The thesis is divided into two sections. The first part presents the fundamentals of a tender in Austria and abroad. The different competitive tendering procedure and construction contracts will be discussed. Furthermore, the methods for ground characterization are explained in accordance with the "Guideline for the Geotechnical Design of Underground Structures with Conventional Excavation" by the Austrian Society for Geomechanics and as well as especially the classification of tunnelling classes according to the Austrian standard ÖNORM B 2203-1. Subsequently, the construction contracts abroad will be discussed. In particular, the VOB part C for Germany, the SIA 118/198 for Switzerland and for the international field FIDIC and NEC contracts are presented. In the second part of the thesis the tender is examined by means of a concrete power plant project. The advantages and disadvantages of the classification of tunnelling classes are derived by means of practical experience. Finally, the opportunities and problems are interpreted and solutions are proposed.