Recent increase in the use of child restraints, particularly belt-positioning booster seats, requires closer evaluation of their performance. Previous studies by Menon, et al. and Sherwood, et. al. have shown that the Hybrid III 6-year-old dummy produced unusual head-neck kinematics and neck injury measures that exceeded critical values while restrained in a high back booster seat. Both studies used similar high back booster seats for the tests but were done at different speeds and conditions. This study was undertaken to initiate a process to evaluate the performance of multiple high back booster seats by conducting a series of sled tests. These 56 kph sled tests were done using the Hybrid III 6-year-old child dummy in 4 different high back booster seats and their injury measures were compared.

Results of these tests have been summarized in this paper and provide an evidenence for a differential performance among the various designs of high back booster seats compounded with the established lack of biofidelity of the Hybrid III 6-year-old dummy. Injury tolerances exceeded for the 6 year-old dummy in two of the high back booster seats for the Head Injury Criteria, in three of the seats for chest G’s and in all the four seats for the Neck Injury Criteria. In two of the seats with similar design, the kinematics of the head was unusual, mainly due to the extreme hyper-flexing of the neck. This high neck injury measures obtained from the sled tests are in contrary to the field data, which show that children in beltpositioning booster seats suffered virtually no injuries to the abdomen, neck/spine/back. These test results and field data highlights the need for further research to be conducted to improve the biofidelity of the Hybrid III 6-year-old dummy neck and to understand the variation in the high back booster seat designs at higher speeds.