The Traffic Accident Reconstruction Origin -ARnews-


Re: Speedometer Locked in Position Following a Collision

Duane R. Meyers (DMeyers372@msn.com)
Sun, 29 Mar 1998 21:55:17 -0500 (EST)

One of my co-workers has been examining speedometer back plates for needle slap for some time. He has been keeping a log of the findings including the type of needle, it's length and thickness, etc. It appears that the properties of the needle as well as the acceleration rate the vehicle has undergone are key factors in the analysis. He has performed several examinations for me as well as others. I can recall one recently where the marking on the backplate corroborated my momentum analysis.

His methodology is the use of infrared film and either filters or solely an infrared light source. This has nothing to do with the position the needle is found in during a post-crash investigation.

I agree with all who view this data with skepticism. I too would not rely on this as conclusive. However, I believe there is a relationship with the needle, backplate, distance from backplate, and rate of acceleration the needle and backplate are undergoing. Perhaps all who are performing these analyses could share information and develop a database. If interested, I can provide you with contact information for my co-worker.

Duane Meyers
Wisconsin State Patrol
Duane R. Meyers
DMeyers372@msn.com


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