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So many road traffic accidents are caused by drivers driving too fast and too close to the vehicle in front. A driver needs to be able to judge a safe separation distance at all times, in all kinds of traffic, in all weather and road conditions.

It is much safer for you and the people in front, and your passengers. Plus, if you hit the car in front of you, you are considered to blame. You have no choice as to the space left behind you, but you can control the amount of space in front.

Tailgating – what is that?

Driving extremely close to the car in front is called Tailgating, and is particularly dangerous. If you are being tailgated by someone, then gently ease off the gas and allow the space in front of you to increase. You really don’t want to put yourself in a position where you have to brake from being too close to the car in front. Allow plenty of safety margin. If the tailgater is still close behind and happens to hit you in the rear, then, if you have left plenty of space in front of you, your vehicle will not impact the one in front, possibly preventing a major pile up. It also makes the insurance situation a little less complicated.

What exactly are Separation Distances?

Separation distances are safety margins or empty road between you and the vehicle in front.

Think about what happens as a pedestrian, when you are walking close behind someone on the street, and they stop suddenly, for some reason or other. What happens? You bump into them, or take a sideways swerve to avoid bumping into them.

However, if there was more than just a couple of feet between you and this person, you would notice him stopping in good time to avoid him safely.

This is how it works on the road, too.  If we follow too closely to the vehicle in front, we leave no time and no space for things to change rapidly. Leaving you having to do an emergency stop or dangerous avoidance manoeuvre, in order not to hit the back of his car. And even this is not guaranteed. Too close means trouble waiting to happen.

So what should we do?

It is generally a good idea on urban and suburban roads, to give plenty of space in front. For example, on dry roads, you can leave approximately 1 metre (1 yard) for every one mile per hour, of your speed.
At 30 mph you will be 30 metres away from the guy in front. Enough to encompass the suggested overall stopping distance published in the Highway Code.

What are Overall Stopping Distances.

The Highway Code contains a chart showing overall stopping distances as illustrated below.

These are distances a car travels, over the time it takes for you to bring the vehicle to a full stop. These distances are for a well maintained car, with good brakes and tyres, an alert driver, and a dry road, in daylight.

You need to leave enough space for this to happen safely. As the Highway Code suggests, at 30mph your car will take approximately 23 metres to come to a stop. This is made up of thinking distance (the time it takes for you to activate your brakes, and the distance you have travelled before they start to affect the speed of the car downwards), and braking distance (the time/distance it takes to come to a stop).

In general think of more speed = less time, and, less speed = more time.

So, overall stopping distance at 30 mph (if you leave 1 metre for every 1 mph), will leave you plenty of space to brake and stop should you need to, without impacting the vehicle in front, or having to make a dangerous swerve or lane change, and reduces the chance of a potentially disastrous skid.

Stopping Distances depend on:

  • How fast you are travelling
  • Whether you are on a level road, or a hill going up or down, and the steepness of that hill.
  • Weather, is it good and dry, or is it wet or icy
  • Tyres, are they good tyres and properly inflated, or worn or badly inflated
  • Brakes, are they working well, are they stopping you in a straight line.
  • Your ability as a driver, are you ill, tired, on medication, have drunk alcohol, are distracted, all of these can affect your reactions when applying brakes.

Separation distances are essential to allow you time to see and react appropriately to any potential or developing hazard.

Example Scenario

Just say you are close up behind something a little larger than an ordinary car: perhaps a bus or a commercial vehicle. If you are so close that you cannot see the driver’s side mirrors, then you are invisible to him, as he cannot see you. Plus, if the large vehicle has to stop suddenly then you have no chance of seeing the potential in the road ahead, and could very easily hit the rear of that vehicle.

So, stay back even more than normal, when travelling behind large vehicles. They can block your view of the road ahead, and reduce your ability to forward plan.


Sometimes it is not practical to allow and keep the separation distance, as in heavy, slow moving urban traffic, because of the limited road space available. But busy, slow moving traffic is the norm these days, and you must keep at least your thinking distance clear – and much more than that if the road is wet or slippery.

The overall stopping distance is really the only safe separation gap, anything less than this can be considered a risk.

The Two Second Rule

Some of you might have heard about this, but for those who have not, this is a simple technique for helping to judge separation distances. It is especially useful on faster roads, and motorways where speeds are considerable more than normal.

How to check the Two Second Rule

The driver of the following car must be at least 2 seconds behind the vehicle in front:

  • The driver is alert
  • The car is in good condition, good tyres, good brakes
  • The weather is dry.

Take a note of the vehicle in front when he passes a post or a bridge support, and then count 2 seconds. You should not arrive at the same spot before the 2 seconds are up.  If you are too close, then carefully drop back and retest the gap.

If you are tired, or driving a less than perfect car, or the weather is bad, then your 2 second rule should be extended to 4 seconds, or more. Always know your limitations.

REMEMBER…“Only a fool breaks the 2 second rule.”

Multiple collisions or pile-ups are caused by driving too close and too fast, which leads to drivers being unable to brake in time. You can avoid this by looking well forward, checking out how the traffic is performing, getting clues from large vehicles, looking for buses pulling in and out, taxis stopping and turning, junctions and pedestrians. Maintain that separation distance as much as you can. It is always better to drive defensively, allow yourself enough time for the journey, and arrive alive, but maybe a bit late, than to not arrive at all.



  1. It has nothing about how close a car should be behind you on a hill at a light. I want to know this as I had someone so close to me on a hill at a light I could see his eye colour.

  2. The advice when stopped for any reason be it lights or bus stops to either be able to see the rear wheels of the vehicle in front, remember that with a small car in front one can be only a couple of feet away and his wheels are seen whereas with a a bus one may have to be a lot further away. So the other advice is to be far enough away so as to allow another car to pass between you so that could be anything from about 8 ft to whatever one considers to be fair. A full cars length is considered to be about 12 ft., or 4 meters so that could be used. At lights many drivers behind the lead vehicle may start pulling away anticipating the lights changing and that really means that they are putting themselves into an insidious positron. Drivers should follow the vehicle in front only when it has set of as that leaves greater space for safety should that vehicle in front stop suddenly for whatever reason then a collision could be avoided.

    If there are any side roads just prior to the lights do not pull up and obstruct them. Allow space so that any vehicle wishing to turn in or out of that road has a clear path can do so. which to do so. This encourages more courtesy on the road and also enables the free flow so that others are not obstructed unnecessarily doen

  3. These are some great tips to keep in mind before taking a driving test, especially your point to keep a 2 second following rule. It’s important to develop defensive driving tests from the minute you start driving, even on your road test. It’s also important to get feedback after your test, even if you passed, on how you can improve and become a defensive driver. We can’t control other drivers, but we can control our own driving habits!

  4. The problem with the giving of safe space and by that i mean in all things including the space behind another vehicle is extremely important. So often I see drivers keeping less than the thinking distances with the vehicle in front. One of the problems is the highway Code. The 2 second rule is not easy to accommodate and at speeds in excess of 40 mph its not sufficient. Although the HC does say that one should at higher speeds give more than the 2 second rule it does not stipulate any other time period and it should be at least 3 seconds.
    Therefore at 50 mph [ 75ft per second ] in 3 seconds you travel 225 ft and the stopping distance in the HC is 175 ft so a good safe excess. At 60 mph one is travelling at 90 ft per second and in 3 seconds can travel 270
    ft and the stopping distance as shown in the HC is 270ft so that equal. At 70 mph on duel carriageways or motorways one is travelling at 105 feet per second in distance and in 3 seconds would travel 315ft which is the same distance in the HC and is also the distance between the marker posts which are situated as small posts on the side of the emergency slip road [ one hundred meters 315 ft ] That is also the distance of the three marker posts for coming of a motorway. That also means that any vehicle travelling at more than the legal speed limit should give far mire distance than the marker post in order to be safe. To many pile ups are created by two things inappropriate speed and inappropriate safe following on distance. If the speed is faster but the space is greater then pile ups will never happen.

    However as a learner one will not as yet get on a motorway and going back to the 2 second rule I said that it was not easy to accommodate. I find that some traffic is like that on the motorway. Although not speeding necessarily they do bunch up and if you actually allow one to overtake you which you should then you see that they are doing exactly the same thing to the car in front… tailgating. For yourself to keep a better and therefore safer following on distance just look at the lamp posts. Keep one lamp post apart from the vehicle in front. They are easy to spot and are on all town and village roads which have a 30 mph limit.

    Very shortly you will drive safer and with greater distance comes greater vision for you as to what is happening up ahead. No longer looking at the red lights of the brakes of the car in front but you can see ahead of that vehicle and know that he is to close to the vehicle in front of him and will need to brake at some point and therefore you are more prepared for anything that may happen and may be of danger to you.

    Not only that but by the giving of sufficient safe space other road users will be able to see you. If we presume that you are driving close to a HGV or bus in front and a car coming in the opposite direction wants to turn right it may see the bus or HGV but not you as you are hidden and the driver may presume [ wrongly] that the space behind the large vehicle is empty and once it passes it, it may turn into you path. At T junctions there would be more likely to pull out in front of you if they dont see you so by giving space you are making a great difference to the whole road safety scene. Not only that you find that you have greater control of the space in front and driving becomes a lot more relaxed. If you were only giving say 30 ft and a VW overtakes and cuts in on you and fills that space you will get annoyed and perhaps quite rightly so. If however you are giving good space about or above one lamp posts and the same thing happens then it will concern you less. You gave that safe space and another driver [ think idiot] has taken it up then so what. You have anticipated that it would happen and so you just slow a little and allow it to speed away from you and your own safe space is now clear again. This makes motoring a much safer and less stressful experience. It also benefits the car from all that acceleration and braking you were doing and making the petrol go further and reduces the carbon footprint or your car which make the air cleaner to breath.

    So give safe following on space and the benefits are many fold.