Abstract
28％ of traffic accidents in Japan are rear-end collision. Multiple collision is 13％ in rear-end collision. Post crash brake system is one of post crash safety technology. Post crash brake system supports driver to stop vehicle in short distance after rear-end collision, to prevent secondary collision. In this study, effectiveness of post crash brake system was examined using driver recorder database. In 64％ of rear-end collision, driver interrupted the brake after the collision. Stopping distance was estimated with time data recorded in drive recorder. The brake assist by post crash system would be effective in 21％ cases to prevent secondary collision. However it is not possible to avoid the secondary collision at a high speed accident. Considering the velocity distribution of striking vehicle in rear-end collision in Japan, the brake assist by post crash system would be effective in 668 cases per year for normal passenger car.
