Abstract
As dynamic road traffic information systems and services are largely developed, it appears useful to harmonise and to fix the basis and the structures of the language used, at least inside the same country. Through surveys and monitoring of users reactions and opinions, a first set of rules can be obtained with which to build efficient VMS (Variable Message Sign) messages, and to improve the general impact on traffic management. A French working group, with administration and motorways companies, set up such guidelines for the most current messages provided on interurban motorways. (A)