抄録
Decrease in traffic volume M depending on the heavy snow circumstance is an index of snow disaster at Hokuriku, and is discussed analytically as follows : firstly a factor Fw, depending on the day of week and independent of the snow circumstance, is introduced and M is modified into M* without this effect. Secondly three factors depending on snow are intoroduced, that is, Kh in term of daily snow fall, KH of snowcover depth and KD of effect by countermeasure. For example, the empirical expression is given, using a constant Mo, by
M=MoFwKhKHK, Kh=1/(1+(h/Xh)mh)
and so on. The result decreases the relative deviation into 9.5% of Mo from 20.3% for M, and the effects of different factors are found that Kh>KDKH.