The VIPAFLEET project aims at developing a framework to manage a fleet of Individual Public Autonomous Vehicles (VIPA). We consider a fleet of cars distributed at specified stations in an industrial area to supply internal transportation, where the cars can be used in different modes of circulation (tram mode, elevator mode, taxi mode). We treat in this paper the pickup and delivery problem related to the taxi mode by means of flows in time-expanded networks. This enables us to compute optimal offline solutions, to propose strategies for the online situation, and to evaluate their performance in comparison with the optimal offline solution.