Samenvatting
The maker of a traffic model is confronted with questions to which he, by means of the traffic model, should be able to give an answer, at least according to the questioner. It must be said that many of these questions cannot always be answered within the given time. On the other hand the model-builder also will put some questions that cannot be answered with the wanted exactness. In this paper something is said about these problems and some recommendations are made.