Traction control

Traction control system (TCS) /trak-shuhn kuhn-trohl sis-tuhm/ noun (countable)

A traction control system is an active vehicle safety feature that prevents the loss of traction of the driven wheels by detecting and limiting wheelspin during acceleration. This is the electronic nanny that stops you from leaving two long black lines of rubber on the road when pulling away from the traffic lights with too much enthusiasm. It is the sworn enemy of the boy racer and the guardian angel of the lead-footed driver on a wet roundabout. Using the same sensors as the anti-lock braking system, it constantly monitors for a spinning wheel and then intervenes like a disapproving schoolteacher, either reducing engine power or braking the offending wheel. It is a sensible invention that also removed a significant amount of juvenile fun from the act of driving.

The Full Story of the Traction Control System

For most of motoring history, the only thing stopping a car's wheels from spinning was the driver's right foot. Applying the right amount of power, particularly in a powerful car or on a slippery surface, was a delicate art form. Too little throttle and you were slow; too much and you were rewarded with a cacophony of screeching tyres and smoke, but very little forward motion. This was, for many, part of the fun and the challenge of driving. The engineers, however, saw it as a problem of inefficiency and instability that needed to be solved.

The solution was a natural evolution of the Anti-lock Braking System (ABS). Since cars were already being fitted with sensors to detect a wheel that was locking up under braking, it was a relatively simple step for engineers to program the same system to detect a wheel that was spinning too fast under acceleration. It was a clever piece of software piggybacking on existing hardware, and it gave birth to the first modern traction control systems in the late 1980s.

When the system detects wheelspin, it can intervene in two main ways. The cruder method is to tell the engine's computer to reduce power, either by retarding the ignition timing or closing the electronic throttle. Early systems did this with all the subtlety of a club hammer, suddenly bogging the car down and making a swift exit from a junction a jerky, frustrating affair. A more sophisticated method is to use the ABS pump to apply the brake to the individual spinning wheel. This slows the wheel down and, in a car with a normal differential, has the clever side effect of transferring the engine's power to the opposite wheel, which hopefully still has grip.

The technology reached its zenith in the fiercely competitive world of Formula One. In the 1990s and early 2000s, F1 traction control systems became so advanced they could manage the power delivery to the rear wheels on a corner-by-corner basis, allowing drivers to get on the throttle with what seemed like impossible aggression. It was a massive performance advantage, but it was also deeply controversial. Many purists argued that it devalued driver skill, turning the delicate art of throttle control into a simple on-off switch. The technology was so contentious it was banned, then briefly unbanned, and then banned again.

On the road, traction control followed the same path as ABS, trickling down from expensive German super-saloons to become a standard, and now legally required, feature on every new car as part of the wider Electronic Stability Control system. The nanny state had won. The ability to perform a celebratory "burnout" was sacrificed at the altar of safety and common sense.

For The Record

Is traction control the same as stability control (ESC)?

No. Traction control is a component of stability control. TCS works to prevent wheelspin under acceleration, primarily in a straight line. ESC is a much more complex system that works to prevent the car from skidding sideways in a corner, using the TCS and ABS systems to brake individual wheels and restore control.

Why do some cars have a "TCS Off" button?

For specific situations where a certain amount of wheelspin is desirable. For example, when trying to pull away in deep snow or mud, a little bit of wheelspin can help the tyres dig down to find grip. Performance drivers also often turn it off on a racetrack to allow them to control the car's attitude with the throttle.

Can traction control be too intrusive?

Yes, especially on early systems. They would often react too slowly and then cut the power too abruptly, making the car feel jerky and slow. Modern systems are much more sophisticated, intervening smoothly and often almost imperceptibly.

Does it work on front-wheel-drive cars?

Yes, it's very effective. While a powerful FWD car is less prone to dramatic fishtailing, it is very susceptible to spinning its inside front wheel when accelerating out of a tight corner. Traction control can brake this wheel, improving traction and reducing understeer.

Was traction control a Formula One invention?

While F1 developed it to an incredible level of sophistication, the concept first appeared on production road cars. The earliest systems were developed by Buick in the 1970s, but it was the German luxury brands in the late 1980s that pioneered the modern electronic systems that F1 would later adopt and perfect.