In Europe it is largely admitted that a better coordination between urban planning and transport is a necessary condition for setting sustainable urban development into motion. This idea is largely supported by the observation that the only metropolitan areas which have succeeded in containing automobile use (Bale, Berne, Zurich, Karlsruhe...) are those which combine public transport development with various kinds of automobile use restrictions as well as urban planning and development measures. Despite the consensus, debate over the objectives and means behind this coordination remains relatively limited. In a research project carried out in collaboration with the EPFL's Laboratory of Urban Sociology, we developed a critical approach of this technical and political recommendation, focusing both on local representations and practices and the way they change over time. This communication presents the arguments which guided us in defining our main questions, our approach to analyze the urban trajectories of transport and urban planning and several of our main results.