Tunnellingisanexcitingandrapidlyevolvingtechnology.Pioneeringprocesses are commonplace and innovative thinking continues to rewrite the rules. In civil engineering, tunnelling is one of the few areas where new horizons are constantly being discovered. But for the profession to reach its full potential, tunnelling needs to be more accessible to those talented engineers in search of new challenges and keen to make lasting contributions to society. In the eyes of too many, tunnelling is still seen as the exclusive domain of too few: a mysterious art form, accessible only to those who have already spent countless years perfecting their approach, a skill whose secrets remain suppressed. Over the following pages I hope to show that tunnelling need not be a closed book. I have omitted methods and de?nitions that depended more on h- torical precedent than modern scienti?c evaluation. Instead of confusing the reader with countless details and de?nitions that are in any case open to change, I have focused on the underlying concepts that make tunnelling e- ier to grasp. Sowhilethisbookisdesignedtoprovideaconcise,up-to-dateandusefulframe of reference to all those newly quali?ed and engaged in the ?eld, I hope that it will also serve to reveal to those talented engineers who thought they had found their niche above ground the very real opportunities and unanswered questions that await them underground.