Route choice models play an important role in many aspects of transportation analysis, when the usual shortest path paradigm is too unrealistic (real-time information systems, traffic simulation, etc.). Developing operationnal route choice models involves various challenges. In this talk, we will consider 3 of them: - data collection, - the large size of the choice set, - the high correlation among the alternatives. For each of them, we will identify the difficulties, and present recent research results developed at EPFL.