In collaboration with the Swiss Federal Railways (SBB-CFF-FFS), various challenges associated with pedestrian flows in train stations are discussed at the example of Lausanne railway station. For this site, a rich set of data sources including travel surveys, pedestrian counts and trajectories has been collected. The report is organized in three parts. First, an empirical analysis of the aforementioned data sources is provided. The main focus thereby lies on the identification of periodical movement patterns both in time and in space. Second, a methodology for estimating pedestrian origin- destination (OD) demand using various information sources including the train timetable is discussed. This methodology is applied to the case of Lausanne railway station, and results are provided for the morning peak period. Third, a pedestrian flow model is presented which, for a given OD demand, allows to estimate pedestrian travel times and density levels based on an empirical pedestrian fundamental diagram. This model is applied to study pedestrian movements in an underpass of Lausanne railway station, including an assessment of pedestrian level of service. Instead of focusing on mathematical details, the present document provides a general overview of the problem of modeling pedestrian flows in railway stations that is accessible to practitioners. Suggestions for further literature are provided throughout the document.