Question

Difficulty: MediumSpeed and Road Conditions

While transporting freight on a divided highway, an operator observes that the ambient temperature has dropped to freezing (32∘F32^\circ\text{F}) and slush is turning into clear ice across the roadway surface. The route ahead features an upcoming curved interchange ramp. What is the safest combination of speed and vehicle control actions for the operator to take?

  1. A
    Engage the engine retarder at maximum power before the ramp so the drive wheels slow the vehicle without applying the foot brake.
  2. Reduce speed to a crawl well before reaching the ramp and ensure the engine retarder remains deactivated.Answer
  3. C
    Maintain highway speed until entering the curved ramp, then apply continuous service braking throughout the turn.
  4. D
    Delay deceleration until reaching the midpoint of the ramp, assuming normal braking distances apply once the tractor is on the curve.

Answer

Reduce speed to a crawl well before reaching the ramp and ensure the engine retarder remains deactivated.
According to official CDL safety regulations, when road surfaces turn to ice, drivers must reduce vehicle speed to a crawl and stop driving as soon as it is safe to do so. Furthermore, engine retarders must be turned off whenever driving on wet, icy, or snow-covered roads to avoid drive-wheel lockup, and all necessary deceleration must occur in a straight line before entering any curve.

Step-by-Step Solution

1
Assess the roadway surface condition and determine the required speed reduction.
Recognize that icy road surfaces demand reducing vehicle speed to a crawl rather than standard highway speeds.
Icy pavement reduces tire-road friction to near zero, making standard speed limits extremely dangerous.
2
Adjust vehicle retarder controls and timing of speed adjustments.
Deactivate auxiliary engine braking systems and complete all deceleration before steering into the curve.
Engine retarders can lock drive wheels on slick surfaces, and braking within a curve induces fatal traction loss.

Key Concept

Speed reduction to a crawl on ice and deactivating engine retarders prior to negotiating curves.
Estimated Time:1m 0s
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