The Traffic Accident Reconstruction Origin -ARnews-

Re: Low light skid mark identification

Ed Livesay (elivesay@alltel.net)
Thu, 31 Oct 1996 09:24:45 -0500 (EST)

Dear Mike:

I'd heard of a technique for visually determining the impending shadow etc. (beginning)
of a skid via the use of an ultraviolet light. I finally had an occasion to try
the idea and it was useful. In short the investigator drapes a blanket over him/herself
while in the area of the beginning of the skids. For obvious reasons extreme care must
be taken with regard to the investigator's safety (i.e. plenty of help with any existing
traffic etc.) The blanket simply screens out any residual ambient lighting. The investigator
employs a portable ultraviolet (a blacklight or Wood's light) lamp to scan the
road surface. The tiny specks of dirt sand etc. more often than not are illuminated
much like the lint on a dark shirt as one enters a bar at which a black light is used
to illuminate a paid ink-stamp on the patron's hand (or so I've been told.....) The
portion of the roadway over which a tire has recently skidded reveals a fairly overt
lack of such particles or a lesser density of such specks. Sometimes the particles have
visibly been disturbed by the tire as it abraids against the surface. I have found the
technique fairly useable in finding the true beginning of a skid and it has been useful
in establishing the existence of tire marks from vehicles equipped with ABS brakes.
Ed Livesay
elivesay@alltel.net

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