The Traffic Accident Reconstruction Origin -ARnews-

Re: Pedestrian Accident Reconstruction

W. R. Rusty Haight (RustyHaight@worldnet.att.net)
Tue, 18 Nov 1997 13:50:58 -0500 (EST)

Joseph, ARE YOU KIDDING or was there a typo (or 10) in the post? I've done one or two ped and bicyclist crash tests here of late and what you're saying not only goes against the grain of physics but logic as well. There are essentially two general types of pedestrian trajectories as a result of a collision with (by) a car: (1) a forward projection and (2) one of the wrap type trajectories. In a forward projection, the body's COM is below the leading edge of the hood of the striking vehicle and the body is accelerated to very closely 100% of the striking vehicle's speed. This would be the "classic school bus to ped" collision with pre-impact braking. In the other type - the wrap family - the impact is below the ped's COM and the ped is accelerated in the direction of the car, but to a speed less than that 100% we see in forward projection cases. In your north-south example, even if we assume the ped to be walking south against the car at impact, there overwelming vector is north
(with the car) and, even if the car DRIVES THROUGH and UNDER the ped (which is essentially the roof vault described) - the ped's COM will go north WITH the car every time - sometimes more (longer) than others depending largely on the COM to leading edge relationship. Recommend you rethink that post, you DO NOT need common velocity for the body to move the same direciton as the car and, in a roof vault (wrap) while you may not get 100% of the striking car's speed, you will most assuredly get the body going essentially the same direction as the striking car.
W. R. Rusty Haight
RustyHaight@worldnet.att.net

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