This second report by the ITA Working Group on General Approaches to the Design of Tunnels presents international design procedures for tunnels. In most tunnelling projects, the ground actively participates in providing stability to the opening. Therefore, the general approach to the design o[ tunnels includes site investigations, ground probings and in-situ monitoring, as well as the analysis of stresses and deformations. For the latter, the different structural design models applied at present--including the observational method -are presented. Guidelines [or the structural detailing of the tunnel lining and national recommendations on tunnel design are also given. It is hoped that the information herein, based on experiences from a wide range of tunnelling projects, will be disseminated to tunnel designers throughout the world.