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Lithium-ion cells are being used in an increasing number of electric and hybrid vehicles. Both of these vehicle types contain many cells. Despite various safety measures, however, there are still reports of accidents involving abnormal heat, smoke, and fire caused by thermal runaway in the cells. If thermal runaway in one cell triggers that of another and thus causes thermal runaway propagation, this can lead to rupture of the battery pack, car fire, or other serious accidents. This study is aimed to ensure the safety of vehicles with lithium-ion cells by clarifying such accident risks, and so we investigated the process of thermal runaway propagation. In the experiment, we created a battery module made of seven laminate-type cells tightly stacked one on another. Then, we induced thermal runaway in one of the cells, measured the surface temperatures of the cells, and collected video data as the process developed. As a result, all of the seven cells underwent thermal runaway.

The number of traffic deaths in Japan was 4,612 in 2011. Looking at the road accident fatalities, it revealed that pedestrians accounted for the highest number in 2011 (1,686, 36.6%). To develop safety countermeasures to decrease the severity of injuries and to reduce the number of deaths in traffic accidents, the detailed characteristics of pedestrian injury in vehicle-to-pedestrian crashes are necessary. The purpose of this study is to understand the scenarios of vehicle accidents in which pedestrians suffer fatal injuries. In the present study, we investigated the characteristics of pedestrian injuries in fatal crashes from accident analyses and compared them to head injury severity levels in impact tests against a road pavement and vehicle contact surfaces.

The Japan New Car Assessment Program (JNCAP) was launched in 1995 in order to improve car safety performance. According to this program, installation conditions of safety devices and the results for braking performance and full- frontal crash test are published every year. The side impact test was introduced in 1999. In 2000, the offset frontal crash test was also introduced. From the viewpoint of such a diversification of the crash tests, an overall assessment method for the safety of cars which reflects road accidents has been demanded. In this study, we have examined a new overall assessment method capable of reflecting the traffic accident situation in Japan using methods employed or planned by USA-NCAP, Euro-NCAP, TUB-NCAP and others as references. As the basic concept, JNCAP conducts three types of crash tests including the full-frontal crash test, offset frontal crash test, and side impact test to assess the dummy injury parameters.

The first purpose of this study is to clarify the relation between the car impact velocity and pedestrian injury severity or mortality risk. We investigated the frequency of serious injuries and fatalities of pedestrians using vehicle-pedestrian accident data from the database of the Institute for Traffic Accident Research and Data Analysis (ITARDA) in Japan. The vehicle types considered are sedans, minivans, and box vans (ordinary automobiles) and light passenger cars and light cargo vans (light automobiles). The results revealed that a 10-km/h reduction in impact velocity could mitigate severe pedestrian injuries in cases involving impact velocities of 40 km/h or more for the five vehicle types analyzed. Specifically, if the impact velocity was 30 km/h or less, the frequency of serious injuries was less than 27% and the frequency of fatalities was less than 5% for the five vehicle types.