Theory Mastery

Calculating overtaking distance: the 60-formula and the blind spot

What the exam asks here: Most students estimate this distance by feel, or even think a smaller speed difference makes the manoeuvre shorter.

14 minutes · 7 sections · 11 questions

The trap

Many learners think: The smaller the speed difference with the vehicle ahead, the shorter the overtaking distance you need.

The rule is: At 80 km/h and a leader at 25 km/h the overtaking distance is 87 metres; at 80 km/h and a leader at 60 km/h (a smaller difference) the overtaking distance is 240 metres

Challenge

Most students estimate this distance by feel, or even think a smaller speed difference makes the manoeuvre shorter. The CBR exam designer counts on that: the formula gives exactly the opposite answer to what intuition says, and whoever does not know the formula also misses the blind-spot check that always precedes it.

Read this section on its own page: Challenge: Calculating overtaking distance: the 60-formula and the blind spot

The model

The formula: 60 x your own speed : the speed difference. At 80 km/h against a lead vehicle doing 25 km/h: 60 x 80 : 55 = 87 metres (Book p.143). With a SMALLER difference — 80 against 60 km/h — the distance becomes 240 metres instead. Right before overtaking: interior mirror, left exterior mirror, then over the left shoulder for the blind spot.

Read this section on its own page: The model: Calculating overtaking distance: the 60-formula and the blind spot

Core

The overtaking-distance formula reads (Book p.143): 60 x your own speed, divided by the speed difference between you and the vehicle ahead. If you drive 80 km/h and the vehicle ahead drives 25 km/h, the difference is 55 km/h: 60 x 80 : 55 = 87 metres. If the vehicle ahead instead drives 60 km/h — a SMALLER difference of 20 km/h — the result becomes 60 x 80 : 20 = 240 metres. The smaller the difference, the longer you need to overtake, not shorter. Before you actually start overtaking, you check the blind spot in three fixed steps (Book p.143): first the interior mirror, then the left exterior mirror, and finally over your left shoulder. Only that last step reveals a vehicle invisible in any mirror. Two distance rules belong to the overtaking manoeuvre itself (Book p.145): when overtaking pedestrians and cyclists, keep a lateral distance of at least 1.5 metres, and before overtaking keep sufficient distance to the vehicle ahead (the 2-second rule), so it can see you coming clearly. On the motorway overtaking is usually safely possible (Book p.147), but limits still apply there too: the manoeuvre may not take longer than necessary, and you may not exceed the maximum speed — 'usually safe' is not a free pass for unlimited-duration or unlimited-speed overtaking.

Read this section on its own page: Core: Calculating overtaking distance: the 60-formula and the blind spot

Why it matters

Underestimate the overtaking distance at a small speed difference, and you are still halfway across the left lane when oncoming or following traffic appears — exactly the scenario that leads to head-on collisions on the narrow provincial roads around Baarland. And whoever skips the last step of the blind-spot check misses a motorcyclist or car that no mirror shows, even though the manoeuvre feels perfectly safe at that moment.

Read this section on its own page: Why it matters: Calculating overtaking distance: the 60-formula and the blind spot

Active recall

Near Ellewoutsdijk you are driving at 80 km/h behind a tractor doing 60 km/h and want to overtake after only briefly checking your left exterior mirror. Is that enough?

Read this section on its own page: Active recall: Calculating overtaking distance: the 60-formula and the blind spot

Teach back

Explain: how do you calculate the overtaking distance, why does that distance get LONGER with a smaller speed difference, and which three steps do you check before overtaking?

Read this section on its own page: Teach back: Calculating overtaking distance: the 60-formula and the blind spot

Memory hook

60 x own speed : difference. Smaller difference = longer distance. Before overtaking: interior mirror, exterior mirror, shoulder — and at least 1.5 m past cyclists/pedestrians.

Read this section on its own page: Memory hook: Calculating overtaking distance: the 60-formula and the blind spot

The picture

Overtaking distance: a smaller speed difference needs a longer distance80 km/h vs. 25 km/h lead vehicle (p.143)80 km/h vs. 60 km/h lead vehicle (p.143)Speed difference55 km/h (large difference)20 km/h (small difference)Calculation (60 x own speed : difference)60 x 80 : 55 = 87 m60 x 80 : 20 = 240 mRequired overtaking distance87 metres — shorter240 metres — almost 3x as long
What to look at: 80 vs 25 km/h = 87 m overtaking distance. 80 vs 60 km/h = 240 m. Smaller difference = longer distance. Blind spot: interior mirror, exterior mirror, shoulder.

Test yourself

On the provincial road near Nisse you are driving at 80 km/h behind an agricultural vehicle doing 25 km/h and want to overtake. How many metres of overtaking distance do you need at minimum?

Show the answer

The formula: 60 x your own speed : the speed difference. At 80 km/h against a lead vehicle doing 25 km/h: 60 x 80 : 55 = 87 metres (Book p.143). With a SMALLER difference — 80 against 60 km/h — the distance becomes 240 metres instead. Right before overtaking: interior mirror, left exterior mirror, then over the left shoulder for the blind spot.

Exam questions on this topic

About Calculating overtaking distance: the 60-formula and the blind spot: which statement is WRONG?

  1. Even on the motorway the manoeuvre may not take longer than necessary, and you may not exceed the maximum speed.
  2. At 80 km/h and a leader at 25 km/h the overtaking distance is 87 metres; at 80 km/h and a leader at 60 km/h (a smaller difference) the overtaking distance is 240 metres.
  3. The sequence is three steps: first the interior mirror, then the left exterior mirror, AND THEN over your left shoulder — only that last step covers the blind spot no mirror shows (trap: final check step skipped).
  4. The 1.5 metre lateral clearance when overtaking cyclists and pedestrians only applies at high speed, such as on a motorway.
Show the answer

Correct answer: The 1.5 metre lateral clearance when overtaking cyclists and pedestrians only applies at high speed, such as on a motorway.

The rule is stated generally: 'when overtaking pedestrians and cyclists, keep sufficient lateral distance (at least 1.5 metres)', with no restriction to motorways or high speed

Why learners get this wrong: On the motorway overtaking is always safe, so the manoeuvre may take as long as you like.

Open this question

About Calculating overtaking distance: the 60-formula and the blind spot: which statements are correct? (multiple answers possible)

  1. The rule is stated generally: 'when overtaking pedestrians and cyclists, keep sufficient lateral distance (at least 1.5 metres)', with no restriction to motorways or high speed.
  2. Before overtaking it is enough to check your interior mirror and left exterior mirror; checking over your shoulder is then no longer necessary.
  3. Before overtaking you first look over your left shoulder and only then in the mirrors.
  4. Right before overtaking, keep sufficient distance to the vehicle ahead (2-second rule), so it can see you coming clearly.
Show the answer

Correct answer: The rule is stated generally: 'when overtaking pedestrians and cyclists, keep sufficient lateral distance (at least 1.5 metres)', with no restriction to motorways or high speed.; Right before overtaking, keep sufficient distance to the vehicle ahead (2-second rule), so it can see you coming clearly.

The book's sequence starts with the interior mirror, not with the shoulder check

Why learners get this wrong: Before overtaking it is enough to check your interior mirror and left exterior mirror; checking over your shoulder is then no longer necessary.

Open this question

Near Ellewoutsdijk you are driving at 80 km/h behind a tractor doing 60 km/h and want to overtake after only briefly checking your left exterior mirror. Is that enough?

  1. Yes, the interior mirror and left exterior mirror together already cover everything
  2. No, you must also look over your left shoulder to cover the blind spot
Show the answer

Correct answer: No, you must also look over your left shoulder to cover the blind spot

Only the look over the left shoulder covers the blind spot that no mirror shows

Why learners get this wrong: Before overtaking it is enough to check your interior mirror and left exterior mirror; checking over your shoulder is then no longer necessary.

Open this question

About Calculating overtaking distance: the 60-formula and the blind spot: which statement is WRONG?

  1. The sequence is three steps: first the interior mirror, then the left exterior mirror, AND THEN over your left shoulder — only that last step covers the blind spot no mirror shows (trap: final check step skipped).
  2. The rule is stated generally: 'when overtaking pedestrians and cyclists, keep sufficient lateral distance (at least 1.5 metres)', with no restriction to motorways or high speed.
  3. On the motorway overtaking is always safe, so the manoeuvre may take as long as you like.
  4. At 80 km/h and a leader at 25 km/h the overtaking distance is 87 metres; at 80 km/h and a leader at 60 km/h (a smaller difference) the overtaking distance is 240 metres.
Show the answer

Correct answer: On the motorway overtaking is always safe, so the manoeuvre may take as long as you like.

Even on the motorway the manoeuvre may not take longer than necessary, and you may not exceed the maximum speed

Why learners get this wrong: Before overtaking it is enough to check your interior mirror and left exterior mirror; checking over your shoulder is then no longer necessary.

Open this question

Even on the motorway the manoeuvre may not take longer than necessary, and you may not exceed the maximum speed.

  1. False
  2. True
Show the answer

Correct answer: True

Even on the motorway the manoeuvre may not take longer than necessary, and you may not exceed the maximum speed

Why learners get this wrong: On the motorway overtaking is always safe, so the manoeuvre may take as long as you like.

Open this question

Near Hoedekenskerke you are driving at 80 km/h behind a lead vehicle at 25 km/h. How many metres of overtaking distance do you need according to the formula 60 x own speed : speed difference (in metres)?

Show the answer

Correct answer: 87 m

Correct: 87.0 m (±5.0).

Open this question

What is the correct sequence for checking the blind spot before overtaking (Book p.143)?

  1. Interior mirror, left exterior mirror, over the left shoulder
  2. Over the left shoulder, then the mirrors
  3. Interior mirror and left exterior mirror are enough, no shoulder check needed
Show the answer

Correct answer: Interior mirror, left exterior mirror, over the left shoulder

False — The book's sequence starts with the interior mirror, not with the shoulder check

Why learners get this wrong: Before overtaking you first look over your left shoulder and only then in the mirrors.

Open this question

Statement: the rule of a minimum 1.5 metre lateral distance when overtaking cyclists and pedestrians only applies at high speed, such as on the motorway.

  1. True
  2. False
Show the answer

Correct answer: False

Why learners get this wrong: The 1.5 metre lateral clearance when overtaking cyclists and pedestrians only applies at high speed, such as on a motorway.

Open this question

Near Sluiskil you are driving at 80 km/h behind a vehicle doing 25 km/h; overtaking it would have taken about 87 metres. Just before you start, the vehicle ahead speeds up to 60 km/h. You are still doing 80 km/h. How much overtaking distance do you need now?

  1. About 240 metres, much more than the earlier 87 metres
  2. About 40 metres, much less than the earlier 87 metres
  3. Still about 87 metres, because you yourself are still doing 80 km/h
Show the answer

Correct answer: About 240 metres, much more than the earlier 87 metres

False — You only look at your own speed. The overtaking distance depends on the speed difference with the vehicle ahead: 60 x your speed : difference, so now 60 x 80 : 20 = 240 metres

Why learners get this wrong: The smaller the speed difference with the vehicle ahead, the shorter the overtaking distance you need.

Open this question

Which statements about overtaking are correct? (multiple answers possible)

  1. Keep at least 1.5 metres of lateral distance when overtaking cyclists
  2. The 2-second rule to your lead vehicle is only relevant during normal driving, not right before overtaking
  3. On the motorway overtaking is always safe, so the manoeuvre may take as long as you like
  4. Even on the motorway the overtaking manoeuvre may not take longer than necessary
Show the answer

Correct answer: Keep at least 1.5 metres of lateral distance when overtaking cyclists; Even on the motorway the overtaking manoeuvre may not take longer than necessary

Why learners get this wrong: The 2-second rule is only about following distance during normal driving and has nothing to do with overtaking.

Open this question

All practice questions of this topic

Frequently asked questions

‘The smaller the speed difference with the vehicle ahead, the shorter the overtaking distance you need’ – is that true?

No. At 80 km/h and a leader at 25 km/h the overtaking distance is 87 metres; at 80 km/h and a leader at 60 km/h (a smaller difference) the overtaking distance is 240 metres

‘Before overtaking it is enough to check your interior mirror and left exterior mirror; checking over your shoulder is then no longer necessary’ – is that true?

No. The sequence is three steps: first the interior mirror, then the left exterior mirror, AND THEN over your left shoulder — only that last step covers the blind spot no mirror shows (trap: final check step skipped).

‘The 1.5 metre lateral clearance when overtaking cyclists and pedestrians only applies at high speed, such as on a motorway’ – is that true?

No. The rule is stated generally: 'when overtaking pedestrians and cyclists, keep sufficient lateral distance (at least 1.5 metres)', with no restriction to motorways or high speed

‘On the motorway overtaking is always safe, so the manoeuvre may take as long as you like’ – is that true?

No. Even on the motorway the manoeuvre may not take longer than necessary, and you may not exceed the maximum speed

‘The 2-second rule is only about following distance during normal driving and has nothing to do with overtaking’ – is that true?

No. Right before overtaking, keep sufficient distance to the vehicle ahead (2-second rule), so it can see you coming clearly

Related topics

Open in the app