Following distance
Following distance is the gap between you and the vehicle in front. It gives you time to see a problem, react and stop safely.
Driving too close, known as tailgating, is one of the most common causes of rear-end collisions. The Highway Code gives a simple way to measure a safe gap.
By the end of this topic you can
- You can measure a two-second gap using a fixed point.
- You can increase the gap in rain, ice, fog and when following large vehicles or motorcycles.
- You can deal calmly with a driver who is following you too closely.
- You can rebuild your gap after someone pulls in front of you.
What you need to know and understand
- Allow at least a two-second gap from the vehicle in front on high-speed roads and in tunnels (Highway Code rule 126).
- Double the gap on wet roads, and allow up to ten times the gap on icy roads (rule 126).
- Never get closer than the overall stopping distance for your speed (rule 126).
- If you have to stop in a tunnel, leave at least a 5-metre gap to the vehicle in front (rule 126).
- Tailgating is dangerous and intimidating. It can be dealt with by the police as careless or dangerous driving (rule 126).
- If someone overtakes and pulls into your gap, drop back to restore a two-second gap (rule 168).
- In slow-moving traffic you can close up a little, but never so close you cannot stop safely (rule 151).
Measuring the two-second gap
The two-second rule works at any speed because the gap grows as you go faster. It is easy to check on the move.
- Pick a fixed point ahead, such as a sign, bridge or lamp post.
- When the back of the vehicle in front passes it, count "one thousand and one, one thousand and two" at a normal pace.
- If you reach the point before you finish, you are too close.
- Ease off gently and check again.
When two seconds is not enough
Two seconds is a minimum for good, dry conditions. In wet weather your stopping distance is at least double, so allow at least four seconds. On ice it can be up to ten times longer (rules 126, 227 and 230).
Leave a bigger gap behind large vehicles so you can see past them and so their driver can see you in their mirrors (rule 164). Remember too that large vehicles and motorcycles need a greater distance to stop (rule 126). In fog, rear lights ahead can give a false sense of security, so keep well back (rule 235).
If someone is too close behind you
You cannot control the driver behind, but you can make yourself safer. Increase the gap in front of you so you can brake more gently and give them more time to react. Keep a steady speed and do not brake suddenly to warn them.
If they want to pass, let them. Being overtaken calls for a steady course and speed, slowing if needed (rule 168). Do not let them pressure you into going faster than is safe or legal, and pull over somewhere safe if you feel stressed (rule 147).
Common mistakes
- Closing the gap on fast roads to stop others pulling in. Accept it and drop back.
- Keeping two seconds in the rain. Double it.
- Following a lorry closely to look for a chance to overtake. Drop back to see more.
- Speeding up or brake-checking a tailgater. Stay calm and steady.
Test yourself: Following distance
Answer each question, then read the explanation. Questions come in a random order each time.
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Sources: Highway Code rules 126, 147, 151, 164 and 168 (gov.uk); Highway Code rules 227, 230 and 235 (gov.uk). Independent guide, not affiliated with any licensing agency. Always check the latest official rules with the DVSA.