The BTS Specification for Tunnelling has become the standard industry document for tunnelling contracts, and forms the basis of tunnelling specifications for projects throughout the world. The specification has been revised in this third edition to reflect current industry best practice and to take account of the many advances in the field of tunnelling which have occurred over the last decade. Coverage of sprayed concrete has been expanded in recognition of its increased usage around the world and there are new sections on sprayed applied waterproof membranes and jacked box tunnelling. All references to codes, standards and other design documents have been comprehensively updated.