Philosophy in the use of models for the elaboration of a transportation plan.

The purpose of this paper is to expound a philosophy of the use of models in the elaboration of a development plan for a transportation system. In the greater Paris area, in the past ten years or so the offer of transport has grown appreciably and a number of decision- making aids have been both designed and used in order the better to exploit the existing system. The experience gained in the course of that work has enabled a use philosophy of such aids to be developed. The outcome of that experience is considered here.