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It is generally accepted today that the cervical spine of a car occupant who is involved in a low-speed rear end impact may suffer from soft tissue neck injuries leading to long-term impairment. Therefore, to assess the risk of sustaining such injuries is a major issue in traffic safety, and various neck injury criteria are being discussed for this purpose. In this study a new candidate for such an injury predictor, called Nkm, was developed. Results from a total of 37 sled tests with various car front seat models were evaluated to validate the new criterion. These results indicate that the new criterion offers the possibility to assess the kinematic phase of forward motion of a rear-end collision. In contrast, the NICmax which was also calculated for these tests allows to evaluate the retraction phase only. Furthermore, the influence of the seat design on its protective potential could be related to the Nkm values obtained.

Reducing the weight of vehicles could be a strong means of reducing fuel consumption in urban traffic. Published accident and injury statistics however show an inverse correlation of vehicle mass against injury severity in car to car collisions, above all in head-on collisions. This inverse correlation is in part caused by current crash test standards, where compatibility in collisions between cars of different size and weight is not a requirement. Compatibility in frontal collisions demands for significantly different deceleration-time curves in rigid barrier impacts for cars with different weight. Low mass vehicles (LMV) must meet compatibility criteria to comply with current injury criteria in real car to car collisions. Cars designed according to compatibility criteria can change future accident and injury statistics in a way that injury severity in LMVs can be reduced significantly.

In a collision of a low mass vehicle (600 kg) against a typical compact car (1200 kg), both vehicles cruising at 50 km/h, the LMV will experience a Δv of 20 m/s and a mean deceleration level of 45 - 50 g, approximately. The restraint systems of such vehicles must be adapted to this specific situation in order to guarantee a level of passive safety equal to current standards. The purpose of this study is to show that, in sled tests, FMVSS 208 and European occupant protection criteria can be met under the conditions encountered in a LMV, utilizing restraint system components which are appropriately adapted and optimised with respect to the severity of the crash situation under consideration.