When studying the Highway Code for your driving test you will certainly have come across the braking distances for cars, and probably learnt them off by heart. That said once you’ve got your driving licence, certain facts that you’ve learnt for the theory portion of the test can slip your mind.
Back to basics
The safest way to brake in a vehicle is early and gently, pressing lightly on the pedal rather than slamming it down. By keeping an eye on any potential hazards on the road you should have a better idea about what to expect. The driving theory test now even includes a hazard perception module.
Brakes are less effective after travelling through water. It is therefore advisable to test them as soon as possible after going through a deep puddle, flooding or ford. If they have become wet then applying a little pressure to them while driving slowly should dry them out.
The emergency stop
It’s all very well knowing the ideal way to brake is early and gently but sometimes sudden and unexpected hazards are unavoidable. During your driving lessons you will have been taught how to brake safely in an emergency, but it’s important to consider that the length of time it takes to actually stop depends on several factors:
It takes your body time to react to something you’ve seen. This is why the maximum time it takes to stop is made up of thinking time and braking time combined. At a higher speed it will obviously take longer for your car to decelerate. Larger vehicles take longer to stop as they have more momentum. Icy and wet weather affect the condition of the road and will increase your stopping distance.
Leave a safe distance
Given all the potential factors listed above it is important to leave a safe distance between you and the vehicle in front at all times. Sometimes motorways employ chevrons painted on the road to show how far apart vehicles should be.
As a general rule the Highway Code suggests that on a normal road you’ll need two seconds to stop, faster roads need four seconds and on wet or icy roads you’ll need even more. You can check this by using a signpost or chevron as a marker and counting "one elephant, two elephant" to see how close you are.
If, like many new cars, your vehicle has an Anti-lock Brake System (ABS) then details of how best to brake should appear in the owner’s manual. Remember ABS is designed to help to control the car, you shouldn’t rely on it to make the braking distance shorter.
The nitty gritty
So how do the numbers stack up? The Highway Code uses a 4m car as an example. At just 20mph they estimate you will travel for 6m just thinking, then another 6m braking. When you take that into account, hazards may be closer than they appear. The braking distances for other speeds are below:
Speed Stopping distance
30mph 23 metres
40mph 36 metres
50mph 53 metres
60mph 73 metres
70mph 96 metres
It’s a lot of detail to remember, and once you’re behind the wheel those hours spent poring over the Highway Code can feel like a long time ago. That said you’ve learnt it once, so keeping these distances in your mind could mean the difference between an accident and a near miss.