The French-German research project Bahn. Ville, dealing with Rail oriented development and intermodality in German and French urban regions, has consisted in identifying the principles and factors of success of an urban development oriented towards rail, and in testing them in the agglomeration of Saint-Étienne. One of the research-actions focussed on identifying and anticipating the potential impacts in terms of urban development of a new transport system, of the tram-train type, on an existing railway line. The effect of the insertion of new stops on the global journey time is one of the criterion of the evaluation of new stops. A simulation method of the journey times is presented in this paper. The interest and the limits of this approach, regarding the rolling stock choice and the insertion of new stops, are emphasized. © 2011 INRETS et Springer-Verlag France.