The London Clinic New Cancer Centre provides state of the art cancer treatment facilities in a new-build hospital wing in Paddington. The building features a 16m deep basement, painstakingly inserted amongst an array of movement-sensitive existing structures, including a Grade II listed Georgian terraced house and the shallow brick-built Metropolitan / Circle Line underground running tunnel.
The site area measures just 1200m², making space critically important and providing the design team with a serious challenge to fit essential treatment equipment into the confined volume available.
Key amongst the installations were two 100 tonne ‘LINAC’ linear accelerator units, which use intense localised radiation to eradicate cancerous cells. The processes involved in using LINACs are highly sensitive to movement, while the equipment itself requires significant shielding to prevent the unintentional leakage of radiation. The usual method of achieving this is by using either lead sheathing or massive, heavily-reinforced concrete.
The structural engineer proposed the positioning of the LINAC units at the lowest basement level, coupled with the use of ‘Ledite’ block wall screens, thereby saving the cost of a cumbersome supporting structure and yielding significant spatial benefits The 1.5m thick basement floor was designed as a piled slab, in order to reduce the possibility of ground-related movements to an absolute minimum.
The floor layout also features a three storey deep lightwell, allowing natural daylight to penetrate down to the oncology waiting area, while doubling up as the principal access route for the future removal and replacement of the LINAC units if necessary.
"The London Clinic’s New Cancer Centre site bristled with every complexity a structural engineer could wish for - all of them over-come in efficient, technically satisfying ways. Here is an example of an appropriate solution, driven by a series of structurally logical choices, starting with the fundamental decision to position the greatest loads at the lowest level."