A driver travelling on a dual carriageway at 50\text{ mph} encounters severe winter condit… — UK Driving Theory Test

A driver travelling on a dual carriageway at $50\text{ mph}$ encounters severe winter conditions where the road surface is covered with packed snow and ice. In standard dry conditions, the average total stopping distance is $53\text{ metres}$ at $50\text{ mph}$ and $12\text{ metres}$ at $20\text{ mph}$ . According to The Highway Code, stopping distances on ice can be up to $10\text{ times}$ greater than in dry conditions. If the driver slows down from $50\text{ mph}$ to $20\text{ mph}$ , by how many metres is their maximum potential stopping distance on ice reduced?

Answer: 410 metres

Answer

The maximum potential stopping distance on ice is reduced by

410\text{ metres}

According to The Highway Code (Rule 230), stopping distances in icy or snowy conditions can be up to ten times greater than on dry tarmac. At

50\text{ mph}

, a dry stopping distance of

53\text{ metres}

becomes up to

530\text{ metres}

on ice. At

20\text{ mph}

, a dry stopping distance of

12\text{ metres}

becomes up to

120\text{ metres}

on ice. Slowing down from

50\text{ mph}

20\text{ mph}

reduces the stopping distance by

530\text{ m} - 120\text{ m} = 410\text{ metres}

, drastically lowering collision risk.

Step-by-Step Solution

Determine the stopping distance on ice at

50\text{ mph}

530 metres

The Highway Code states that stopping distances on ice and snow can increase up to 10 times the normal dry stopping distance (

53\text{ m} \times 10 = 530\text{ m}

Determine the stopping distance on ice at the reduced speed of

20\text{ mph}

120 metres

Applying the 10-times multiplier to the baseline dry stopping distance of

12\text{ metres}

gives

12\text{ m} \times 10 = 120\text{ m}

Calculate the difference between the two stopping distances on ice

410 metres

Subtracting the stopping distance at

20\text{ mph}

from the stopping distance at

50\text{ mph}

yields the total reduction in safety margin:

530\text{ m} - 120\text{ m} = 410\text{ m}

Key Concept

Highway Code stopping distance multipliers and safety margin adjustments on ice and snow

Estimated Time:1m 30s

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