Abstract: The crash safety of four-door sedans in near-side impacts was investigated with respect to the
vehicle model year and the occupant seating position to predict serious injury risks, using the National Highway
Traffic Safety Administration (NHTSA) New Car Assessment Program (NCAP) moving deformable barrier (MDB)
tests database as the data sources. The test vehicle geometrical characteristics and the crush deformation
were summarized with the head injury criteria (HIC), the thoracic trauma index (TTI), and the peak pelvis lateral
acceleration (PPLA) used to evaluate serious injury risks for different body regions of occupants. The results
show that these injury criteria all decrease with increasing vehicle model year for both front and rear seat
occupants. Much higher risks of serious head and thoracic injury occur for rear seat occupants compared with
the front seat occupants for newer vehicle models. Restraint effectiveness is closely related to occupant seating
positions. Therefore, the head and thoracic injury mechanism and countermeasures should be emphasized for
rear seat occupants.

Key words: automotive crash safety, near-side collision, rear seat, head injury criteria (HIC), thoracic trauma
index (TTI), peak pelvis lateral acceleration (PPLA), moving deformable barrier (MDB), New Car
Assessment Program (NCAP)