The first combined permanent and secondary sprayed concrete lining.

The CombiShell™ tunnelling method was used to form complex underground structures required to accommodate the baggage handling equipment under the operational airport at Heathrow, resulting in a 25 per cent cost and programme saving. It uses a high quality permanent sprayed concrete lining in conjunction with the secondary lining to form the permanent structure.

The system was developed in partnership with Bemo Tunnelling.