There is a relatively sharp rise in the number of accidents on days of renewed precipitation after a period of fine weather or at times of seasonal change to snow and ice conditions. The main reason for this is the relatively long time taken for a driver to adapt himself to 'critical' weather conditions, caused by cyclogenetic influences, with their substantial influence on the state of health of a person. Surveys by the hamburg police in collaboration with the medical and meteorological research centre enabled the accident situation to be related to critical weather conditions and amounts of precipitation in comparison to days with substantial precipitation but no cyclogenetic influences. A percentage comparison between days with and without critical weather showed the accident rates on days with critical weather were higher by: 51.3% for all accidents, 37.5% for accidents involving personal injury, and 49.6% for the number of injured, than on days without critical weather. A correlation study gave the following results: for similar initial factors, the correlation coefficient on days with critical weather was 0.611 and on days of non-critical weather 0.241. There is a clear relation between time of precipitation and accident rate.
Abstract