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Zorluk: KolaySpeed and Road Conditions

While driving on a rural two-lane highway during a winter storm, a commercial driver encounters packed snow covering the roadway. If the normal safe speed for dry conditions is 40 mph40\text{ mph}, what is the proper speed adjustment required according to commercial driving safety guidelines?

  1. A
    Maintain speed at 40 mph40\text{ mph} but switch the engine retarder to maximum power to stabilize the drive wheels.
  2. B
    Maintain 40 mph40\text{ mph} through straight sections and apply firm service braking after entering any upcoming curve.
  3. Reduce vehicle speed by at least half, slowing down to 20 mph20\text{ mph} or lower.Cevap
  4. D
    Reduce speed by only 5 mph5\text{ mph}, assuming total stopping distance is determined strictly by mechanical braking distance.

Cevap

Reduce vehicle speed by at least half, slowing down to 20 mph20\text{ mph} or lower.
According to official commercial driving standards, drivers must reduce their speed by about one-third on wet roads and by at least one-half on packed snow. When normal safe dry speed is 40 mph40\text{ mph}, cutting speed by at least half yields a target speed of 20 mph20\text{ mph} or lower, providing essential traction control and stopping margins.

Adım Adım Çözüm

1
Identify the roadway condition and apply the standard CDL speed reduction rule for packed snow.
The roadway is covered in packed snow, which requires reducing speed by at least one-half (12\frac{1}{2}).
Packed snow drastically reduces the coefficient of friction between the tires and the road surface.
2
Calculate the safe operating speed based on the baseline dry speed of 40 mph40\text{ mph}.
40 mph×12=20 mph40\text{ mph} \times \frac{1}{2} = 20\text{ mph} (or less).
Cutting speed in half provides the necessary margin of safety and accounts for extended stopping distances on snow.

Anahtar Kavram

Speed reduction guidelines for packed snow conditions
Tahmini Süre:45s
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Konular

Speed and Road Conditions

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