FATALITIES CAUSED BY SNOW IN HOKKAIDO AND ATTEMPTED COUNTERMEASURES: Judgment criterion of snow removal on roofs based on risk analysis for fatalities and structural damage

In Hokkaido, accidents involving people due to snow have been occurring in every winter. The fatalities caused by snow in Hokkaido on 2006 heavy snowfall or after is largest number in Japan. 60 to 70% of all accidents were caused by snow removal of roofs such as falling from roof and falling from ladder in contents of the damage factors. According to Building Standard Act of Japan, it is possible to reduce snow load on roofs conducted by snow removal only in the regions that to rise on roofs is traditional. However, the reduction of snow load isn’t recognized by prefectural ordinance. Nevertheless, those accidents caused by the snow removal have been occurring frequently. To reduce the accidents caused by the snow removal, the authors analyzed damage risk using statistics data of 2006 or after, and then analyzed performance against snow load subjected the wood-frame houses build in Hokkaido. The authors proposed also methods of the snow removal based on those results obtained in the risk analyses.