In which conditions are your anti-lock brakes most unlikely to prevent skidding?

Question Topic: Safety margins

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In foggy conditions
On loose road surfaces
At night on unlit roads
On dry tarmac

abs lightAnti-lock brakes are most unlikely to prevent skidding when driving on roads with loose surfaces. They may also be ineffective when driving in challenging weather conditions, such as in very wet weather. This is because, when water builds up between the tyre and the surface of the road, it can be possible to aquaplane. They may also be more unlikely to prevent skidding in snowy and icy conditions as contact with the road will be compromised. When driving in these sorts of conditions it is important to adjust your speed downwards accordingly. When using anti-lock brakes you should apply pressure constantly and firmly until you reach a stop. It is not necessary to pump the brakes when you use anti-lock brakes.

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How does and anti-lock braking system work?

Most cars have been fitted with an anti-lock braking system (ABS) since the 1980s. They were designed to deal with the classic problem of drivers slamming on the brakes when in an emergency situation. Without an ABS fitted, this causes the wheels to lock, decreases the driver’s control, and increases the chances of skidding.

When an ABS is fitted, it uses sensors to detect when wheel lock is occurring and adjusts the brakes accordingly to prevent it. In normal conditions, this ensures improved traction with the road, more control, and less chance of skidding. However, on loose surfaces and challenging weather conditions skidding and aquaplaning can be more likely.

Theory Test Question

Did you try answering the theory test question: In which conditions are your anti-lock brakes most unlikely to prevent skidding? Let’s consider each of the answers in turn to check your understanding:

In foggy conditions

Wrong! Your anti-lock brakes will not be negatively affected by foggy conditions. You should also adjust your speed downwards in foggy conditions which will help to prevent skidding.

On loose road surfaces

Correct!  Anti-lock brakes can be ineffective when driving on loose road surfaces. This is because there is poorer contact between the tyres and the road.

At night on unlit roads

Wrong! Anti-lock braking systems will not be more unlikely to prevent skidding because of lighting conditions.

On dry tarmac

Wrong! In dry conditions, your anti-lock brakes should work effectively. It is in wet weather, snow, or poor road conditions when they are least likely to prevent against skidding.


In section 5 of the official DVSA guide to driving, it states:

Anti-lock brakes

ABS brakes help you to continue steering while braking, but on wet or slippery roads this will be less effective. The brakes are only as good as the tyres’ grip on the road.

Don’t assume that ABS brakes will reduce the stopping distance.

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