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Question

Difficulty: HardSkidding Causes and Prevention

You are about to descend a steep hill on a road covered in compacted snow and ice. Which driving action should you take to minimise the risk of skidding and maintain directional control?

  1. A
    Coast down the gradient in neutral while applying intermittent pressure to the handbrake
  2. B
    Remain in a high gear and pump the footbrake forcefully throughout the entire descent
  3. Select a low gear before starting the descent and avoid abrupt braking, allowing engine braking to regulate speedAnswer
  4. D
    Descend in top gear using light accelerator pressure to maintain forward momentum and clear the slope quickly

Answer

Selecting a low gear before beginning the descent and avoiding sudden braking, relying on engine braking to regulate speed smoothly.
On severe downhill gradients covered with ice or snow, pre-selecting a low gear before starting the descent allows engine compression to naturally govern the vehicle's speed. This minimizes reliance on the friction footbrake, preventing wheel lockup and preserving steering traction.

Step-by-Step Solution

1
Assess the severe risk of traction loss caused by the combination of a steep downward gradient and low-friction icy surface.
Identified that mechanical footbrake application creates an immediate risk of wheel lockup and skidding.
On compacted snow and ice, available tyre grip is extremely limited, so lateral steering and longitudinal braking forces must be minimised.
2
Select an appropriate lower gear before descending the slope.
The engine compression naturally resists wheel rotation without abruptly locking the drive wheels.
Pre-selecting a low gear ensures continuous, smooth deceleration via engine braking and keeps steering wheels turning freely.
3
Maintain a low, steady speed and avoid sudden steering or braking inputs.
The vehicle safely negotiates the gradient while retaining full steering authority.
Smooth, gentle control inputs keep the tyres within their friction circle threshold.

Key Concept

Using engine braking and low gear selection to prevent wheel lockup and skidding on steep, low-friction surfaces.
Estimated Time:1m 15s
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Topics

Skidding Causes and Prevention

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