Injury mechanisms and severity in narrow offset frontal impacts

Current standard frontal crash tests include full frontal or 40% offset. Frontal impacts with offsets less than 40% and corner impacts have received little attention. Because of the limited engagement of vehicle structures that would permit less energy dissipation, these crashes have the potential for severe trauma to the near-side occupant. Narrow offset and corner-impact crashes under a frontal impact classification were analyzed using data obtained from the United States Department of Transportation National Highway Traffic Safety Administration crash databases: Crash Injury Research and Engineering Network (CIREN) and the National Automotive Sampling System (NASS) 2000-2006. A subset of crashes that could be defined clearly as narrow offset crashes were then examined. The Collision Damage Classification (CDC) classification was used to obtain only crashes with a "FLEE" code for drivers and a "FREE" code for right front passengers. These codes were used to separate out crashes that had bumper and lower vehicle engagement and less than 41 cm of front vehicle damage. The NASS data indicated that corner impacts ("Y" and "Z" type) and narrow overlap ("L" and "R" type) constitute 26 % each of all frontal impacts. When occupants were severely injured in frontal crashes 20 % of the occupants were in "L" and "R" type crashes and 31 % were in "Y" and "Z" type crashes. The percentage of near side "FLEE" and "FREE" crash occupants with severe injuries by body region demonstrated that head, thorax, upper, and lower extremity injuries dominate the data set. For the 71 CIREN cases, lower extremity injuries dominated. The injury severity score did not correlate well with assumed severity parameters like extent of crush and delta-V, however, crashes with extent zones 2-5 had a greater percentage of occupants with chest and spine injuries than crashes with extent zones 6-9. Vehicle rotation after front impact in extent zone 2-5 crashes may be influential in airbag effectiveness.