Update on Investigation of New Side Impact Test Procedures in Japan

The safety of cars in side impact accidents has been improved since regulations requiring improved performance in a side impact test (for example, ECE/R95 or FMVSS 214) have come into effect in many countries. However, many people continue to be injured in side impact accidents; and, as a consequence, further improvements in a car’s performance in side impact crashes are desired. This paper has been written to provide an update on what future improvements may be required, and presents a study of recent side impact accident data collected in Japan and the effectiveness of the curtain side air bag in side impact crashes. In evaluating the improvements of a car’s safety performance in side impact accidents, the National Transportation Safety and Environment Laboratory (NTSEL) previously has conducted research and published papers about various full car side impact tests, for example, the regulatory ECE/R95 tests, moving deformable barrier (MDB) tests, and car-to-car tests. However, NTSEL considers that it is necessary to gain increased knowledge regarding the injured body regions of occupants involved in a side impact accident in order to evaluate the effectiveness of safety equipment in future side impact accidents. In this study, the authors first investigated the recent side impact accident environment from accident data in Japan. In this review, the authors examined trends regarding collision partners, injured body regions, injury levels, and the curb mass of both the struck and striking vehicles. The results indicate the following two findings: Firstly, the head and chest are the main injured body regions in the fatal and serious injury side impact accidents. Secondly, the percentage of lighter vehicles is relatively large for the struck vehicles, and the percentage of heavier vehicles is relatively large for the striking vehicle in these fatal and serious injury side impact accidents. Secondly, the authors investigated the occupants’ seating postures in cars running on Japan’s roads. The results show that 56% of the drivers’ heads were in line or overlapped with the vehicles’ B-pillars. A more detailed study about the seating postures of the driver also was conducted. Thirdly, the authors conducted MDB-to-car side impact tests according to the Regulation ECE/R95 specification with the exception of the seating positioning of the dummy. The target vehicles were two same model Kcars, which are categorized in Japan as a very small size vehicle, and the seating positions were adjusted so that the dummy’s head overlapped the B-pillar. One K-car had a Curtain Side Air Bag (CSA) and a Side Air Bag (SAB) installed; while, in the other K-car, the CSA and SAB were not installed. The authors compared these test data, previous test data collected for small vehicles, and the Japan New Car Assessment Program test data for the same model K-cars as well as other small cars. The compared data included the injury measures and kinematic behavior of the ES-2 dummies in the front seats of the struck vehicles. It was demonstrated that the CSA and SAB were effective for reducing the number of head and chest injuries in car-to-car crashes; however, it was also demonstrated that the degree of effectiveness was influenced by their design.