Abstract
An investigation has been made of how the accident rate - based on road accidents reported by the police - varies with the amount of rain in a day (24 hours). Data for all paved government roads in Sweden during the period 1977-1980 have been analysed. The data, which were originally compiled for other purposes, were used because they are very extensive and remain unique for Sweden. The results show that the accident rate can be 50-100% higher during days with heavy rain compared to days without rain. The results also indicate that the accidents rate during days completely without rain is slightly higher than during days with small amounts of rain. (A)