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Question

Difficulty: MediumSpeed and Road Conditions

Adverse weather and changing surface conditions drastically reduce tire traction, requiring commercial drivers to adopt specific speed reductions and vehicle control measures. Match each roadway condition to its corresponding CDL speed regulation and vehicle control action.

  • Wet pavement following rainLower travel speed by approximately 1/31/3 to sustain traction and prevent hydroplaning
  • Packed snow covering the travel lanesCut travel speed by 1/21/2 or more and disable auxiliary engine braking systems
  • Sheet ice or freezing rain on the roadDecelerate to an absolute crawl and park in a safe location until conditions improve
  • Entering a sharp highway curveComplete all braking prior to the curvature so the vehicle rolls smoothly through the bend

Answer

Wet pavement matches with lowering speed by about 1/3; packed snow matches with cutting speed by 1/2 or more and turning off retarders; sheet ice matches with slowing to a crawl and seeking safe parking; curve approach matches with braking completely before entering the curvature.
Each roadway condition dictates a specific, federally recognized speed adjustment and vehicle management strategy: wet roads necessitate a one-third speed reduction; packed snow requires cutting speed by at least half while disabling engine retarders; ice mandates slowing to a crawl; and curves require slowing down completely before entering.

Step-by-Step Solution

1
Identify the traction reduction factor for wet pavement and match with standard CDL proportion.
Wet pavement reduces tire contact; the standard required reduction is approximately 1/31/3 of the posted dry speed.
Prevents dynamic hydroplaning and extends stopping distance safely.
2
Determine the required operating actions for packed snow and ice.
Packed snow requires reducing speed by 1/21/2 or more with retarders disabled; sheet ice demands reducing to a crawl and halting operations as soon as possible.
Packed snow severely degrades friction, while ice provides almost zero coefficient of friction, creating extreme skid hazards.
3
Identify proper curve management speed protocol.
Deceleration must occur before entering the curve rather than braking within the turn.
Braking during a turn combines lateral cornering forces with longitudinal braking forces, exceeding available tire grip.

Key Concept

CDL Speed Adjustment Proportions and Dynamic Vehicle Control under Adverse Road Conditions
Estimated Time:1m 0s
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Topics

Speed and Road Conditions

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