F is for Following Distance


What is your following distance?

This is also known as a ‘separation distance’. It refers to the gap that we leave between our vehicle and the vehicle in front.

It’s important that we leave a good gap in case anything suddenly happens in front – it gives us time to react and slow or stop safely. Road traffic collisions are often caused by vehicles following the vehicle in front too closely.

It’s essential that drivers are able to judge a good separation distance in all types of conditions – whether it’s bad weather, heavy road traffic, different road conditions etc.

Slow-moving traffic

Sometimes in heavy, slow-moving traffic, it may not be realistic to leave a large separation distance. This could waste valuable road space especially in queues, and as you’re moving slowly, you will be able to stop quicker anyway. Even so, your separation distance should never be less than your thinking distance.

Rule 151 of the Highway Code says

In slow-moving traffic. You should:

  • Reduce the distance between you and the vehicle ahead to maintain traffic flow
  • Never get so close to the vehicle in front that you cannot stop safely
  • Leave enough space to be able to manoeuvre if the vehicle in front breaks down or an emergency vehicle needs to get past
  • Not change lanes to the left to overtake
  • Allow access into and from side roads, as blocking these will add to congestion
  • Be aware of cyclists and motorcyclists who may be passing on either side

Stopping distances

Last week in our ‘Emergency stop’ blog we looked at stopping distances, which is also relevant to our following distances. Your overall stopping distance is made up of your thinking distance and braking distance.

Thinking distance – is the time it takes you to think and react to the incident. If you’re feeling tired or unwell, it may take longer for you to process and react.
Braking distance – is the time it takes from when you start applying the brakes, to when you actually stop.
You need to leave enough space between you and the vehicle in front so that you can slow down or stop safely if the vehicle in front suddenly brakes.

Stopping distances can depend on a variety of things, including

  • How fast you’re going
  • Whether you’re travelling uphill or downhill
  • The weather
  • The conditions of the road
  • The type and age of your vehicle
  • The condition of your brakes and tyres
  • The size and weight of your vehicle
  • Your ability as a driver, and your reaction times

Judging a safe separation distance

A good way to judge a safe separation gap is to use the ‘two-second rule’. This is measured by counting two seconds from when the vehicle in front passes a stationary object, to when you pass the same stationary object.

If you are still counting to two when you pass the stationary object, this means you are too close to the vehicle in front and you need to drop back to give yourself a safer separation distance. If you have finished counting to two by the time you pass the stationary object, this means you have a good, safe separation gap. You may find it easier to use shadows on the road as the stationary object.

Sometimes it can be difficult to count to two properly! This may sound silly, but some people may count to two quickly and some may count slower. A good way to get around this is to use the phrase ‘Only a fool breaks the two-second rule’ – this takes approximately two seconds to say!

If the road conditions are wet, you should double the two-second rule, making it four seconds. One phrase for this is ‘Only a fool breaks the two-second rule. When it’s wet on the floor, then make it four!’. (Personally I just say the two-second rule twice). Also, remember spray from the vehicle in front may make visibility even worse – consider leaving an even bigger gap so that you can see clearly ahead.

When the conditions are icy or snowy, you should times the two-second rule by ten, making it 20 seconds! We haven’t yet come up with a catchy phrase for this – so brownie points if you can find a good phrase that takes 20 seconds to say! 😊

What can I do if a vehicle is following too closely behind me?

When a vehicle is following you too closely (sometimes called “tailgating” or “being a space-invader”), gently ease off your accelerator and gradually increase the gap between you and the vehicle in front. If you have a bigger gap between you and the vehicle in front, should anything happen, you will have even more time to react and can brake more gradually, which will give the vehicle behind time to react too.

Pay it forward: If the vehicle behind steals your space, give it to the car infront.


Some motorways may have special chevron markings in the centre of the traffic lanes, spaced 40 metres apart. Keeping two chevrons between your vehicle and the one in front will provide a safe separation distance at 70mph. There will be signs advising you to check your distance.


Remember to keep your distance from the vehicle that you’re trying to overtake. This will give you a better view of the road ahead – especially if you’re trying to overtake a lorry. Also, remember that large vehicles and motorcycles need a greater distance to stop, so consider leaving extra distance between yourself and them.

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