ABS, EBD, BAS and other active safety systems

These days there's a whole range of electronic devices and systems that significantly cut the odds of an accident and make driving easier. EBD, ABS, BAS — what are they, what good are they, and how do they work?

Most of these devices are aimed at the car's steering and braking system. ABS, or the anti-lock braking system, keeps the wheels from locking up under braking. The car doesn't lose control even when the pedal is slammed to the floor in an emergency. The system runs off sensors that read wheel speed and vehicle speed. If the car is moving but a wheel (or wheels) has stopped turning, the system releases the brake on the locked wheel. A great many cars are fitted with ABS today, and among the new cars you can buy on finance, most come with ABS as standard.

Brake assist (BAS) is an electro-pneumatic assistance system that kicks in during emergency braking. When the brake pedal is pressed hard but not all the way, brake assist boosts pressure in the braking system without waiting for the pedal to be pressed fully down. With a gentle press of the pedal, the system simply doesn't engage. The range of cars fitted with this system is still smaller than those with ABS, but given the demand, that clearly won't last. Opel, for instance, fitted this system to a popular model like the Opel Vectra, and Nissan did the same with the Nissan Almera.

Traction Control (the anti-slip system) works the opposite way to the ABS sensors. If some wheels are spinning faster than the others, the system instantly reads this as wheelspin. A pulse is sent to the braking system to slow down those wheels.

Electronic Brake Differential (EBD), an electronic differential lock, is fitted mainly to cars meant for off-road driving. In essence, it's an advanced anti-slip system that can, in theory, help pull a car free when one wheel is sitting on grippy ground and the rest are on smooth ice. The system brakes the wheels spinning faster and, through the differential, routes the surplus torque to the remaining wheels.

Electronic Stability Program (ESP), a system that prevents skids. It relies on the same sensors as ABS and the anti-slip system. When the system detects a mismatch between the wheels' rotation speeds and so on, it triggers braking on certain wheels, and the car is stabilised.

These systems are useful for amateur drivers; professionals, on the other hand, more often turn them off, preferring to control the car themselves without help (and sometimes interference) from electronic systems.