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[ Drag Factors ] [ Skid Speed Equation ] [ Skid Mark Evidence ]
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These tables provide the distance a car
will skid given specific criteria. The distance is the average skid distance
of all four wheels locked through the skid on a level road surface.
These values are for guidance only. The skid distances presented do not
account for speed losses from impacts or other events at any point in the
skid. The value ranges are nominal and may not apply to any specific
situation. Accurate drag factor values are best determined by on-site
testing.
Ranges for drag factors for different
types of road surfaces:
Concrete, new, sharp, dry - 0.80 to
1.20
Concrete, traveled, dry - 0.60 to 0.80
Asphalt, new, sharp, dry - 0.80 to 1.20
Asphalt, traveled, dry - 0.60 to 0.80
Gravel, loose, dry - 0.40 to 0.70
Snow, packed - 0.30 to 0.55
Snow, loose - 0.10 to 0.25
Ice, smooth - 0.10 to 0.25
DRAG FACTOR = 0.10
|
SPEED (MPH) |
SKID DISTANCE (FEET) |
|
20 |
133 |
|
30 |
300 |
|
40 |
533 |
|
50 |
833 |
|
60 |
1,200 |
|
70 |
1,633 |
|
80 |
2,133 |
DRAG FACTOR = 0.30
|
SPEED (MPH) |
SKID DISTANCE (FEET) |
|
20 |
44 |
|
30 |
100 |
|
40 |
177 |
|
50 |
277 |
|
60 |
400 |
|
70 |
544 |
|
80 |
711 |
DRAG FACTOR = 0.50
|
SPEED (MPH) |
SKID DISTANCE (FEET) |
|
20 |
26 |
|
30 |
60 |
|
40 |
106 |
|
50 |
166 |
|
60 |
240 |
|
70 |
326 |
|
80 |
426 |
DRAG FACTOR = 0.70
|
SPEED (MPH) |
SKID DISTANCE (FEET) |
|
20 |
19 |
|
30 |
42 |
|
40 |
76 |
|
50 |
119 |
|
60 |
171 |
|
70 |
233 |
|
80 |
304 |
DRAG FACTOR = 0.80
|
SPEED (MPH) |
SKID DISTANCE (FEET) |
|
20 |
16 |
|
30 |
37 |
|
40 |
66 |
|
50 |
104 |
|
60 |
150 |
|
70 |
204 |
|
80 |
266 |
DRAG FACTOR = 0.90
|
SPEED (MPH) |
SKID DISTANCE (FEET) |
|
20 |
14 |
|
30 |
33 |
|
40 |
59 |
|
50 |
92 |
|
60 |
133 |
|
70 |
181 |
|
80 |
237 |
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