This Specification for Tunnelling has been completely updated to refelct the many significant changes in tunnelling techniques. It is written to be used as a contract specification on its own, or in conjunction with other standard specifications on multi-disciplinary projects. The original Model Specification for Tunnelling was the first document produced for the industry with the specific aim of establishing a common standard for the design and construction of tunnelling in the UK. This new edition continues to draw heavily on the practical experience of both corporate and individual members of the British Tunnelling Society, and provides a sound basis for specifying tunnelling design and construction. This updated specification is a considerable advance on the original, and should continue to be the de facto standard for tunnelling in the UK.