The Traffic Accident Reconstruction Origin -ARnews-

Re: Drag Sleds

John Serth jr. (73553.3314@compuserve.com)
Mon, 15 Apr 1996 07:54:10 -0400 (EDT)

I do understand that drag sleds have enjoyed widespread use and
that in many areas they are the test of choice for police officers.

However I do agree with you that perhaps the numbers are suspect.
AASHTO has said for decades that coefficient of friction is speed
dependent. Shurly few accidents requiring a drag sled ocure at the
speeds that the concrete filled tire can be dragged. Coefficient of
friction may be dependent on tire preshure. What is the contact area
under the concrete wheel? It appears that there is a difference
between the tire which is riding on a film of melting and burning
road and/or pavement and a drag sled which leaves no skid marks.
SAE paper 930665 found that the drag sled did not obtain the same
f as other methods. I have been told by an attorney that the use of
a drag sled was thrown out of court in New York.

I would like to be able to use a simple test. However I have many
questions about the concrete filled drag sled. Any comments?
John Serth jr.
73553 3314@compuserve.com

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