This report discusses the following main characteristics of Hard Soils – Weak Rocks (HSWR) influencing tunnel design and construction: (1) The presence of systematic structural features which prevent representative sampling, thus making classical Soil and Rock Mechanics testing methods inapplicable in measuring mechanical properties and necessitate the use of empirical classification methods. (2) Stiffness and strength of HSWR are usually too low compared to the geostatic stresses at the depths where these materials are encountered, resulting in face instability and time dependent behaviour (squeezing conditions).