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Difficulty: EasyDriving in Fog

During morning operations, patchy ground fog begins settling across the highway, leaving the pavement damp and visibility reduced. Which of the following actions should the driver take to maintain safe control?

  1. A
    Engage the engine retarder at full power to assist in decelerating without applying the service brakes.
  2. Turn off the engine retarder, reduce speed, and adjust travel so the vehicle can stop within the distance clearly visible ahead.Answer
  3. C
    Maintain posted travel speeds by closely following the taillights of a leading vehicle for guidance.
  4. D
    Rely on standard dry-road braking distances without accounting for driver perception and reaction time in reduced sight conditions.

Answer

Turn off the engine retarder, reduce speed, and adjust travel so the vehicle can stop within the distance clearly visible ahead.
The correct action is to turn off the engine retarder and reduce speed so that the commercial vehicle can safely stop within the distance visible ahead. Moisture from fog condenses on the roadway, making it slick; applying an engine retarder on slippery pavement can cause the drive wheels to lose traction and trigger a jackknife or skid.

Step-by-Step Solution

1
Assess the traction and visibility hazard posed by foggy conditions.
Identify that moisture on the pavement creates slippery road surfaces and fog reduces sight distance.
Fog produces condensation on the road surface and restricts forward vision.
2
Determine the proper retarder and speed management adjustments.
Disengage the retarder to prevent drive-wheel skids and slow down to maintain stopping capability within sight distance.
Commercial motor vehicle safety guidelines require disabling retarders on wet roads and driving at a speed that allows stopping within visible range.

Key Concept

Disengaging retarders on moisture-slicked roads and operating at a speed that permits stopping within visible distance during foggy conditions.
Estimated Time:45s
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Topics

Driving in Fog

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