Anti-lock braking systems in cars (ABS)

What are anti-lock braking systems (ABS)?

The main purpose of ABS is to prevent skidding where loss of steering and control result from locked wheels when braking hard. Such systems are now fitted to many new cars. This is intended to provide additional steering in the emergency situation, not to decrease stopping distances.

Casualty reduction effect?

A meta-analysis of research studies shows that ABS give a relatively small, but statistically significant reduction in the number of crashes, when all levels of severity and types of crashes are taken together. There are statistically significant increases in rollover, single-vehicle crashes and collisions with fixed objects. There are statistically significant decreases in collisions with pedestrians/ cyclists/ animals and collisions involving turning vehicles. ABS brakes do not appear to have any effect on rear-end collisions. However, while injury crashes decrease (-5%), fatal crashes increase (+6%) [15]. A recent study, however, indicates that anti-lock brakes may not contribute to crash prevention at all [13].

As with other forms of braking, the effectiveness of anti-lock braking depends upon road user behaviour. A German study found that ABS brakes can lead to changes in behaviour in the form of higher speeds and more aggressive driving [4]. It has also been suggested that the results to date may also be partly due to lack of knowledge or incorrect assumptions amongst car drivers about how ABS brakes actually function [9].