Braking distance and speed: reaction time, gap and exam questions

Stopping distance is reaction distance plus braking distance. At 100 km/h you cover about 28 m per second, and doubling your speed makes braking about four times longer. A gap in metres applies only on motorways, expressways, in tunnels and when overtaking two-wheelers (1 m); elsewhere it must rule out a collision.

What the stopping distance is made up of

The stopping distance is the sum of two sections. The first you cover during the reaction time: from the moment you notice an obstacle until the brakes start to work. The second is the braking distance, the section from the start of braking to a standstill. The first depends mainly on the driver, the second on speed, the road surface and the condition of the vehicle.

The Road Traffic Act (Prawo o ruchu drogowym) does not define the stopping distance or give a formula. The basis is art. 19(1): you drive at a speed that lets you keep control of the vehicle, taking into account the terrain, the condition and visibility of the road, the condition and load of the vehicle, the weather and the volume of traffic. In addition, art. 19(2) point 3 requires you to keep the gap needed to avoid a collision if the vehicle in front brakes or stops.

The question catalogue asks about factors with a direct influence on the length of the stopping distance. The answers are the driver's reaction time (questions 3651: A and 10056: C) and speed and the condition of the road surface (3652: B). The mass of the passengers, the mass of the vehicle and the amount of fuel are distractors in these questions.

How many metres you cover per second: 100 km/h is about 28 m

The simplest conversion in the catalogue: at 100 km/h a vehicle covers about 28 metres per second (question 13594, answer YES). It follows from arithmetic: 100 000 m divided by 3600 s. The same arithmetic gives the other values.

One second of delayed reaction at 120 km/h, the speed permitted on a dual-carriageway expressway, is about 33 m travelled without braking. That is why question 13593 (whether a 1-second delay in reacting at the speed permitted on an expressway can increase the stopping distance by tens of metres) has answer YES. The full limits for every type of road are in our article on speed limits and fines.

Twice as fast, four times as long

The braking distance does not grow in proportion to speed. Doubling the speed makes it roughly four times longer. The catalogue asks about this in several variants: question 3634 (how doubling the speed affects the length of the braking distance) has answer B (four times), question 10059 answer C (4 times), question 6346 answer A, and 8995 answer A (the braking distance gets longer as speed increases).

We do not give our own tables of metres for specific speeds here, because there are none in the Act or the catalogue. For the exam the relationship is enough: doubling the speed means about four times longer braking, and on top of that comes the reaction distance, which grows in proportion to speed.

What lengthens the stopping distance: table of factors

Question 7461 (in which conditions the braking distance is longest) has three answers: a dry, a wet and an icy surface. The correct one is C, icy.

Reaction time: what lengthens it and how to shorten it

The total perception and reaction time is affected by visibility on the road and the complexity of the traffic situation (question 8972, answer B). The more that is going on around you and the worse the visibility, the later you spot a hazard and the further you travel before you start braking.

The simplest way to lengthen your reaction time is a phone in your hand. That is a separate offence with a 500 zł (PLN) fine and 12 points (as of September 2026), which we describe in our article on using a phone at the wheel. Tiredness works in a similar way, though the rules give no figures here: treat it as practical advice and plan breaks before you start nodding off.

You also shorten your reaction time by looking far ahead of the bonnet and by anticipating. When you see cars braking two vehicles ahead, you lift off the accelerator before the brake lights come on directly in front of you.

Emergency braking with and without ABS

In a car with ABS you brake in an emergency quickly and hard, pressing the pedal all the way down, and you do not release it when the system kicks in and the pedal starts to pulse. The catalogue tests this in questions 6379: A, 7710: A, 3858: B, 3859: A and 6338: C (the shortest braking distance with ABS: pressing the pedal all the way down).

ABS prevents the wheels from locking, keeps the car steerable and helps you keep control while braking (4495: A, 7463: B, 3860: A, 6339: A). It does not shorten the braking distance in all conditions. Question 6337 on the function of ABS has answer C (it makes it easier to steer around obstacles while braking); answer A (it shortens the braking distance in all conditions) is a distractor.

Without ABS, braking too hard locks the wheels and leads to a loss of steering control (3857: B). If the ABS fails on a slippery surface, you brake in pulses (10054: A). How ABS, ESP and the other systems work is explained in our article on car safety systems.

What gap the rules require: table

On an ordinary road the rule gives no figure. The gap must be sufficient to avoid a collision if the vehicle in front brakes or stops (art. 19(2) point 3), and you set it according to the speed of the vehicles (10034: A, 6351: A). Question 13042 picks exactly that wording (answer B), and the answers with a number of metres at 60 km/h or with any gap you like are distractors. A numerical minimum exists in only a few places.

For too small a gap on an ordinary road the fines tariff has no separate amount. The items cover motorways, expressways and tunnels (items 153 and 83), the gap for overtaking vehicles (item 82) and overtaking without a safe gap (item 91). The details of the rules on motorways are collected in our article on driving on motorways and expressways.

Two questions on lateral clearance go beyond numbers. When passing parked cars you allow for a door being opened (8220: YES), and when passing a drunk cyclist you increase the gap (3367: YES).

The two-second rule: advice, not law

The two-second rule is practical advice that appears neither in the Act nor in the catalogue. You pick a reference point, say a post or a sign, and count how much time passes from the moment the vehicle in front passes it until you pass it yourself. If it is less than two seconds, you increase the gap. Counting takes a moment, and after a few days you do it by reflex, without looking at a clock.

The arithmetic shows that the rule is more cautious than the law. At 100 km/h you cover about 28 m per second, so two seconds is about 56 m. The statutory minimum on a motorway and an expressway at that speed is 50 m. On a wet or icy road you increase the gap, because the braking distance grows and the rules require you to adjust speed and gap to the conditions.

Traps in the questions and a cheat sheet with answers

Three types of distractor come back regularly in this topic:

1. The mass of the passengers, the mass of the vehicle and the amount of fuel as a factor directly affecting the stopping distance (3651, 3652, 10056). The correct answers are reaction time, and speed and the condition of the road surface.
2. ABS supposedly shortening the braking distance in all conditions (6337). ABS keeps the car steerable, and the shortest distance with ABS comes from pressing the pedal all the way down (6338).
3. A gap in metres on an ordinary road (13042). A figure for the gap to the vehicle in front applies only on a motorway, an expressway and in a tunnel; elsewhere the gap must be enough to avoid a collision. A separate figure is the 1 m of lateral clearance when overtaking two-wheelers and a column of pedestrians (art. 24(2)).

The pattern of mistakes that cost points in the theory test is described in our article on the most common mistakes in the theory test. You can practise all the questions on this topic on the list of category B questions, and under exam conditions in the category B mock exam. A practical tip for the road: when the car in front passes a sign, start counting; if you pass it before two, just lift off the accelerator.