Rule
How to use it
When the car ahead passes a fixed point (a sign, a road marking, a kerbstone), count 'one-thousand, two-thousand, three-thousand'. If you reach the point before you finish counting, you're too close.
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Lesson4 min
The 3-second rule
A practical way to keep safe distance — without counting metres.
You will learn, among other things:
Example
Why three seconds?
Three seconds is the time you need to see a hazard, react, and start braking without hitting the car ahead if it brakes hard. At 90 km/h, three seconds is about 75 m. That is not the same thing as your stopping distance. At 90 km/h on dry asphalt the stopping distance is about 59 m, reaction 27 m plus braking 32 m. The three-second gap is deliberately larger, because the car ahead is braking too, and because three seconds is something you can count while metres are something you can only guess at.
Exam trap
Double it in bad conditions
• Rain or wet road → at least 4 seconds • Snow or ice → 8–10 seconds • Fog or reduced visibility → your sight distance is what matters. You must always be able to stop within it, not a fixed second count • Behind a heavy truck (blocks your view ahead) → increase the gap further The rule is a minimum, not a target.