Abstract
We aimed at clarifying an actual state about an accident that a branch or a trunk of a roadside tree fell and hit a victim directly on the Tokyo prefectural road. We investigated and analyzed the data in connection with a roadside tree in Tokyo Prefecture. As the result, it became clear that the kind of trees with many numbers does not necessarily have many accidents. And it was suggested that there are some types of the accident which is easy to cause according to the kind of trees. Especially about a Zelkova Tree (Zelkova serrata), there were many accidents by branch breakage. And the accidents tended to occur frequently in the same route. It was suggested that there is relationship between that accidents by branch breakage occur and that Zelkova Trees became large through years. On the other hand, about a Japanese Pagoda Tree (Styphonolobium japonicum) etc., there were many accidents by collapsing. And it was suggested that decomposition and a cave have a close relation to this kind of accident.
