Graham West studies the technical innovation in the historical development of the tunnelling industry, covering a period of more than 150 years. Beginning in 1825, when Marc Isambard Brunel invented the tunnelling shield for driving the Thames Tunnel, West brings us up to the present with the current renewed attempts to bring about the construction of a tunnel under the English Channel. The main section of the book comprises a detailed examination of the major technical advances in both hard rock and soft ground tunnelling, discussing such topics as pressurized face shields, extruded linings, hydraulic rock drills, and small-diameter tunnelling systems. In addition, the development of a highly innovative tunnelling industry in Japan is discussed, a parallel is drawn between this development and that in nineteenth-century Britain. From these discussions, and the identification of the conditions that have allowed technical innovation to flourish in the tunnelling industry, a classification for technical innovation is proposed, which could be applied to technology in general.