In the Lower Inn Valley of the Tyrol, Autria, the existing railway line has been upgraded. In the course of these works a two-track tunnel with an excavated diameter of 13.03 m was built in the track section H3-4 Münster/Wiesing. The tunnel was excavated with a slurry TBM. Demanding geotechnical conditions on this difficult contract necessitated changes to the overall concept. After tendering and the award of contract, the client and the contractor started the construction phase with different expectations. We report on the strongly differing experiences of the parties during the construction of the works. At the end, we draw conclusions for both parties from the experience gained during the successful completion of the project.