Literature Review and Framework for Identifying Seat Belt Misuse and Misrouting in Frontal Collisions

The effect of seat belt misuse and/or misrouting is important to consider because it can influence occupant kinematics, reduce restraint effectiveness, and increase injury risk. One of the objectives of this study was to identify types of lap-shoulder belt misuse/misrouting and associated injury patterns from a literature review. Belt misuse included shoulder belt only, lap belt only, or shoulder belt under the arm, for example, while belt misrouting included lap belt on the abdomen, shoulder belt above the breasts, or shoulder belt on the neck. The literature review also highlighted the lack of information on the prevalence of belt misuse and misrouting, partially due to assessment complexity. The literature review also identified various methods used to assess misuse/misrouting including testimonies and physical evidence on the occupant (i.e., belt marks/ injury pattern) and on the vehicle interior and/or restraint system (i.e., loading marks). The second objective was to develop an identification framework based on these methods. The framework included measuring webbing lengths and seat belt hardware angles that can be used in conjunction with surrogate studies and dynamic tests. The third objective was to evaluate the framework using 8 field accidents. In addition, a fourth objective was to conduct a surrogate study with a female volunteer for each of the 9 belt misuse/misrouting scenarios identified in the literature. The webbing lengths and angles at the hardware were measured. In conclusion, identifying belt misuse is complex. Testimonies, physical evidence, and/or injury patterns invoke uncertainties that then needs to be validated with surrogate work and/or dynamic testing. Newer technologies such as video footage from in-vehicle cameras have the potential to provide additional data.