Head Accelerations and Concussion Risks in Low-to-Moderate–Speed Rear-End Collisions

Recent studies have investigated head injury metrics, including mild traumatic brain injury (mTBI), or concussion risks, in low- to moderate-speed rear-end collisions, with linear and angular head accelerations contributing to the risk of developing a concussion. The present study analyzes head acceleration values in rear-end collisions at an impact severity of 5–30 km/h delta-V. Biomechanical data was obtained from HIII 50th percentile male anthropomorphic test devices (ATDs) seated in the target subject vehicles and utilizing safety restraints and head rests. Concussion risks were calculated from resultant linear and angular head accelerations recorded in the ATDs, and a linear regression model was used to determine what, if any, relationship existed between these head injury metrics and impact severity. The results indicate that there is a significant and positive relationship between head acceleration metrics and impact severity, particularly in the sagittal plane, with F-values < 0.05. Additionally, there is a positive relationship between concussion risks and impact severity, but results also determine that the concussion risks are less than 0.1% and indistinguishable from 0 at this range of impact severity. An outlier test that included head impact with a rear-seated passenger ATD yielded a less than 2% risk of sustaining a concussion. It is expected that the results of this study will aid in accident reconstruction and biomechanical analysis for restrained occupants involved in low- to moderate-speed rear-end collisions.