Roof Crush Accidents and Spinal Cord Injury
Highway traffic accident data collected by the National Highway Traffic Administration (NHTSA) reveal that passenger vehicle rollover accidents resulted in 32% of all highway accident fatalities between 1995 and 1999 but only accounted for 3-4% of all types of accidents where the vehicle was damaged severely enough to require towing. An occupant of a vehicle involved in a highway crash is therefore 13 times more likely to die from their injuries if the vehicle rolls over during the accident.
The risk of serious non-fatal injury is also higher for rollover accidents, representing 18% of all serious injuries sustained in highway accidents during the same period. Occupants of vehicles that rolled over during an accident are 6 times more likely to suffer a serious injury when compared to all other types of accidents.
During the 1988 to 1999 period approximately 23,376 light-duty vehicle occupants per year sustained serious or fatal injuries during rollover accidents. Of these, 7460 or 32% sustained at least one injury due to contact with the roof, and contact with the roof is how 89% of these victims received their most serious injuries. A full 93%, or 6,934 rollover vehicle occupants per year, were seriously or fatally injured from the roof being crushed during the accident. Half of these victims were wearing seatbelts at the time of the accident, but studies examining the risk of head and neck injury due to the roof being crushed revealed a greater risk if restrained within the vehicle.
The location of the roof crush tends to occur more often on the outside arc or point furthest from the pivot point of the rollover (42% vs. 26.3%), and occupants exposed to the torque forces generated on the outside of the arc of rotation are more likely to sustain fatal injuries (0.38% vs. 0.23%). The risk for sustaining fatal injuries was increased substantially if the occupants were exposed to outside arc forces in an SUV (0.99% vs. 0.19%). In 2007, 59% of fatal injuries sustained by SUV occupants occurred during a rollover accident. By comparison, 46% and 25% of passengers in light-duty pickup trucks and cars, respectively, received fatal injuries during rollover accidents. The risk for suffering a fatal injury during a rollover accident therefore depends on the type of vehicle involved, whether restraints are utilized, and how close the occupants are sitting to the outside arc of the rollover.
The strength of the roof in relation to the weight of the vehicle is a major factor determining whether occupants will sustain a serious injury during a rollover accident. The stronger the roof, the less likely that it will intrude into the passenger compartment. The velocity of roof intrusion will also be slower the stronger the roof is. The velocity of the head strike matters as well and current understanding suggests a velocity over 7 mph will result in serious injury, and a velocity over 10 mph will result in fatal injuries. These estimates are influenced by the age and gender of the occupants.
Current federal standards (FMVSS216) require light-duty vehicles to withstand 1-1/2 times the weight of the vehicle. This corresponds to a Strength to Weight Ratio (SWR) of 1.5. The SWR for SUVs was 1.6 to 3.1 during the 1993 to 2001 production years. Laboratory testing of several American production vehicles from this period revealed an SWR between 2.5 and 3.5 was required to prevent significant roof intrusion into the passenger compartment, depending on which test was used.
Controversy surrounded the actual cause of head and neck injuries suffered in roof crush accidents for several decades, but this has been resolved. A recent study measuring the forces impacting cervical sensors in crash test dummies revealed diminished headroom at the outer arc of the rollover is the most likely cause of spinal injury. A recent study by the NHTSA, which relied on accident data collected between 1997 and 2005, revealed a statistically significant positive relationship between head, neck, and face injury severity and the degree of vertical intrusion of the roof into the passenger compartment.
It seems clear that strengthening the roofs of vehicles would save many lives and prevent thousands of serious head and spinal cord injuries that result in paralysis, hemiplegia, paraplegia, and quadraplegia/tetraplegia, but the American auto industry seems unwilling to change in the face of this overwhelming evidence. Until then, spinal cord injury lawyers will continue to have a steady supply of clients.
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