Roadways have a lower capacity and a longer travel time under snowfall condition. As for planning of transportation in snowy area, introduction of traffic management is important for securing road traffic. The purpose of this study is to survey the effect of snowfall condition on traffic characteristics. The main results of this study are as follows:
1)Average speed showed a decrease of approximately 18km/h (30%) in snowfall condition. And there is more little difference in speed distribution than normal condition.
2)The boundary between free-flow and congested-flow by the time headway is 5.5 seconds in normal condition and 7.0 seconds in snowfall condition.
3)A difference of speed between free-flow and congested-flow in snowfall condition is larger than in normal condition.
4)Traffic volume of following in snowfall condition decreases by 34%. compared with that in normal condition.