In this diploma thesis, the impact of the construction of the building BOKU Türkenwirt on the tunnel “Großer Türkenschanztunnel” is investigated, based on numerical simulations. The tunnel is located below the construction site and it is a part of the track of railway-line S45 of the Vienna local train service. Because of the tight train schedule, the sustainment of the structural integrity and serviceability are of major interest for the public transport system of the City of Vienna. Previously to this work, simplified finite element Plaxis 2D calculations evaluated at certain cross-sections were undertaken. In contrast to that, the numerical analysis in this work is conducted with the finite element program Plaxis 3D, which allows the determination of spatial deformations on the whole building site. Furthermore, the results of the 3D calculations will be compared with real-time measured data, measured by a monitoring system installed inside the tunnel. This thesis is split into three major parts, “Introduction of the Project”, “Modeling” and “Evaluation of the FE Results”, which allows a detailed presentation of the numerical investigations and results. The first chapter includes a description of the building project and the tunnel, as well as a detailed demonstration of the underground situation. Additionally to that, an insight into the geotechnical report is provided and descriptions of the 2D model and the monitoring system are given. The second chapter deals with material models, which were used during the numerical analysis (Mohr-Coulomb Model and Hardening Soil Model with small strain stiffness) and the associated material parameters. Furthermore, a description of the basics of the 3D modelling as geometry, soil layers, structural elements, modelling phases, loading and finite element mesh is included. Finally, the third chapter forms the core of the thesis and is comprised of a detailed presentation of the numerical calculation results. First of all, the presentation includes an overview of general results from several modelling phases. Moreover, comparisons with the numerical results from the simplified 2D model and the monitoring system are discussed. The latter of these two comparisons is divided into a discussion of the quantities and directions of the deformations.