This text presents the results of the joint research initiative "Numercial Simulation in Tunneling". In doing so it provides a thorough guide to improving the safety and economy of tunnels by discussing the application of numerical simulation methods to assist tunnel engineers. Numerical simulation tools for the estimation of the required tunnel support and the required construction measures are described in this book. By using them, it is possible to study the impact on the construction and on the environment at the planning stadium and during construction. This will result in an improvement of the safety and economy of tunnels.