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Risk perception

Stopping distances in Ireland: the rule and the questions

Part of risk perception. Read the rules, then test yourself.
Practise: Stopping distances

Stopping distances in Ireland is one of the rules the driver theory test asks about: the car test sets 40 questions in 45 minutes and 35 correct answers pass. This lesson gives the rule, an example from the road and questions tagged to it. Source: Citizens Information, page edited 6 May 2026, checked on 15 September 2026.

By the Irish Mock Test teamFacts checked 15 September 2026How we check facts

The legal rule is a sight line, not a number

Article 7 ties your speed to what you can see to be clear ahead, so it works in fog, at night and behind a hedge on a narrow country lane. No instrument read here puts a figure on it.

Source: Irish Statute Book, Road Traffic (Traffic and Parking) Regulations 1997, art. 7, checked on 2026-09-15

No Irish law sets a stopping distance figure. The legal duty is article 7 of the Traffic and Parking Regulations 1997: drive so that you can stop within the distance you can see to be clear. Figures such as 102 metres at 120 km/h are guidance in the RSA Rules of the Road, Revision No. 9.

The rules

  1. The legal rule is a sight line, not a number

    Article 7 ties your speed to what you can see to be clear ahead, so it works in fog, at night and behind a hedge on a narrow country lane. No instrument read here puts a figure on it.

    Road Traffic (Traffic and Parking) Regulations 1997, art. 7

  2. Total stopping distance is reaction distance plus braking distance

    Reaction distance, often called thinking distance, is the ground covered before the brakes take effect. Braking distance is what follows. Only the sum is the total minimum stopping distance, and that is what a question usually wants.

    Rules of the Road, Revision No. 9 (RSA guidance, not law)

  3. The dry figures climb much faster than the speed does

    Doubling your speed does not double the distance. In the RSA dry guidance 30 km/h needs 12 metres in total, 60 km/h needs 33 metres and 120 km/h needs 102 metres.

    Rules of the Road, Revision No. 9, dry conditions figures (RSA guidance)

  4. Wet roads push the braking half a long way out

    RSA wet guidance gives braking distance alone as at least 26 metres at 50 km/h and at least 101 metres at 100 km/h. Those are braking figures, before any reaction distance is added.

    Rules of the Road, Revision No. 9, wet conditions figures (RSA guidance)

  5. Two seconds dry, four wet, far more on ice

    The RSA advises a gap of at least two seconds in dry conditions, doubled in the wet, and four or five times that in snow, fog or ice. Timing it against a fixed point works at any speed. No instrument sets a following distance.

    Rules of the Road, Revision No. 9, the two-second rule (RSA guidance)

  6. Poor visibility brings a lighting duty with it

    Where daylight or weather cuts visibility, side and rear lamps must be lit, and headlamps too where they are needed to drive safely. On dipped beam the distance you can see to be clear is short.

    Road Traffic (Lighting of Vehicles) Regulations 1963, art. 20(1)(b), (2)

  7. Heavy vehicles are held to lower limits

    A goods vehicle over 3,500 kg takes 80 km/h on ordinary roads and 90 km/h on motorways. At 80 km/h the RSA dry total is 52 metres, 16 reaction and 36 braking, so the space ahead of a truck is not a courtesy.

    Road Traffic (Ordinary Speed Limits) Regulations 2008, reg. 4(a), as substituted by S.I. No. 255 of 2022

The RSA dry figures, restated

Reaction distance, then braking distance, then the total. These are guidance figures, so a question about what the law requires has a different answer from one about what the RSA advises.

  • 30 km/h: 6 plus 6, total 12 metres.
  • 40 km/h: 8 plus 10, total 18 metres.
  • 50 km/h: 10 plus 15, total 25 metres.
  • 60 km/h: 12 plus 21, total 33 metres.
  • 80 km/h: 16 plus 36, total 52 metres.
  • 100 km/h: 20 plus 50, total 70 metres.
  • 120 km/h: 24 plus 78, total 102 metres.

What the wet guidance covers, and what we could not read

The wet guidance gives two anchor points we could read: braking of at least 26 metres at 50 km/h and at least 101 metres at 100 km/h. The other speed labels there are drawn as images rather than text, so we publish no figures for them and do not estimate them.

On the road

The same 100 km/h, first dry and then wet

  1. Dry, at 100 km/h, the RSA guidance gives 20 metres of reaction and 50 metres of braking, so 70 metres in total.

  2. Rain starts. Wet guidance puts braking alone at 100 km/h at a minimum of 101 metres.

  3. Wet braking on its own is therefore longer than the whole dry stopping distance at that speed, with reaction distance still to add.

  4. Your gap changes to match: two seconds dry becomes at least four seconds wet, timed against a sign or bridge.

  5. Article 7 finishes the job. If spray cuts what you can see to be clear, your lawful speed drops below the 100 km/h road limit.

Where learners go wrong

  • Giving the braking distance when the question asks for the stopping distance. At 120 km/h braking is 78 metres and the total is 102 metres.

  • Treating the RSA figures as a legal standard. They are guidance; the enforceable rule is article 7.

  • Adding a small margin for rain. The guidance doubles the two-second gap in the wet and asks four or five times it in snow, fog or ice.

  • Assuming the dry figures describe a night drive. On dipped headlights it is the distance you can see to be clear that limits you.

  • Believing Irish law sets a minimum motorway speed. None was found. The only floor is that a vehicle must be able to hold 50 km/h on the level.

Sources

Source: rsa.ie, Rules of the Road, Revision No. 9 (RSA), stopping and following distance pages, checked on 2026-09-15

Source: irishstatutebook.ie, Road Traffic (Traffic and Parking) Regulations 1997, art. 7, checked on 2026-09-15

Source: irishstatutebook.ie, Road Traffic (Lighting of Vehicles) Regulations 1963, art. 20, checked on 2026-09-15

Source: irishstatutebook.ie, Roads Regulations 1994, art. 7(2) (vehicles allowed on a motorway), checked on 2026-09-15