This thesis addresses two modeling problems related to pedestrian flows in train stations, namely that of estimating pedestrian origin-destination demand in rail access facilities, and that of describing the propagation of pedestrians in walking facilities. For both problems, a mathematical framework is developed at the aggregate level, describing pedestrians in terms of groups with the same departure time, origin and destination. The proposed demand estimator is probabilistic and accounts for within-day dynamics as well as for natural fluctuations across days. It is inspired by estimation methodologies that are used in the context of vehicular traffic. Critically, the proposed methodology takes the train timetable and ridership data into account, significantly improving the accuracy of the estimates. Other information sources, such as link flows or sales data, can also be incorporated. To describe the propagation of pedestrians, walkable space is considered as a network of pedestrian streams that interact locally. Based on the continuum theory for pedestrian flow and the cell transmission model, a computationally efficient model is obtained that can be used under a wide range of traffic conditions. An optional extension allows considering anisotropic flow, where the walking speed depends on the walking direction. Such a formulation is advantageous in particular at high densities. Throughout the thesis, a case study of Lausanne railway station is considered. A detailed discussion of the usage and level-of-service of its rail access facilities is provided, underlining the performance and practical applicability of the proposed modeling framework. The contribution of the thesis is fourfold. First, it provides a dedicated estimation methodology for pedestrian OD demand in train stations. Second, it proposes a novel macroscopic network loading model for congested and multi-directional pedestrian flows. Third, it presents a detailed case study of a Swiss train station, for which a rich data set is collected. Finally, it applies the aforementioned modeling framework to that case study, and provides practical guidance for its use in the planning and dimensioning of rail access facilities. Beyond train stations, the developed modeling framework can be readily applied to various other pedestrian facilities, such as airports, shopping malls, stadiums or urban walking areas. For instance, it may be used to support the organization, planning and design of such facilities, to safely and efficiently manage pedestrian flows using real-time monitoring and control, or to assess and optimize the safety both during normal use and in case of emergency.