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Question

Difficulty: EasyMountain Driving and Steep Downgrades

While descending a 5%5\% mountain downgrade on dry pavement with a 62000 lb62{}000\text{ lb} combination vehicle, a commercial driver experiences severe brake fade and cannot control the vehicle's speed. As the vehicle approaches a designated runaway truck escape ramp, what is the correct action for the driver to take?

  1. A
    Bypass the ramp and attempt to downshift into the lowest possible gear to regain engine braking.
  2. Steer directly onto the escape ramp without hesitation to bring the runaway vehicle to a stop.Answer
  3. C
    Apply continuous light pedal pressure while riding the paved shoulder to look for a level turnaround.
  4. D
    Activate the driveline retarder at full power while weaving across lanes to scrub off speed before entering the ramp.

Answer

Steer directly onto the escape ramp without hesitation to bring the runaway vehicle to a stop.
Steering directly onto the escape ramp without hesitation is the only correct emergency procedure when a driver experiences brake failure on a steep downgrade. Escape ramps use loose gravel, sand, or uphill slopes to safely dissipate vehicle kinetic energy. Drivers should never delay or hesitate, as waiting to see if control can be regained frequently results in catastrophic collisions.

Step-by-Step Solution

1
Recognize the onset of brake fade and runaway speed on a steep downgrade.
Identifies that the service brakes are overheated and no longer capable of slowing the vehicle.
Severe brake fade means friction surfaces have expanded away from drum linings, rendering foundation brakes ineffective.
2
Locate designated runaway truck escape infrastructure.
Spots the runaway truck escape ramp positioned along the downgrade.
Escape ramps provide engineered sand, pea gravel, or ascending grades specifically designed to absorb the kinetic energy of a runaway heavy vehicle.
3
Enter the escape ramp immediately without hesitation or delay.
Safely brings the commercial motor vehicle to a controlled halt without catastrophic collision.
Commercial driving safety regulations dictate that drivers must use an escape ramp immediately upon losing brake control rather than waiting or seeking alternative options.

Key Concept

Immediate Use of Runaway Truck Escape Ramps
Estimated Time:45s
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Topics

Mountain Driving and Steep Downgrades

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