Determination of Seatbelt Use Following a Crash 2020-01-0643
When investigating a vehicle crash, the issue of seatbelt usage is frequently part of the information needed to perform an analysis related to occupant kinematics or injury. A physical inspection of the vehicle is the preferred method to investigate seatbelt usage. However, if the vehicle is no longer available or the condition has changed since the time of the crash, preventing analysis of seatbelt usage by an occupant, the investigator must rely on other available evidence to assess seatbelt usage by an occupant. This other evidence includes the police report, scene photographs, physical marks on the occupant noted in medical records and witness statements. More recently, event data recorders (EDR) may provide data regarding seatbelt status for front seat occupants, and occasionally, rear seat occupants. However, the EDR data must have been previously recovered or the vehicle must be available.
In cases where the available data is very limited or includes only subjective data, some investigators have used the post-crash seatbelt position to determine seatbelt usage at the time of the impact. The theory is if the seatbelt is retracted or stowed post-crash, it was not in use at the time of the collision. The validity of this theory was investigated using EDR data from the NHTSA Crash Investigation Sampling System (CISS) as well as EDR files collected during in-house crash investigations. Photographic documentation of the post-crash seatbelt position was compared to EDR data to determine if post-crash seatbelt position can be used to determine seatbelt usage at the time of impact. Additionally, EDR seatbelt usage was compared to police reported seatbelt usage.