Аннотация:To explore tunnel effects on ring road traffic flow, a macroscopic urgent-gentle class traffic model is putforward. The model identifies vehicles with urgent and gentle classes, chooses the tunnel speed limit asfree flow speed to express the fundamental diagram in the tunnel, and adopts algebraic expressions todescribe traffic pressure and sound speed. With two speed trajectories at the Kobotoke tunnel in Japan,the model is validated, with good agreement with observed data. Numerical results indicate that in thecase of having no ramp effects, tunnel mean travel time is almost constant dependent on tunnel length.When initial density normalized by jam density is above a threshold of about 0.21, a traffic shock waveoriginates at the tunnel entrance and propagates backward. Such a threshold drops slightly as a resultof on-ramp merging effect, the mean travel time drops as off-ramp diversion effect intensifies gradually.These findings deepen the understanding of tunnel effects on traffic flow in reality.