallon Walker



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