Patente Quiz B
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Lesson and quiz, category B licence

Safe following distance (Distanza di sicurezza)

On the exam this topic tests what the Codice requires on following distance, how total stopping distance is made up, and which conditions make it longer; this site has 22 true or false statements to practise on it.

The theory exam has 30 statements in 20 minutes and you pass with at most 3 mistakes. Source: Codice della Strada.

Skip to the quiz Study the rules

The real theory exam is in Italian, with French or German available on request. Lessons here keep the Italian terms in italics, and the quiz shows each statement in Italian with English help underneath. Switch to Italian only in the quiz to practise under exam conditions.

The rules

Question 1 of 1

Rule 1

The rule: being able to stop in time

You keep a distance from the vehicle ahead that guarantees in every case that you can stop in time and avoid a collision. The Codice sets no single number of metres. It does set two special minimums: 100 metres outside built up areas between vehicles that are banned from overtaking, and 20 metres from snowploughs or gritters at work.

Example

In a queue at 30 km/h in town the car ahead brakes hard. The gap you left is what prevents the shunt, even at low speed.

Legal reference: CdS art. 149, c. 1, 2, 3

Exam traps

  • «A fixed number of metres, the same at qualunque (any) speed»: false.
  • «Not responsible for the shunt»: a driver following too closely is responsible, because the gap exists for sudden braking.

Rule 2

Reaction, braking and stopping distance

Total stopping distance (spazio di arresto) has two parts. Reaction distance (spazio di reazione) is covered between seeing the hazard and pressing the brake, with an average reaction time of about one second. Braking distance (spazio di frenata) is covered from when the brakes act until the car stops, and it grows with the square of the speed.

Example

At 50 km/h you cover about 14 metres a second, at 100 km/h about 28. Double the speed and reaction distance doubles, while braking distance becomes about four times longer.

Stopping distance at 50 and 100 km/h 50 km/h about 28 m 100 km/h about 83 m reaction braking
Rough figures: 1 second reaction, dry road. At twice the speed, braking is about four times longer.

Exam traps

  • «Doubling the speed doubles braking distance»: false, it quadruples.
  • «Stopping distance is the same as braking distance»: false, it leaves out reaction distance.
  • «At low speed reaction distance is zero»: it shrinks but is never zero.

Rule 3

What makes stopping distance longer

Braking distance gets longer on wet roads, snow and ice, with worn tyres, poor brakes and more mass, such as a heavy load. Reaction time gets longer with tiredness, alcohol, some medicines and distraction. Engine power affects acceleration, not stopping.

Example

With the car loaded for a holiday and a wet road, you leave far more room than usual to the car ahead.

Legal reference: CdS art. 149, c. 1

Exam traps

  • «It depends soltanto (only) on engine power»: false.
  • «It can be reduced on a wet surface» or «in tunnels»: false in both cases.

Rule 4

Poor visibility and ABS

When a van or lorry blocks the view ahead, or visibility is poor, you increase the gap because you will react later. Sitting close behind someone narrows what you can see. ABS stops the wheels locking and keeps steering possible, but it does not let you shorten the gap; on gravel or fresh snow it can even lengthen braking.

Example

In fog all you can see is the tail lights of the car ahead. It is tempting to follow them closely, but the gap must grow.

Legal reference: CdS art. 149, c. 1

Exam traps

  • «It is best to close up and follow the tail lights»: false.
  • «ABS allows a shorter safe distance»: false.

Rule 5

What can go wrong

Three typical crashes explain why safe following distance changes with speed, load and visibility. First: on the A1 in a queue at 100 km/h the driver keeps fifteen metres from the car ahead, the gap that eye judgement calls reassuring. At that speed the car covers about 28 metres a second: reaction distance alone eats more than fifteen metres before the brakes even bite. A sudden braking ahead becomes a chain shunt. Art. 149 of the Codice della Strada asks for a gap that allows a timely stop, and at that speed it means far more. Second: in a tunnel near Genoa the driver closes in on the lorry ahead to see the road better. The lorry brakes for a queue. The blocked view hid the hazard, reaction time grew, the gap was too short. Sitting on the tail of a big vehicle does not help driving; it narrows the field of view and triples the shunt risk. Third: on a Po Valley main road in the rain, tyres worn to the 1.6 millimetre minimum. The driver keeps the same gap as on a dry road. A car ahead brakes for mud on the carriageway. A skid and a hit. Wet surface and worn tyres have stretched braking distance by more than fifty per cent. The rule of thumb is the same in all three cases. Reaction distance grows with speed, braking distance grows with the square of the speed, and total stopping distance also turns on load, tyres, rain and tiredness. A useful practical guide is the two second rule, to be raised to three or four in rain, in tunnels or with a heavy load. ABS never shortens the gap: it helps you steer, not stop sooner.

Legal reference: CdS art. 149

CdS: Codice della Strada (d.lgs. 285/1992). Reg.: its implementing regulation (d.P.R. 495/1992). c.: comma, the numbered paragraph of an article.

Full text of the Codice: www.aci.it/i-servizi/normative/codice-della-strada.html

Trap words

False statements on the exam often repeat a true rule and change a single word. These are the Italian words to read carefully in this topic. They stay in Italian because that is how they appear on the exam.

Words for this topic

spazio di reazione
reaction distance. The metres covered between seeing a hazard and pressing the brake. It is never zero.
At 100 km/h one second of reaction covers about 28 metres.
spazio di frenata
braking distance. The metres covered from when the brakes act until the car stops. It grows with the square of speed.
Twice the speed means roughly four times the spazio di frenata.
spazio di arresto
total stopping distance. Reaction distance plus braking distance; not the same as braking distance alone.
«The spazio di arresto is the same as the braking distance»: false.

Words that appear in every topic

sempre
always. An absolute: the statement is true only if there is no exception at all.
«Keeping to the limit sempre (always) guarantees a safe speed»: false, in fog or on ice you go slower.
solo, soltanto, esclusivamente
only. It rules out every other case, so a single exception makes the statement false.
«The children sign is placed soltanto (only) outside primary schools»: false, it also appears near parks and sports grounds.
mai, in nessun caso
never, in no case. The statement is true only if the behaviour is not allowed in any situation.
«A driver with priority may in nessun caso (never) give it up»: false, they may, as long as they make it clear.
ovvero
In the language of the Codice it means «or» and introduces an alternative. It does not mean «that is».
Emergency stop: the vehicle has broken down ovvero (or) the driver must stop because they feel unwell (art. 157). Two separate cases; either one is enough.
obbligatoriamente, è obbligatorio
compulsory. A duty: it is not enough for the behaviour to be allowed, it must be required.
«Overtaking on the left is obbligatorio (compulsory) even past a driver turning left»: false, in that case you pass on the right.
è consentito, è ammesso
allowed, permitted. A permission, not a duty. «È consentito» does not mean «è obbligatorio», and the reverse.
«It is consentito (allowed) to pass on the right a driver who has signalled a left turn»: true, and art. 148(7) actually requires it.
di norma, di regola
as a rule, normally. It states the general rule, which allows exceptions, so the statement does not claim to hold in every case.
«Outside built up areas warning signs are placed di norma (as a rule) 150 metres ahead»: true, and a panel gives any other distance.
anche
also, even. It stretches the rule to one more case; ask whether that added case really belongs.
«The no parking sign anche (also) bans stopping»: false, a brief stop is still allowed under a no parking sign.
automaticamente, di per sé
automatically, in itself. It suggests an effect that applies on its own, when the effect usually depends on a sign or a specific condition.
«In fog the motorway limit automaticamente (automatically) drops to 90 km/h»: false, the automatic cut applies to rain and snow.
qualsiasi, qualunque, in ogni caso
any, in every case. It generalises; look for the category or situation the rule leaves out.
«The safe distance is the same at qualunque (any) speed»: false, it grows with speed.
corsia
lane. The part of the carriageway wide enough for one line of vehicles (art. 3).
A two way carriageway (carreggiata) usually has two corsie (lanes), one for each direction.
carreggiata
carriageway. The part of the road for vehicles, made up of one or more lanes (art. 3). It does not include the verge or the pavement.
A speed limit applies to the whole carreggiata (carriageway), not only to the lane next to the sign.
banchina
verge, hard strip. The strip beside the carriageway and outside it, not meant for driving (art. 3).
Outside built up areas you park off the carriageway, for example on a suitable banchina (verge) (art. 157(3)).
fermata
stop. A brief halt to let people get in or out, with the driver present and ready to move off (art. 157).
Pulling in to drop off a passenger and leaving straight away is a fermata (stop), not a sosta (parking).
sosta
parking. A prolonged halt during which the driver may leave the vehicle (art. 157).
A divieto di sosta (no parking) does not ban stopping; a divieto di fermata (no stopping) bans parking too.
arresto
halt. An interruption caused by traffic, such as a red light or a queue. It is not the driver's choice (art. 157).
Stopping at a red light is an arresto (halt); no stopping ban prevents it.

Check yourself

Three statements on the topic. Answer and see straight away whether the rule has stuck. These answers are not saved.

Question 1 of 1

  1. Raddoppiando la velocità lo spazio di frenata raddoppia.

    Doubling the speed doubles the braking distance.

  2. Lo spazio di arresto è la somma dello spazio di reazione e dello spazio di frenata.

    Total stopping distance is reaction distance plus braking distance.

  3. La distanza di sicurezza è un numero fisso di metri, uguale a qualunque velocità.

    The safe distance is a fixed number of metres, the same at any speed.

Topic quiz: 22 statements

Untimed. After each answer you see the solution, the explanation, the trap words highlighted and a link back to the rule. At the end you get your score and can retest just the ones you missed.

Question 1 of 1

  1. La distanza di sicurezza deve consentire l'arresto del veicolo senza urtare quello che precede.

    The safe distance must let the vehicle stop without hitting the one in front.

  2. Raddoppiando la velocità lo spazio di frenata raddoppia.

    Doubling the speed doubles the braking distance.

  3. Lo spazio di reazione dipende dal tempo che passa tra la percezione del pericolo e l'azione sul freno.

    Reaction distance depends on the time between perceiving the hazard and pressing the brake.

  4. Su fondo bagnato la distanza di sicurezza può essere ridotta perché si frena prima.

    On a wet surface the safe distance can be reduced because braking is quicker.

  5. Nelle gallerie la distanza di sicurezza può essere ridotta perché il fondo è asciutto.

    In tunnels the safe distance can be reduced because the surface is dry.

  6. Un carico pesante allunga lo spazio di frenata del veicolo.

    A heavy load lengthens the braking distance of the vehicle.

  7. Mantenere una distanza ravvicinata dal veicolo che precede migliora la visibilità della strada.

    Staying close behind the vehicle in front improves the view of the road.

  8. Lo spazio di arresto è la somma dello spazio di reazione e dello spazio di frenata.

    Total stopping distance is reaction distance plus braking distance.

  9. A parità di velocità lo spazio di arresto è maggiore per un veicolo con pneumatici usurati.

    At the same speed the stopping distance is greater for a vehicle with worn tyres.

  10. A 100 km/h un secondo di disattenzione fa percorrere quasi trenta metri senza controllo.

    At 100 km/h one second of inattention means covering nearly thirty metres without control.

  11. La distanza di sicurezza va aumentata quando si segue un veicolo che impedisce di vedere la strada davanti.

    The safe distance must be increased when following a vehicle that blocks the view of the road ahead.

  12. Anche in colonna a bassa velocità occorre mantenere una distanza di sicurezza dal veicolo che precede.

    Even in slow moving queues a safe distance from the vehicle in front must be kept.

  13. Il tempo di reazione si allunga con la stanchezza, con l'alcol e con l'uso di alcuni farmaci.

    Reaction time lengthens with fatigue, with alcohol and with some medicines.

  14. Su ghiaia o su neve fresca l'ABS può allungare lo spazio di frenata rispetto a una ruota bloccata.

    On gravel or fresh snow the ABS can lengthen the braking distance compared with a locked wheel.

  15. La distanza di sicurezza va valutata anche in funzione della massa del veicolo e del carico trasportato.

    The safe distance must also take account of the mass of the vehicle and the load it carries.

  16. La distanza di sicurezza è un numero fisso di metri, uguale a qualunque velocità.

    The safe distance is a fixed number of metres, the same at any speed.

  17. A bassa velocità lo spazio di reazione è nullo.

    At low speed the reaction distance is zero.

  18. Chi segue troppo da vicino non è responsabile del tamponamento se il veicolo davanti frena bruscamente.

    A driver following too closely is not responsible for the shunt if the vehicle ahead brakes hard.

  19. Lo spazio di frenata dipende soltanto dalla potenza del motore.

    Braking distance depends only on engine power.

  20. Con scarsa visibilità conviene avvicinarsi al veicolo che precede per seguirne le luci posteriori.

    In poor visibility it is best to close up on the vehicle in front and follow its rear lights.

  21. Il sistema ABS consente di ridurre la distanza di sicurezza.

    The ABS makes it possible to reduce the safe distance.

  22. Lo spazio di arresto coincide con lo spazio di frenata.

    Total stopping distance is the same thing as braking distance.

What next

All exam topics

Educational content. For the official rules, see the Codice della Strada and legal notes.