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Difficulty: MediumMountain Driving and Steep Downgrades

While descending a 4-mile4\text{-mile}, 5%5\% mountain grade with a gross combination weight of 62,000 lbs62,000\text{ lbs}, you notice your brake pedal feels soft, stopping power is rapidly fading, and your road speed continues to climb past your designated safe speed. You observe a designated runaway vehicle escape ramp 500 yards500\text{ yards} ahead. Which of the following is the correct action to take?

  1. A
    Continue down the grade while applying continuous, heavy pressure to the service brakes to regain control before reaching the bottom.
  2. Steer into the runaway truck escape ramp immediately to bring the vehicle to a safe, controlled stop.Answer
  3. C
    Attempt to force the transmission into lowest gear across neutral while bypassing the ramp to preserve the vehicle from gravel bed damage.
  4. D
    Bypass the escape ramp and immediately engage the engine retarder at maximum setting to arrest the vehicle on the roadway.

Answer

Steer into the runaway truck escape ramp immediately to bring the vehicle to a safe, controlled stop.
When a commercial motor vehicle experiences brake fade and uncontrollable acceleration on a steep downgrade, the driver must steer into an escape ramp immediately. Escape ramps use loose gravel beds, sand, or steep upward grades to stop a runaway vehicle safely, preventing deadly crashes.

Step-by-Step Solution

1
Recognize the symptoms of mechanical brake fade
Identify that a soft pedal and accelerating speed on a downgrade mean the friction brakes have overheated and lost stopping effectiveness.
Continuing to rely on overheated service brakes will lead to complete loss of vehicle control.
2
Evaluate the immediate escape options
Identify the upcoming escape ramp as the designated emergency measure built specifically to arrest runaway commercial vehicles.
Escape ramps are engineered with soft gravel beds or uphill grades to safely stop out-of-control vehicles.
3
Execute the emergency escape maneuver without hesitation
Steer straight into the escape ramp immediately rather than trying risky maneuvers or worrying about vehicle recovery.
Any delay or attempt to bypass an escape ramp drastically increases the likelihood of a fatal rollover or high-speed collision.

Key Concept

Brake Fade and Runaway Truck Escape Ramp Procedures
Estimated Time:1m 0s
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Topics

Mountain Driving and Steep Downgrades

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