ABS is no cure-all

Dear The Citizen

There is no doubting that in a variety of situations, anti-lock braking systems offer both handling and stopping distance advantages over standard braking systems. The practical demonstrations on a skid pan never fail to impress users and spectators alike. However, what both the manufacturers and media are loathe to divulge is the fact that the obvious benefits under controlled conditions do not translate into the same benefits out on the roads. Crash data collected primarily in the United States and Germany and analysed by eminent traffic safety experts Leonard Evans (in his book Traffic Safety) and Rune Elvik and Truls Vaa (in their book Handbook of Road Safety Measures) shows that fatal crashes increase on vehicles fitted with ABS!

Cars fitted with ABS show significant increases in overturning crashes (between 22% and 55%), single-vehicle crashes (15%) and collisions with fixed objects (14%), resulting in an increase in fatalities of 6%. The figures are even worse for larger vehicles. Pick-ups, vans and MPVs fitted with ABS show a 14% increase in fatalities. The reasons for this are that drivers tend to drive faster and more aggressively in vehicles fitted with ABS and they tend to take more trips in unsavoury weather conditions. As Leonard Evans puts it, better braking can be used to increase mobility or safety. Crash data suggests that most people use it to increase mobility. In other words, given the advantage of better braking, the majority of motorists travel at higher speeds, maintain speed for longer before braking and complete more journeys in severe weather conditions. This all translates into increased fatalities. As an intelligent individual, it makes sense to purchase a vehicle with ABS, but collectively we are worse off for having the technology because in the hands of the general motoring public, it does more harm than good.

What it boils down to is this. Manufacturers are trying as they might to create cars that are foolproof, but we keep coming up with better fools. In most cases bad behaviour negates the benefits provided by the technology. Here are some important points to keep in mind about ABS:

The main purpose of ABS is to prevent skidding thus enabling the driver to retain steering and control of the vehicle when braking hard. The main purpose is NOT, as mistakenly believed by many, to reduce stopping distances.

The laws of physics are the main determinant of how fast a car can brake and not whether it has ABS fitted or not. Anti-lock braking systems are only as good as the ability of the vehicle and the driver behind the wheel. Fitting ABS to a car with pathetic braking ability does nothing for its braking ability except prevent the wheels from locking. Otherwise stopping ability and stopping distance remain poor. The stopping ability of a car is determined by the balance of the chassis, the quality and state of the shocks, suspension, tyres, brake pads, brake callipers and disks. The distance in which a car can stop is determined by the aforementioned as well as the reaction time of the driver, the weight of the car, the road surface, and the weather conditions. ABS offers no assistance in any of these areas. A top of the range luxury vehicle stops as quickly as it does because its chassis and mechanical components are above average, not because it has ABS fitted.

· ABS will not save you from your own recklessness or foolishness.

Motorists generally believe that they can derive maximum benefit from ABS without practise. ABS is automatic after all. What is to practise? But as Stevie Wonder so eloquently puts it, “when you believe in things that you don’t understand, then you suffer”. Just as with most other skills, practise makes perfect and motorists would be advised to take their own vehicles through various scenarios under controlled conditions to see just what to expect from ABS.

A large percentage of crashes involve little or no braking at all. ABS is irrelevant in such scenarios. Crash data has also shown that when emergency braking is required, the average motorist does not brake hard enough soon enough and so the manufacturers have tried to mitigate against this by designing systems that brake for the motorist either when sensors detect an impending collision or when sensors detect a faster than usual lifting of the foot from the accelerator.

There are certain circumstances under which ABS is actually a disadvantage – on gravel surfaces for instance where a locked wheel is preferable because of the extra retarding force applied by the buildup of gravel in front of the wheel . One other scenario where ABS is undoubtedly the cause of many fatalities is when making large panic steering movements at speed under braking. Consider the concerning increase in the number of crashes occurring on multiple lane highways where cars are coming across the median and colliding head-on with oncoming traffic. Because of the high speeds involved, the occupants of the vehicle veering across the median are usually killed, meaning that the authorities and media tend to report these crashes as unexplained . However, it doesn’t take much deductive reasoning to arrive at the conclusion that many of these crashes are in fact caused by poor driving coupled with an ABS fitted car. When a motorist travelling at speed on a highway brakes hard and then steers violently to avoid the obstacle ahead, the ABS prevents the wheels from locking and enables the vehicle to steer in the direction of the input – invariably across the median and into oncoming traffic. If the car didn’t have ABS, the driver would most probably have locked the wheels, lost all steering and ploughed straight into the car, person or object ahead with far less serious consequences than crashing head on into high speed vehicles travelling in the opposite direction.

In light of the above, is lack of ABS such a bad thing? Not if it causes the purchaser to drive slower, less aggressively, or less often in extreme weather and not if the vehicle lives up to manufacturer claims of class leading handling and braking.

Mark Erasmus