An important problem in improving mobility services consists in analyzing the transportation offer with respect to the demand of mobility. The purpose is always the assessment of the service for its improvements. This activity can be approached having all the historical data, while in most cases is not realistic due to the expensive process of data collection and lack of details about the movements of travelers at the bus stops in terms of pick-up and drop-off for each bus line. To deal with these issues, in this paper, a model is provided to support mobility analysis in public transport networks. Our model operates first by analyzing the service offer, provided by mobility operators, and the service demands. Then, the model allows to evaluate the number of people who are picked-up and dropped-off at a stop. The performance of the model has been validated by comparing the observed values obtained from a field observation. The research and tool have been developed in the context of MOSAiC research project partially funded by Tuscany Region, with DISIT lab, ALSTOM, Municipia/Engineering, TAGES and CNIT research centers.