Evaluation of vehicle interior head impacts for the forensic analysis of MAIS head injury risk

In the field of forensic collision reconstruction, in order to analyze the vehicular/mechanical component(s) of a dynamic impact, the overall severity of the crash event is typically assessed by quantifying the change in velocity (Delta V) of the vehicle and/or the occupant. Often, in a vehicle impact, there is forensic evidence present on the vehicle interior to indicate the location of a head-to-component impact. If a head injury has occurred as a result of the impact, there is often an inquiry made regarding the likely vehicle impact velocity required to produce a specific head injury. The “Head Injury Criterion” (HIC) is a widely-used parameter related to the physiology of brain injury risk. Unfortunately, physical laboratory testing for the forensic calculation of an impact-specific HIC value is often not feasible. In order to forensically evaluate contributing factors and mitigation for a real-world head-to-surface impact, an assessment of the impacted surface characteristics is paradigm. Subsequent to the introduction of Federal Motor Vehicle Safety Standard (FMVSS) 201 for head impact protection in vehicle interior impacts, vehicles have been designed with safety features to minimize head injury risk. However, vehicles manufactured prior to FMVSS 201 have interior structures which may be harmful if impacted at relatively low impact speeds. This paper provides thorough documentation of data associated with varying head-to-surface vehicle interior impacts. This study attempts to quantify the injury likelihood for individual interior impact observed in laboratory experiments so that values can be applied when forensically investigating impacts in the real world.