On what type of road surface may anti-lock brakes not work effectively?

Question Topic: Safety margins

Mark one answer
Smooth
Loose
Firm
Dry

Anti-lock braking systems (ABS) will not work effectively when the car has poor contact with the road. When there is poor contact with the road, your tyres can lose their grip on the road. The risk is heightened when the road is wet and in other poor weather or road conditions. For example, if it has been snowing or there is gravel or dirt on the road. If you notice that the road has a lose, slippery or uneven surface you should adjust your speed down accordingly. To use ABS brakes safely you should apply firm and constant pressure until you reach a stop. Cars fitted with ABS brakes do not require you to pump the brakes.

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How do anti-lock brakes work?

ABS have been fitted in cars since the 1980s as standard. This is because drivers tend to slam brakes on during an emergency situation. In a car without an ABS this causes wheel lock and a loss of control over the steering. However, an ABS uses sensors to detect wheel speed. If wheel lock is detected by the sensors, the system kicks in and reduces the amount of braking taking place on the wheel/s that are starting to lock. This ensures there is better traction with the road, helps you to maintain control, and ensures you come to a stop sooner and safer.

Theory Test Question

So, did you give answering the example theory test question a try? Let’s take each answer in turn to consolidate your understanding:

Smooth

Wrong! On a smooth road surface your tyres will have good traction with the road surface and the ABS should work effectively.

Loose

Correct! When the road surface is loose, the tyres may have poor contact with the road. This may mean your anti-lock brakes do not work effectively. This is because the anti-lock will prevent the wheel from breaking below the surface and gripping causing your braking distances to be longer.

Firm

Wrong! ABS brakes should work effectively on firm roads as there will be good contact between the tyres and the road.

Dry

 Wrong! Dry conditions will not prevent anti-lock brakes from working effectively.

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