The objective of the study presented by this paper was to determine whether belt-positioing-booster seats incorporate seat bottom design features, identified by previous research, to minimize the risk of submarining. The booster seats were evaluated through inspection and testing. The geometry of the BPB’s seat bottom was measured and recorded. The comparative restraining ability of the BPB’s seat bottom ramp was tested. The compressibility of the BPB while seated on a vehicle seat was tested. The compressibility of the BPB alone was also tested using the test specified in the Canadian and Australian/New Zealand standards.

The inspection and load testing of various BPBs, as reported in this paper, reveals that BPB seat bottom designs vary significantly. Some BPBs incorporate significant seat ramp geometry and have very little compressibility. Others have no seat ramp at all and have very high compressibility. It is critical that BPB manufacturers understand the importance of antisubmarining seat bottom ramps and low compressibility of the seating surface, and incorporate these features into all BPBs. To ensure this and do so in a manner that is consistently compatible with vehicle seats and seat belts, the authors recommend that NHTSA develop and incorporate requirements into FMVSS 213 specifying the BPB’s seating surface geometry and compressibility characteristics, including the seating surface compressibility requirement specified in the Canadian and Australian/New Zealand standards. In lieu of such requirements, the manufacturers of BPBs and automobiles must work together to ensure that the BPB component integrates properly with the seats and seat belt systems at all automobile occupant positions that can be used by a child to ensure that submarining is prevented.