Theory Mastery

3-second rule: greater following distance in rain, snow, fog and heavy loads

What the exam asks here: 'Double your distance' is a rule of thumb you sometimes hear for bad weather.

14 minutes · 7 sections · 8 questions

The trap

Many learners think: In bad weather you double your following distance: from 2 to 4 seconds.

The rule is: 'keep a greater following distance (3 seconds) in difficult conditions.' From 2 to 3 seconds is 1.5x as much, not a doubling to 4

Challenge

'Double your distance' is a rule of thumb you sometimes hear for bad weather. That sounds logical, but the book names a different number: 3 seconds, not 4. The difference between '1.5x as much' and 'double' seems small, but on the exam that exact difference is what gets tested.

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The model

In rain, snow, fog, a heavily loaded vehicle, or a trailer/caravan: keep 3 seconds of distance (Book p.124), not the usual 2. That is 1.5x as much — not a doubling.

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Core

The book names five situations in which you extend the ordinary 2-second rule to 3 seconds: rain, snow, fog, a heavily loaded vehicle, and a trailer or caravan (Book p.124). In each of these cases your grip is lower or your braking distance longer than normal — the extra second compensates for that. Three seconds is 1.5 times as much as two, not a doubling to four. Anyone who takes 'double your distance' literally keeps too much distance and can end up being cut off or overtaken awkwardly on a busy road. The cause of many rear-end collisions on motorways is exactly this: too tight a following distance, combined with distraction or fatigue (Book p.124). The 3-second rule in difficult conditions is the direct countermeasure.

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Why it matters

On the A20 near Moordrecht, where fog often rolls in over the Groene Hart and traffic drives close together, 3 seconds is exactly enough to compensate for the longer braking distance on wet or slippery road surface — without leaving so much room that others squeeze in. Too little margin costs you reaction time; too much margin costs you the traffic flow.

Read this section on its own page: Why it matters: 3-second rule: greater following distance in rain, snow, fog and heavy loads

Active recall

Near Waddinxveen on the A20 dense fog descends. You are not towing a trailer and your car is not heavily loaded. What applies to your following distance?

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Teach back

Explain: in which five situations does the 3-second rule apply, and why is 'double your distance' an incorrect description?

Read this section on its own page: Teach back: 3-second rule: greater following distance in rain, snow, fog and heavy loads

Memory hook

Rain · snow · fog · heavy load · trailer = 3 sec., not 4. 1.5x the normal rule — not a doubling.

Read this section on its own page: Memory hook: 3-second rule: greater following distance in rain, snow, fog and heavy loads

Source: RVV 1990 art. 19 · checked 2026-10-22

The picture

Five triggers for the 3-second rule — each sufficient on its ownNormal conditionsDifficult conditions (Book p.124)Minimum following distance2 seconds3 secondsTriggersnone — standard road and vehiclerain · snow · fog · heavy load · trailer/caravan (each sufficient alone)Ratio to 2 sec.n/a1.5x — not a doubling to 4 sec.
What to look at: Normal: 2 seconds. Rain/snow/fog/heavy load/trailer: 3 seconds — 1.5x, not a doubling to 4.

Signs and law

Test yourself

On the A20 near Moordrecht it is raining hard and you are towing a fully loaded trailer. Normally you keep 2 seconds of distance. What changes now?

Show the answer

In rain, snow, fog, a heavily loaded vehicle, or a trailer/caravan: keep 3 seconds of distance (Book p.124), not the usual 2. That is 1.5x as much — not a doubling.

Exam questions on this topic

Near Bodegraven you are driving without a trailer and without a heavy load, but it is snowing lightly. What following distance do you keep?

  1. 3 seconds, because snow on its own is reason enough
  2. 2 seconds, because 3 is only for a trailer or a heavy load
  3. 4 seconds, because in snow you double the normal distance
Show the answer

Correct answer: 3 seconds, because snow on its own is reason enough

False — you think only load counts. Rain, snow and fog are each on their own a reason for 3 seconds, even without a trailer or heavy load.

Why learners get this wrong: The 3-second rule only applies with a heavily loaded vehicle or a trailer/caravan, not with rain, snow or fog.

Open this question

Near Boskoop you explain to a passenger: 'In rain you double your following distance: from 2 to 4 seconds.'

  1. True
  2. False
Show the answer

Correct answer: False

Why learners get this wrong: In bad weather you double your following distance: from 2 to 4 seconds.

Open this question

On the A20 near Nieuwerkerk aan den IJssel it starts to rain hard. You are driving an empty car without a trailer behind a van. Which following distance is the guideline here?

  1. About 4 seconds: in rain you double the usual 2 seconds
  2. About 3 seconds: the rain alone is already a reason for more distance
  3. About 2 seconds: 3 seconds applies only with a load or a caravan
Show the answer

Correct answer: About 3 seconds: the rain alone is already a reason for more distance

False — you think only a load counts. Rain, snow and fog are each on their own a reason for 3 seconds, just like a heavily loaded vehicle or a trailer or caravan

Why learners get this wrong: In bad weather you double your following distance: from 2 to 4 seconds.

Open this question

Near Reeuwijk it starts to snow. How many seconds of minimum following distance do you keep per the book?

Show the answer

Correct answer: 3 sec

Correct: 3.0 sec (±0.5).

Open this question

Near Gouderak you are towing a fully loaded trailer in clear, dry weather. What following distance do you keep?

  1. 3 seconds — the trailer alone is already sufficient reason, regardless of the weather
  2. 4 seconds — double the normal rule because the weight increases
Show the answer

Correct answer: 3 seconds — the trailer alone is already sufficient reason, regardless of the weather

Why learners get this wrong: In bad weather you double your following distance: from 2 to 4 seconds.

Open this question

Near Zevenhuizen an instructor explains: 'Most rear-end collisions on motorways happen because of following too closely, combined with distraction or fatigue — not because of broken brakes.'

  1. True
  2. False
Show the answer

Correct answer: True

Why learners get this wrong: Rear-end collisions on motorways are mainly caused by technical vehicle defects, not by driver behaviour.

Open this question

Rear-end collisions on motorways are mainly caused by technical vehicle defects, not by driver behaviour.

  1. False
  2. True
Show the answer

Correct answer: False

'too tight a following distance (combined with distraction or fatigue) is THE cause of the large number of rear-end collisions on motorways.' The book points to driving behaviour, not technology

Why learners get this wrong: Rear-end collisions on motorways are mainly caused by technical vehicle defects, not by driver behaviour.

Open this question

Near Waddinxveen on the A20 dense fog descends. You are not towing a trailer and your car is not heavily loaded. What applies to your following distance?

  1. 3 seconds — fog alone is already reason enough for the greater distance
  2. 4 seconds — double the normal 2-second rule
  3. Just 2 seconds — the 3-second rule only applies with a trailer or heavy load
Show the answer

Correct answer: 3 seconds — fog alone is already reason enough for the greater distance

The book names 3 seconds in fog, not 4 — that is 1.5x, not a doubling

Why learners get this wrong: In bad weather you double your following distance: from 2 to 4 seconds.

Open this question

Frequently asked questions

‘In bad weather you double your following distance: from 2 to 4 seconds’ – is that true?

No. 'keep a greater following distance (3 seconds) in difficult conditions.' From 2 to 3 seconds is 1.5x as much, not a doubling to 4

‘The 3-second rule only applies with a heavily loaded vehicle or a trailer/caravan, not with rain, snow or fog’ – is that true?

No. The text names rain, snow and fog as separate, standalone reasons for 3 seconds, independent of load or trailer — each of the five situations is sufficient on its own

‘Rear-end collisions on motorways are mainly caused by technical vehicle defects, not by driver behaviour’ – is that true?

No. 'too tight a following distance (combined with distraction or fatigue) is THE cause of the large number of rear-end collisions on motorways.' The book points to driving behaviour, not technology

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