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Roll over at Mount Whitney

 Please be aware that driving on graded dirt roads can be very dangerous. Traction and directional stability are marginal on dirt - even in 4WD. The gravel under the tires acts like small ball bearings.

Slightest steering input can result in fishtailing and loss of control. Also: Immediately after stepping on the brake the wheels will lock up unless you have ABS. Slowing down when approaching a turn is only natural, but braking and initiating a turn can lead to severe fishtailing and on a dirt road. It is almost impossible to regain control. The vehicle will eventually get sideways and roll over. The result can be seen below.
Stability control would have been able to prevent fishtailing and rolling.
   I was driving downhill on a dirt road below Mount Whitney in California. Speed was about 50 mph (certainly too fast) when I tapped the brakes to slow down for a slight turn. The vehicle started fishtailing immediately. My brain told me: "Get off the brake and give it a little gas to straighten out." My stomach seemed to have a shorter connection to my foot on the brake and made it brake harder. This proved only once more that gut feelings and piloting a car do not work well together.

Braking harder increased the fishtailing and when the vehicle got sideways far enough it rolled over. In fact, it made 3 1/4 rolls.

Many newer vehicles have ESC, which would have prevented this accident.

Please notice that on dirt roads ABS will lengthen the stopping distance dramatically.

Always remember that ABS does not work with part time 4WD

Taking ABS a step further: BAS

Stability control, the wonderful feature to prevent fishtailig: ESC or ESP



Using ABS sensors for traction control:
4ETS


© 1998-2007 Harald Pietschmann