The Traffic Accident Reconstruction Origin -ARnews-

Re: Pedestrian Ride Times

Jerry Eubanks (JerryEubanks@worldnet.att.net)
Fri, 25 Jul 1997 17:47:17 -0400 (EDT)

Ride times of pedestrian is dependant on two factors, assuming the ped doesn't get hung up on the windshield.

Assume the vehicle is traveling at heading of zero degrees. The pedestrian is traveling at some angle to the vehicle. The velocity across the vehicle is setup based on the pedestrian velocity and then the angle the pedestrian was walking at impact. Do not exceed 90 degrees for the path of the pedestrian,in otherwords if the pedestrian is moving in line with the vehicle whether it is going towards or away from the vehicle at impact then the pedestrian's angle would be zero degrees. If the pedestrian is moving at a right angle to the vehicle then the pedestrian's angle would be 90 degrees no matter which direction driver's to passenger or passenger to driver's side of the vehicle.
The equation for detemrine the Velocity of the pedestrian across the vehicle is V across = V ped * sin (theta) where V ped is the pedestrian walking velocity and the sine (theta) is the sine of the angle between the vehicle and the pedestrian)not to exceed 90 degrees. If you then determine the distance d hood where d hood is the distance from the inital contact of the pedestrian on the car laterally to the side of the car the pedestrian rolled off. This is not the distance along the travel path but the distance across the front of the hood. To determine the time take the d hood value divide by V across value. For instance assume the following: The angle of the ped to the car was 45 degrees. And assume that d hood value is 2 feet. Assume that the ped is walking at 5 fps. V across becomes 5 fps * sine (45) = 5 fps * .707 = 3.5 fps is the value for V across. To determine the time for the pedestrian on the hood (t hood), we find that T hood = D hood / V across. And in
this example
T hood = 2 ft / 3.5 fps = 0.57 seconds. If you want to look at a paper on this subject get SAE 921591 and look at the euation on the right column of page 47 and you will see the first half of the "B" coefficient in a quadratic equation as the T hood value.

While I can't advise anything about the pedestrian being hung up on the car I would tell you in probably less than 5 percent of the crash tests that Rusty Haight and I have done do we get the ped or bike rider to hang up. If the pedestrian did validly get hung up on the car then no pedestrian equation will work.

If you have any questions, I have put my e-mail address so you can get hold of me.

Jerry Eubanks
JerryEubanks@worldnet.att.net

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