Snowy cold regions account for 60% of Japan's land area. These regions see many traffic accidents that stem from weather conditions peculiar to winter (hereinafter: "wintry accidents"). Typical examples include skidding accidents on snow-covered or icy roads and run-off-road accidents involving snowstorm-induced poor visibility. As the majority of those wintry accidents are skidding accidents, elucidating the impact of winter weather and winter road surface conditions on traffic accident occurrence may be useful in selecting priority sections for measures against wintry accidents and in appropriately identifying the sections and the times of day that necessitate road management, including snow removal and anti-icing-agent application.