###### Abstract  
The planning of production, logistics, and maintenance in mechanized tunneling relies on project-specific conditions and assumptions about numerous production parameters. Analyzing multiple scenarios for TBM production is crucial for ensuring robust project flow. Process simulation models are valuable for this analysis. However, deviations from the plan often occur due to uncertainties in initial assumptions and unforeseen events during construction, especially given the variable ground conditions in TBM tunneling. This paper presents a concept for adapting offline simulation models used in the planning phase for real-time optimization by integrating actual project data. Continuously updating these models with new data from the construction site improves performance predictions. The concept involves integrating current construction progress into the simulation model and updating the originally assumed input data with project-specific actual data. An example study demonstrates the continuous adjustment of a simulation model and its impact on project duration prognosis. The enhancement of the prognosis by integrating real-time data is investigated, and an initial assessment of the earliest possible time for an update is made. The benefits of using real-time data in process simulation during construction are discussed, highlighting the improved accuracy in performance prediction and the potential for more efficient project management.  
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In TBM tunneling, different machine types are used depending on the ground conditions and the groundwater level. Shield machines are used for tunneling in soft ground, in unstable ground conditions, or below groundwater level. These machines are surrounded by a cylindrical steel construction, the shield, which provides support to the excavated cavity until the final tunnel support is installed (Figure 1).  
Shield tunneling consists of two alternating core processes, excavation and ringbuild. During excavation, the soil is excavated by a cutting wheel equipped with excavation tools. Subsequent to this, the process of ring building commences, wherein reinforced concrete segments are assembled to form a ring that secures the excavated cavity and forms the final tunnel lining. The core processes are continuously supported by numerous support processes, including the supply and disposal of material or the backfilling of the annular gap, which is created during excavation between the surrounding soil and the exterior wall of the tunnel. A disturbance in any individual process can lead to a disturbance in the entire tunneling system, thereby inducing further disturbances through propagation effects. The influence of external logistics is used here as an example. The frequency with which trucks remove much from the above-ground site storage affects the utilization of the storage. Since the advance speed has to be reduced or even stopped when the muck storage is full, the frequency of the muck trucks also affects the performance of the TBM. Predicting TBM performance therefore depends on many logistical aspects. It is essential to take into account the interactions among individual processes to ensure the robustness of the planning process. A comprehensive summary and formalization of the different production and support processes was given by [PERSON] [5].  
Process simulation is an appropriate tool for analyzing these complex relationships. To date, the use of process simulation models for mechanized tunneling has been limited to the planning phase. Extending the simulations to include the integration of real-time data during project implementation could support continuous improvement in the models, decision making in the event of unexpected disturbances, and robust incident management. This is of particular interest for mechanized tunneling, as many input variables in planning are based on assumptions and are often subject to uncertainties and inaccuracies and therefore deviate during execution.