Examkin

Question

Difficulty: MediumSpeed and Road Conditions

A commercial truck is traveling at 55 mph55\text{ mph} on an asphalt highway when a heavy rain shower causes water to accumulate in the tire ruts. What speed adjustment and vehicle control procedure should the driver follow to maintain traction and prevent hydroplaning?

  1. A
    Maintain the current speed of 55 mph55\text{ mph} while engaging the engine retarder at full capacity to keep the drive wheels firmly planted on the wet surface.
  2. Reduce road speed by about one-third to approximately 35 mph35\text{ mph} to 37 mph37\text{ mph}, and release the accelerator smoothly without hard braking if tires begin to hydroplane.Answer
  3. C
    Maintain highway speed until hydroplaning occurs, then apply forceful service brake pressure while turning the steering wheel to cut through standing water.
  4. D
    Reduce road speed by only 5 mph5\text{ mph} because heavy vehicle weight compensates for slippery pavement by pressing tires through pooled water to maintain normal stopping distance.

Answer

Reduce road speed by about one-third to approximately 35 mph35\text{ mph} to 37 mph37\text{ mph}, and release the accelerator smoothly without hard braking if tires begin to hydroplane.
According to official commercial driving standards, drivers must reduce their speed by approximately one-third on wet pavement (e.g., from 55 mph55\text{ mph} to about 35 mph35\text{ mph}–37 mph37\text{ mph}). If water accumulation leads to hydroplaning, the driver must smoothly ease off the accelerator and avoid hard braking or erratic steering to allow the tires to regain traction.

Step-by-Step Solution

1
Identify the prevailing road surface condition and required CDL speed reduction rule.
The road is wet with standing water, requiring a speed reduction of about one-third from the dry-road speed of 55 mph55\text{ mph}, bringing the vehicle to roughly 35 mph35\text{ mph} to 37 mph37\text{ mph}.
Water on the pavement reduces tire traction, and reducing speed by one-third counteracts the increased risk of skidding and hydroplaning.
2
Determine the correct driver response for managing traction and potential hydroplaning.
Do not use engine retarders on wet surfaces, avoid sudden steering maneuvers, and release the throttle without slamming on the brakes if the tires lose contact with the road.
Hard braking or retarder use on slick surfaces can lock the drive wheels and provoke a jackknife or uncontrolled skid.

Key Concept

Speed reduction on wet roads and hydroplaning control
Estimated Time:1m 0s
Rate this question

Topics

Speed and Road Conditions

More questions from this topic