A CONTINUOUS VIDEO RECORDING SYSTEM ON A LAP-BELT EQUIPPED SCHOOL BUS: REAL-WORLD OCCUPANT KINEMATICS AND INJURIES DURING A SEVERE SIDE IMPACT CRASH

摘要

A loaded truck-tractor semitrailer severely impacted the side of a lap-belt-equipped large school bus in which 30 students, age 5 to 11 years, were riding. The crash investigation obtained on-board video and audio from the school bus recording system, which had four active cameras that recorded at 15 frames per second. A total of 55 minutes 39 seconds of video and audio was obtained, including over 15 minutes after the bus came to final rest. Qualitative descriptions of occupant motion during the crash sequence were documented based on the time sequence of vehicle motion, including kinematics of lap-belted pediatric occupants, occupant-tooccupant interactions, and occupant-to-vehicle interactions. Further, quantitative measurements of occupant motion were performed by tracking visible body regions such as the head or center of the pelvis using commercially available motion analysis software. Occupant injuries were coded using hospital medical records and according to the Abbreviated Injury Scale 2008 manual. Injury severity was higher in the rear of the bus near the region of impact, maximum intrusion, and maximum lateral accelerations. The injury severity scores (ISS) ranged from 1 to 6 in the front of the bus and from 1 to 57 at the rear, including the one student seated at the rear of the bus who was fatally injured. Head injuries included several mild to moderate traumatic brain injuries. Lateral head translations and velocities were evaluated. The lateral head displacements toward the impacted side in the front of the bus were similar to those in the rear during the initial impact, but the head displacements for occupants in the rear of the bus were greater during the secondary and tertiary rebound motions toward alternating sides of the bus. Lateral head velocities relative to the bus interior were generally almost twice as high in the rear of the bus as in the front. In addition, the magnitude of whole body pediatric occupant motion in the absence of injury was notable. Further, loss of consciousness negatively affected occupants' ability to self-evacuate, even when subjects regained consciousness. The qualitative and quantitative descriptions represent the first time that lap-belted school bus pediatric occupant motion during a crash has been documented from continuous onboard video recordings. This unique data source allows the rare correlation of occupant kinematics with crash severity and injury outcomes in living humans.