In transportation applications such as real-time route guidance, ramp metering, congestion pricing and special events traffic management, accurate short-term flow prediction is needed. For this purpose, paper proposes several novel online Grey system models (GM): GM(1,1|cos(?t)), GM(1,1|sin(?t),cos(?t)), GM(1,1|e-at,sin(?t),cos(?t)). To evaluate the performance of proposed models, they are comp...