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Safe Distance Between Cars

The advice in this article uses information from UK law and the highway code.

You should always drive with a minimum distance between you and the vehicle in front of you. This will allow you enough time to come to a safe stop if something happens that causes that vehicle to brake suddenly.

The Two Second Rule

To maintain a safe distance during normal driving, leave a two second gap between you and the car in front of you. This applies at any speed - choose a fixed point and count two seconds (0, 1, 2). If you reach that point before you reach 2 seconds, slow down a little to increase the gap, then measure the time again. The gap you leave will get larger the faster you go.

There are times when a two second gap is not enough.

  • When driving a large vehicle or a motorbike, which may need more space to stop, leave a 4 second gap.
  • If you're travelling behind a large vehicle, leave a 3 second gap, which will allow you to see around the vehicle and more of the road ahead.
  • When driving on wet or damp roads, leave a 4 second gap.
  • When driving on icy or snow-covered roads, leave an 6 second gap.
When in heavy traffic

When you're driving at slow speeds in queueing traffic, you should leave at least the "thinking distance" appropriate to the speed you're travelling.

The thinking distance that applies is roughly equivalent to one car's length for every 10 miles per hour. Ensure you maintain this distance at speeds below 20mph in slow moving, heavy traffic.

Minimum distance when stopped

If you need to come to a complete stop in heavy traffic, such as at traffic lights or a junction, you should leave a gap between you and the car in front that is large enough to see at least 15cm of the road surface.

If you stop in a tunnel, ensure you leave at least a 5 metre gap between you and the car in front. This ensures there is adequate space for people to move in between cars if an emergency requires the tunnel to be evacuated.

References

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