Pedestrian Vaults: Humans Going Ballistic
Pedestrian Vaults: Humans Going Ballistic
by George M. Bonnett, JD
The pedestrian vault: complicated and controversial – the perfect topic for examination.
It sometimes seems that everyone involved with crash reconstruction has discovered a formula or formula variant
computing pedestrian vault speed and there are at least a half-dozen computer programs that primarily
deal with pedestrian and/or bicycle vaults. In this article, Pedestrian Vaults: Humans Going Ballistic,
George Bonnett offers you a solution to simplify the process.
Reconstructionists are aware that for any given launch angle and friction coefficient between the
pedestrian and the surface over which he or she is sliding, the vault and slide components of the
pedestrian vault are tied to each other. If the launch angle and surface friction are known for any given
throw distance, then solving for the vault speed of the pedestrian is simply a matter of doing the
mathematics. If the throw distance is kept as a constant, then the only way the eighty plus currently
published pedestrian formulae can arrive at different solutions is by varying either the launch angle or
the friction factor of the pedestrian. And as every pedestrian vault formula requires an input of the
friction factor, the only remaining variable is the launch angle.
Because this fundamental relationship is based
on physics principles, the only real difference between all of the existing
pedestrian formulae is the assumed launch angle. If a launch angle is known
or assumed, the solution can be found using four basic equations found in
any physics book. The author shows you how to work through the process
step-by step to arrive at the correct solution to a sample problem. He then
goes on to demonstrate the use of Finite Difference Analysis to solve for
the uncertainty value of the computations.
George Bonnett is a combat proven Marine Corps aviator turned police officer turned attorney turned
crash reconstructionist turned software developer and author (REC-TEC). His whole life has depended
on minute attention to detail. In this article, he gives you the benefit of his years of experience.
Specifications: 20 pages; 8½”x11"; saddle stitched; Publisher: IPTM (October 2005)
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