California Partners for Advanced Transportation Technology

SIRIUS (Systeme d'Information Routiere Intelligible aux Usagers) is the largest urban field operational test of the advanced traveler information and automated traffic management system in Europe. With variable message signs, SIRIUS has been in operation in the Paris region since December 1992. This study is a preliminary investigation of the effectiveness of the SIRIUS system in traffic management.The concern of the paper is the extent to which drivers respond to real-time traffic information and the consequential changes in link flow under SIRIUS. Time-series traffic data were analyzed to measure changes in mean flow rates at a selected link. The study indicates that variable message signs do influence drivers to choose lesser congested routes when provided with real-time information. Graphical analysis using cumulative arrival curves suggests that diversion behavior is closely associated with information pertaining to the level of congestion. The results of the study indicate that as congestion becomes heavier, drivers are more likely to respond to variable message signs.