Sprayed concrete lined (SCL) tunnels are growing rapidly in popularity due to their versatility. The design and construction of both hard rock and soft ground tunnels has been revolutionised by the advent of the SCL method and now the use of permanent sprayed concrete linings has unlocked the true potential of the method to minimise construction costs and times. Yet the complex early age behaviour of the sprayed concrete makes the design difficult and requires a robust management system during construction. Consequently the great advantages of the method must be balanced against the risks, as a few high-profile tunnel collapses have illustrated. Practising engineers on site, in the design office or in client organizations will find this book an excellent introduction. It covers all aspects of SCL tunnelling – from the constituents of sprayed concrete to detailed design and management during construction. Although there is a close interdependence between all the facets of sprayed concrete, few engineers have the right breadth of experience and expertise to cover all of them. This urgently needs to be transferred to the wider engineering community as SCL tunnels play an increasingly important role in the delivery of the underground infrastructure which modern urban life demands. In this second edition, beyond a general updating to reflect new developments, the sections on permanent sprayed concrete, the innovative technology of spray applied waterproofing membranes, fibre reinforcement (both steel and macrosynthetic) and composite lining design have been expanded. Sustainability and environmental impact are addressed in a new section.