After an accident occurs,
everyone wants someone to tell them what happened. But
in fatal car accidents, sometimes nobody is left to
tell. So we are left with just the evidence on scene.
A big piece of that evidence is the tire skidmarks left
on the roadway. In a majority of accidents, there are
usually some types of tire marks left by the vehicle(s)
involved. But there are different ways of solving speeds
depending on the type of tire marks left behind. Is
the evidence skidmarks, yawmarks, acceleration scuffs,
flat tire marks, or imprints? Thorn Consulting Services
has extensive experience in recognizing and determining
the speeds of vehicles from the aforementioned marks.
It is well known that when a driver applies the brakes
really hard, the wheels will lock. As a result, the
vehicle will slide and usually leave evidence of skidmarks
on the roadway. The length of these skids is an indication
of the speed of the vehicle. Two factors are important
when calculating speed from skidmarks: 1) the distance
the vehicle slid and 2) the coefficient of friction
or drag factor between the road and the tires of the
If you know or have an estimate of how far a vehicle
slid and the coefficient of friction, click on the above
Skidmark Chart to find its speed. The chart assumes
100 percent braking efficiency on a level surface.
Download a Sample Speed From Skidmarks Chart. You will
need to have Adobe Reader on your computer to view this
file - download the FREE Acrobat Reader if
you do not have it. It's very quick and easy.