Considering all expected and unexpected conditions in the a-priori design is acceptable only in special cases. For safe and economical tunnel construction the residual risk needs to be managed by appropriate monitoring and a safety management system. The paper addresses requirements for the geotechnical safety management, as well as state-of the-art monitoring and data evaluation techniques in the context of the observational approach. Experience with safety management systems over the last two decades shows that the risk can be significantly reduced. Case histories are used to demonstrate the potential of proper monitoring and safety management. Keywords: Residual Risk, Tunneling, Monitoring, Safety Management 1. Introduction Uncertainty is unavoidable in underground projects. It originates from the impossibility to completely investigate the geological and geotechnical conditions, even if considerable effort has been made during the preparation phase.