Safety margins theory test questions

34 questions in this topic

How long it actually takes to stop, split into thinking distance and braking distance, and how much worse both get in rain, ice and fog.

The numbers are worth memorising. The questions frequently give you a speed and a condition and expect you to know the answer rather than estimate it.

Practise safety margins

Questions come from the DVSA revision question bank, used under licence. You will not see whether an answer is right until you have committed to one, which is the point. A sample of every topic is free and needs no account.

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The part of driving you can control

You cannot choose how the car in front brakes, what the weather does, or whether a driver emerges from a junction without looking. You can choose how much room you leave. That is what this topic comes down to: keeping enough space around the car that a mistake, yours or anybody else's, does not turn into a collision.

Why stopping takes longer than it feels

Stopping happens in two stages. First there is the moment between seeing a problem and getting your foot on the brake, during which the car carries on at full speed. Then there is the distance the car covers while it slows down. The first depends on you, and gets worse when you are tired or distracted. The second depends on your speed, the state of your tyres and how much grip the road is giving you, and it grows quickly. Double your speed and the braking part roughly quadruples.

That is why the gap to the car in front matters more than how good you think your reactions are. The Highway Code puts the minimum at two seconds of travelling time on a dry road. In the wet it wants at least twice that, and on ice your stopping distance can be ten times what it would be in the dry. If you reach a lamp post less than two seconds after the car ahead did, you are closer than the minimum, whatever the speedometer says.

Situations that catch people out

Somebody sitting close behind you is a problem you cannot fix by speeding up. Leaving a bigger gap in front gives you room to slow down gently, so they have time to react too.

Roundabouts and busy junctions are another. You follow the car in front towards the give way line, assume it is going to go, and look right for your own gap. It stops, and you roll into the back of it at walking pace. The fix is simple: do not move up until the car ahead has actually gone.

Then there are the conditions that creep up on you: an unlit country road where your headlights reach less far than you would need to pull up, a long downhill stretch with a full car, a bright low sun on a wet road. Each of them asks for the same answer, which is less speed and more space.

In the test

Expect to apply these ideas rather than just recite them. Learn the reasoning behind the numbers and the right answer is usually easy to spot.

How this topic appears in the real test

The car theory test is 50 multiple choice questions in 57 minutes, and you need 43 correct to pass. The questions are drawn from every topic, so you cannot skip one and hope. There is a hazard perception part as well, and you have to pass both on the same day.

These are revision questions rather than the questions you will be asked on the day.