22 October, 2018

Wet and dry stopping distances…how different are they?

As a conscientious driver, it’s important to understand how long it takes for your car to come to a stop. But the distance it takes to stop, depends on a number of factors. Here is the official stopping distances as published in the Highway Code.

Car Stopping Distances


As you can see, the total stopping distance is made up of two parts, a thinking distance and a braking distance. But what are they?

Thinking Distance
As you’re driving along, you notice something in the middle of the road. You look at it and try to work out what it is. When you realise what it is, you decide whether you need to take action or not.

The time taken to complete all of this is called Thinking Distance.

Braking Distance
Having decided that you need to brake, the moment you apply the brakes to the moment the car comes to a stop is the braking distance.

When you add thinking and braking distances together, that’s total stopping distance.

But the figures published in the Highway Code are based on a dry road surface, not wet. In the wet, the braking distances can be doubled and can be up to ten times as long in snow and ice.

So what does that mean? If you’re travelling along at 30 miles per hour on a dry road, the Highway Code would suggest it takes you 23 metres to come to a stop. In the wet that could increase to 35 metres and in the snow or ice, your stopping distance can be as much as 149 metres.

But wait, there’s more. There are more factors that can extend your total stopping distance further. Tyres respond differently to the road surface, you only have to take a look at the material produced by tyre manufactures such as Goodyear, Michelin and Continental.

In addition, the time taken by the driver to react varies. The Highway Code assumes a driver see’s a hazard and reacts to it in around 0.6 to 0.7 seconds, which I think you’ll agree is incredibly quick. If you take a little longer to react, which it’s highly likely you will, your thinking distance increases substantially which in turn increases your total stopping distance.

Nicholas, founder of CompareNewTyres.com had this to say “When we’re driving along a road, we have to allow ourselves not only the time to deal with anything we’re presented with when we’re driving, but we also need a little reserve in the tank too, just in case our first plan doesn’t work.

The total stopping distances vary greatly and no two vehicles and drivers will stop in the same distance. You need to consider this when you’re driving, not only should you account for your stopping distances, you need to consider whether other drivers around you are as proactive as you are. If you see something you’re unhappy with, take a bit of speed off, because the more speed you take off now, the less you have to lose if it goes wrong”.