Why is this important to accident reconstructionists? Because the insurance industry has declared that the presence of injury without significant property damage is an indicator of fraud (see Insurance Research Council report, 2000). Many insurance companies (e.g., Allstate) will put their fraud investigation units into action immediately when there is a claim of injury with $1000 or less property damage. Therefore, for those AR's hired by the defense in motor vehicle tort cases as expert witnesses, it seems prudent to be aware of the fact that vehicle damage is not an indication of occupant injury. AR's who minimize forces to occupants by looking only at vehicle accelerations and delta V's as "predictors" of injury miss the fact that occupant accelerations and kinematics are highly individualized and often much higher and very different than the vehicle, respectively.
I am reminded of these points when I re-read Rusty Haight's comments from TARO 2000 on low speed collisions. Mr. Haight said (among other things):
“Based on what I've seen in hundreds of [crash] tests, repeated tests with men and women in a variety of ages, I would stand by the conclusion that ‘a reasonably healthy human occupant can withstand a rear impact with a change in velocity of 8 km/h [5 mph] without sustaining significant injury, assuming the presence of a head restraint and a reasonably normal initial seating position’. It just doesn't happen in modern cars with (the conditions outlined in the statement) but I will allow for the possibility when other conditions exist which would provide a potential for injury (lack of headrest, substantially out of position and others)”.
What is Mr. Haight saying, really? That reasonably healthy humans can get rear-ended at 5 mph without significant injury… as long as there is an effective head restraint and a “reasonably normal” position in the seat. Well, there are two problems with that statement right there. IIHS has looked at head restraints and found them to be utterly lacking, although improved (October 4, 2001 press release). To use the IIHS standards, about half (46%) of the head restraints in 2001 model cars are “marginal” or “poor”. In 1999 cars, 40% are poor and 28% marginal. In 1997 cars, 70% are poor and 18% marginal. In 1995 cars, 82% were rated poor and 11% marginal. So Mr. Haight’s assertion that crash testing mimics the real world is absurd.
And even if most cars had adequate head restraints, most drivers do not have their head restraints positioned properly, even if they are fortunate to have an “acceptable” head restraint (whatever that is). Most drivers are not driving 2001 model cars yet.
The second problem with Mr. Haight’s statement is that he must assume a “reasonably normal seating position” when they are struck. That is also an absurd notion for real world drivers. Mr. Haight also compared crash testing vs. epidemiology and stated that crash testing has a better hold on reality. But he forgets something very important: epidemiology looks at drivers in the real world with real injuries, and crash testing does not. Physicians taking clinical histories of auto accidents ask patients about head position, body position, traffic situations during the crash, etc. While I agree that patients are often wrong about distances, speeds and many other crash parameters, I believe that they are often correct about their head position at the time of the crash, their body position, their head restraint position, the distance between their head and their head restraint (backset), and many other human factors during the collision.
The real world of crashes isn’t the world of human volunteer crash tests, to be sure. So a “reasonably