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Difficulty: MediumAdjusting Margins in Fog and High Winds

You are driving along an unlit dual carriageway at night when a thick bank of fog suddenly reduces your visibility to approximately 50 metres. What should you do to maintain safe driving margins and vehicle visibility?

  1. A
    Maintain your usual two-second following gap and closely track the rear lights of the vehicle ahead
  2. Switch on dipped headlights and fog lights, reduce your speed, and significantly increase your following distanceAnswer
  3. C
    Switch on main-beam headlights and maintain the posted speed limit to keep traffic flowing smoothly
  4. D
    Apply the standard four-second following rule used for wet roads and travel using only your sidelights

Answer

Turn on dipped headlights and fog lights, reduce speed, and significantly increase the separation distance behind the vehicle ahead.
When visibility is reduced to 100 metres or less, the Highway Code requires the use of dipped headlights and fog lights. Because visibility is limited to 50 metres, speed must be reduced substantially and following distance must be greatly increased so that the vehicle can comfortably stop within the visible distance ahead.

Step-by-Step Solution

1
Assess the forward visibility against Highway Code criteria.
Visibility of 50 metres is well below the statutory 100-metre threshold for using front and rear fog lights (Rule 226).
Correct lighting ensures your vehicle is conspicuous to other road users without causing excessive glare.
2
Adjust vehicle lighting correctly.
Dipped headlights and fog lights are activated, avoiding main beam which reflects light back into the driver's eyes.
Dipped beams illuminate the road surface immediately ahead rather than scattering against fog particles.
3
Recalculate speed and safety margins.
Vehicle speed is reduced and following distance is extended beyond normal margins.
Drivers must always be able to pull up smoothly within the distance they can clearly see to be clear.

Key Concept

Adjusting safety margins, speed, and lamp usage in dense fog conditions
Estimated Time:45s
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Topics

Adjusting Margins in Fog and High Winds

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