Various research studies performed at different Institutes (Geigl et al, 1994;​ Deutscher, 1994) have shown that current car seats are by no means optimised with respect to the protection of occupants during rear end impacts. Sled tests performed with volunteers and PMTO's (Geigl et al, 1994) have shown some weak points of selected car seats. In order to obtain more objective criteria for the safety of current and newly developed car seats (Muser et al,1994), it seems to be important to improve the quality of the measurement tools (Scott et al, 1993;​ Muser et al, 1994) for the assessment of the kinematics of head and cervical spine during simulated rear end impacts.

In a collaboration between Swiss, Swedish and Austrian Universities, sled tests allowing a comparison of head-neck kinematics between volunteers, PMTO's, a Hybrid III dummy equipped with a standard neck, and a Hybrid III dummy equipped with a RID-Neck (Svensson et al, 1992) have been performed. Identical test conditions have been chosen as far as possible in repeated tests to ensure a good comparability of the different tests. Two types of car seats were used at impact velocities ranging from 6 to 15 km/h. The mean sled deceleration’s were varied between 3 g and 6 g.