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Difficulty: HardSeparation Distances and the Two-Second Rule

A motorist is driving on a dual carriageway behind another vehicle. Under dry weather conditions, the motorist maintains the minimum safe separation gap of 2 seconds as recommended by The Highway Code. When heavy rain begins, the motorist correctly doubles their following time gap to adjust for wet road conditions. As the journey continues into sub-zero temperatures, the road surface becomes covered in ice, requiring a following distance of up to 10 times the standard dry-weather gap. By how many seconds must the motorist increase their time separation gap when transitioning from wet road conditions to icy road conditions?

Answer: 16 seconds

Answer

16 seconds
Under The Highway Code, the baseline separation gap in dry conditions is 2 seconds. On wet roads, this gap is doubled to 4 seconds. On icy roads, stopping distances can increase up to 10 times the dry baseline, requiring a 20-second gap. The increase needed when moving from wet conditions (4 seconds) to icy conditions (20 seconds) is 20 - 4 = 16 seconds.

Step-by-Step Solution

1
Determine the baseline minimum following distance in dry conditions according to The Highway Code.
2 seconds
The two-second rule specifies a minimum 2-second time gap between vehicles on dry roads.
2
Calculate the safe time gap required in wet weather.
4 seconds
In wet conditions, stopping distances double, so the time gap must be doubled (2 seconds × 2 = 4 seconds).
3
Calculate the safe time gap required in icy conditions.
20 seconds
On icy roads, stopping distances can increase up to 10 times the normal dry distance, requiring a gap of 20 seconds (2 seconds × 10 = 20 seconds).
4
Calculate the additional time gap needed when transitioning from wet to icy conditions.
16 seconds
Subtracting the wet weather gap from the icy road gap gives the required increase (20 seconds - 4 seconds = 16 seconds).

Key Concept

Application of weather-dependent time gap multipliers based on The Highway Code's two-second separation rule.
Estimated Time:1m 30s
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Topics

Separation Distances and the Two-Second Rule

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