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Difficulty: Very hardWinter Driving

An operator is driving a 70-foot commercial combination vehicle at 45 mph on an unlit rural highway. The ambient temperature has recently dropped to 31°F (-1°C) and freezing rain has begun to fall. The operator notices that the steering feels abnormally light and the vehicle ahead is no longer kicking up water spray from its tires. Based on commercial driving safety protocols, which combination of evaluations and immediate actions is required?

  1. Identify the sudden lack of tire spray and light steering as indicators of black ice; ensure the engine retarder is completely deactivated, gently let off the accelerator, and recognize that the current speed is unsafe for the extreme loss of traction.Answer
  2. B
    Conclude the road is slick and immediately engage the engine retarder on its lowest setting to carefully manage downhill momentum without risking a service brake lockup.
  3. C
    Calculate a standard safe following distance of 8 seconds (7 seconds for vehicle length plus 1 second for exceeding 40 mph) and maintain this exact interval using cruise control.
  4. D
    Assume the lack of spray indicates hydroplaning rather than ice; maintain speed relying on the steer tires having a legal minimum tread depth of 2/32 inch to displace the accumulating water.

Answer

Identify the sudden lack of tire spray and light steering as indicators of black ice; ensure the engine retarder is completely deactivated, gently let off the accelerator, and recognize that the current speed is unsafe for the extreme loss of traction.
The scenario perfectly describes the onset of black ice (freezing temperatures, lack of tire spray, and light steering feel). Under these extreme low-traction conditions, the CDL manual strictly mandates deactivating all engine retarders to prevent drive-wheel skids, decelerating smoothly without sudden braking, and recognizing that standard speeds and following distances are no longer safe.

Step-by-Step Solution

1
Analyze the environmental and tactile cues presented in the scenario.
Temperature near freezing, freezing rain, lack of tire spray from other vehicles, and light steering are definitive signs of black ice formation.
Recognizing hazards early is a fundamental requirement of space and speed management in winter conditions.
2
Determine the appropriate mechanical response for the engine retarder.
The engine retarder must be immediately and completely deactivated.
Engine retarders apply braking force only to the drive wheels. On slick surfaces like black ice, this uneven braking force will break traction and cause an immediate drive-wheel skid.
3
Determine the appropriate vehicle control response.
The driver must gently release the accelerator and avoid applying the service brakes or making sudden steering movements.
Any abrupt change in speed or direction on black ice will result in a complete loss of vehicle control.

Key Concept

Identifying hidden winter hazards (black ice) and executing the mandated mechanical and handling adjustments to prevent traction loss.
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Topics

Winter Driving

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