School bus transportation remains the safest form of ground transportation in the US. As CPS experts know, getting to and from the bus is actually more dangerous than traveling by bus. Because injuries and fatalities involving school bus crashes are rare, when they do happen, it’s all the more important to understand the mechanisms of injury to child passengers. Recently my CIRP@CHOP colleague Kristy Arbogast, PhD and I, along with Richard Kent, PhD from the University of Virginia, were presented with a unique opportunity by the National Transportation Safety Board (NTSB) to assist with an investigation into a fatal 2012 school bus crash in Port St. Lucie, FL.
The school bus was equipped with video monitoring, providing a rare first-hand perspective into the crash and its immediate aftermath. We were tasked with using the video and medical records of the injured children to understand the mechanisms and sequela of injury from both a biomechanical and clinical perspective. In addition to the lap belts the children were wearing, school buses are designed with passive occupant protection in the form of compartmentalization, designed to protect children in front or rear crashes using energy-absorbent seat backs and narrow spacing. However, the crash we investigated was side-impact, mitigating the protective effect of compartmentalization and resulting in numerous occupant injuries. Using supplemental injury coding based on the Abbreviated Injury Scale (AIS) we described and ranked injuries from the medical records by severity. The video provided a rare opportunity to go beyond the information in the medical records to actually see the injuries as they happened. This allowed us to quantify certain injury aspects that are almost always estimated, such as loss of consciousness, as well as see firsthand the contacts between the occupants and the vehicle interior that may have led to injury. The resulting report provides a uniquely comprehensive assessment of the biomechanical responses of the child occupants to the crash forces and the mechanisms of their injuries.
In a presentation last week, the NTSB provided recommendations for safety improvements primarily based on a school bus crash in Chesterfield, NJ as well as the one in Florida we studied (coincidentally, Florida and New Jersey are two of only six US states that require lap belts on school buses). Included among the many recommendations are advocating for lap and shoulder belts on school buses and developing performance standards for school buses that address passenger protection for sidewalls, sidewall components, and seat frames – contact locations for many of the head injuries. Hopefully the families of the injured children can take some solace in knowing the NTSB and its safety partners are dedicated to studying these crashes in detail and using the information to advance optimal protection for child passengers.