Tunnelling started as an empirical art and is now on the way to become a scientifically founded branch of engineering. "Scientfically founded" means that the methods of tunnelling can not only be annunciated by some few authorities but also rationally explained, checked and - what counts in universities and continuing education institutions - learned. In the Summerschool "Rational Tunnelling," an international group of select specialists addressed an audience from 14 nations with lectures intending to illuminate various aspects of tunnelling. The present volume contains the notes of these lectures. Aspects are: Some principles for the design of lining Constitutive models for numerical simulations Tunnel design in soft-ground-insights from monitoring and numerical modelling Ground reinforcing and steel pipe umbrella system in tunnelling Problems of TBMs in water bearing ground Estimating ground water inflow into hard rock tunnels - the problem of permeability Performance monitoring for tunnel design verification Instrumentation to assist with tunnel construction control Geophysical investigations: Integrated seismic imaging system for geological prediction during tunnel construction What tends to go wrong in tunnelling Application of design-build contracts to tunnel construction Cost and schedule management for major tunnel projects with reference to he Vereina tunnel and the Gotthard base tunnel Technical features for quality procedures in tunnelling Hard rock TBM advance rates Tunnel refurbishment Fire protection in tunnelling