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Question

Difficulty: MediumMountain Driving and Steep Grades

While driving on a mountain highway, you approach a yellow, diamond-shaped warning sign depicting a truck descending a slope with the inscription '6% GRADE - NEXT 5 MILES'. What does this sign signify, and what is the safest procedure to prepare for the descent?

  1. It warns of a steep downhill slope ahead; drivers should reduce speed and shift into a lower gear before starting the descent to assist with speed control.Answer
  2. B
    It is a mandatory regulatory order requiring all vehicles to reduce their speed to exactly 6 mph for the next five miles.
  3. C
    It indicates that the lane is restricted exclusively to commercial vehicles for the next five miles.
  4. D
    It advises drivers to maintain maximum highway speed and shift into neutral to conserve fuel while coasting down the slope.

Answer

The sign warns of a steep downhill grade ahead; drivers must slow down and select a lower gear before beginning the descent to maintain control using engine braking.
Yellow diamond signs advise drivers of upcoming hazardous road conditions. When facing a steep grade, reducing speed and shifting into a lower gear prior to beginning the descent utilizes engine braking, minimizing reliance on foot brakes and preventing thermal brake fade.

Step-by-Step Solution

1
Identify the sign shape and color
Recognize that a yellow diamond sign is a warning sign alerting drivers to upcoming physical road hazards.
Understanding sign geometry and color coding allows drivers to distinguish advisory warnings from mandatory regulatory mandates.
2
Interpret the specific message and percentage
Understand that '6% GRADE' indicates a steep downhill slope over a five-mile stretch.
Steep descents increase momentum and kinetic energy, placing extra stress on the vehicle's braking system.
3
Determine the proper preventative driving action
Slow down and shift to a lower gear before descending.
Pre-positioning the transmission into a lower gear enables engine braking, protecting the service brakes from overheating and failing.

Key Concept

Warning Sign Interpretation and Mountain Grade Vehicle Control
Estimated Time:1m 0s
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Topics

Mountain Driving and Steep Grades

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