Evaluation of Restraint Type and Performance Tested with 3- and 6-Year-Old Hybrid III Dummies at a Range of Speeds

Children under six years of age who are prematurely restrained in adult seat belts are at more than 3 times increased risk of injury as compared with children in child restraint systems (CRS). As a result, CRS (child safety seats and booster seats) are recommended as appropriate restraints for young children and use of different types of child restraints is increasing rapidly. The objective of this study was to begin to evaluate the performance of multiple restraints at a range of speeds, utilizing the Hybrid III 3- and 6-year-old child dummies. Injury measurements were compared for a 3-year old restrained in a forward facing convertible child restraint, a backless belt-positioning booster seat and in a lap shoulder seat belt; and, for a 6-year old restrained in a backless belt-positioning booster seat, a high back belt-positioning booster seat, and a lap shoulder seat belt. A matrix of tests (total of 18) at speeds of 24, 40, and 56 kph were used in the evaluation.

Lowest injury measurements were obtained for the 3-year old in a forward-facing convertible child restraint and for the 6-year old in belt-positioning booster seats demonstrated maximal differential performance in the 56 kph test. In particular, the 6-year-old Hybrid III dummy in the high back booster seat showed extreme cervical flexion and chin-face contact with the chest with measures predictive of severe injuries that are not observed in field data. Additional tests are required to understand the interaction of the dummy with the high back belt-positioning booster seats to provide valuable information for future improvements in dummy biofidelity and restraint performance. In addition, further research is also needed to understand the contribution of booster seat design to the differential performance of the high back and backless boosters.