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Question

Difficulty: EasySpeed and Road Conditions

While driving on a highway during a sudden downpour, a commercial driver notices water spraying from surrounding traffic and feels the steering wheel suddenly lose resistance, indicating the vehicle is beginning to hydroplane. What is the safest immediate action for the driver to take?

  1. A
    Engage the engine retarder to provide supplemental braking on the drive axle.
  2. Release the accelerator pedal and push in the clutch to allow the tires to regain traction.Answer
  3. C
    Apply continuous hard pressure to the foot brake to force tire contact with the pavement.
  4. D
    Maintain engine throttle and pump the service brakes rapidly to dry out the brake drums.

Answer

Release the accelerator pedal and push in the clutch to allow the tires to regain traction.
When a commercial vehicle hydroplanes, the tires lose physical contact with the pavement and ride atop water. The correct CDL procedure is to release the accelerator and push in the clutch. This removes drivetrain torque and allows the wheels to turn freely, slowing the vehicle down smoothly until the tires cut through the water film and regain grip.

Step-by-Step Solution

1
Recognize the signs of hydroplaning, such as loose steering feel and water spraying from adjacent tires.
Driver identifies that the tires are riding on a film of water rather than the pavement surface.
Immediate recognition is required before inappropriate control inputs cause a loss of directional stability.
2
Avoid applying service brakes or engaging engine retarders.
Wheels are protected from locking up during total traction loss.
Braking while hydroplaning causes immediate wheel lockup and skidding.
3
Release the accelerator and press the clutch pedal.
Drivetrain torque is removed, allowing tires to roll freely and re-establish contact with the road.
Free-rolling tires naturally displace the water film and restore steering and tracking control.

Key Concept

Hydroplaning Recovery and Traction Management on Wet Roadways
Estimated Time:45s
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Topics

Speed and Road Conditions

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