Highway Code Stopping Distances are a favourite among theory test question-setters. Sometimes you can take a lucky guess – but a whole plethora of factors can affect the stopping distance of a car at any given speed.
Popular Highway Code questions on the theory test include quizzing you on stopping distances on ice, in wet conditions, at 60mph and then at 30mph. Some people have been known to get every question on stopping distances that the DSA offer – after all, the choice of 50 questions is randomised.
You can understand why the DSA think knowing your stopping distances is so important (you can download the stopping distances pdf here). If you know how long it will take you to stop at 30mph, you know when you need to start braking for the red light ahead. You also know (on a more macabre note) exactly how quickly you need to stamp on the brake to avoid hitting a child that runs out in front of you (as a general rule, ‘immediately’ is the preferred answer).
It also gives you an understanding of how dangerous driving can be in wet or icy conditions. When there’s a lot of water on the road surface, you’ve got much less grip (or traction, as it’s technically called) and therefore less control. Driving along normally, this isn’t a problem. Once you hit the brakes though, that grip goes almost completely – and your control with it. Car tyres use the friction with the road surface to help them slow the vehicle down, and if that friction isn’t there…
Broadly speaking, stopping distances double when you’ve got wet conditions. On ice it’s worse: they’re ten times greater. So if, driving on a normal sunny day at 30mph, it takes you 23 metres to stop (that includes the time it takes you to see the hazard, process it, and react), then in icy conditions it could take you as much as 230 metres to stop. 230 metres is the same distance as the length of two full size football pitches – and that’s just at 30mph. Think about the distance it could take at 50, or even 60mph. What about if you’re speeding? 80mph?
Highway Code Stopping distances, therefore, give drivers both a sense of the danger they can pose to other people, as well as the dangers that speeding – or ignoring the road conditions – can create.
Make sure you can prove that you’re in full control of your car. Know your Highway Code stopping distances – not just for the theory test, but so that when you’re on the roads for real, you can make informed, intelligent choices about how you drive.
Here's an image to give you an idea of stopping distances but you can download the Highway Code Stopping Distances pdf here.