The Traffic Accident Reconstruction Origin -ARnews-

Speedometer "slap" marks as indicator of impact speed

D. E. Fitzsimmons (deafitz@aol.com)
Tue, 17 Feb 1998 12:46:32 -0500 (EST)

I am preparing for the prosecution of a vehicular homicide case. The incident involves the collision of the front of a passenger vehicle with the rear of a parked tractor-trailer. No skid marks preceded the impact. The impact was straight-on.

Analysis of the crush damage yielded an estimated speed of 40+ m.p.h.

The vehicle's speedometer was frozen at 53 m.p.h. When the entire instument panel was removed from the vehicle and examined at the laboratory under ultraviolet light, two speedometer needle "slap" marks were observed. One mark was at 48 m.p.h. and the other was at 51 m.p.h.

Similar "slap" marks were found on the tachometer. However, since the vehicle has an automatic transmission with torque converter, these marks are apparently not useful to establish impact speed.

I am looking for any insight into the reliability of these marks as indicators of impact speed. I am also looking for the results of any research which has been conducted in this area.

My business address is:

Deputy Dist. Atty. Daniel Fitzsimmons
Office of the District Attorney
401 County Courthouse
Pittsburgh, PA 15219

My business telephone number is: (412) 350-5656.

My home e-mail address is: deafitz@aol.com.

my fax number is: (412) 350-3312.

Thanks for any assistance,
Dan Fitzsimmons

D. E. Fitzsimmons
deafitz@aol.com

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