These systems combine the wheel speed sensors used by the ABS system with other dynamic sensors and intervene to regain lost traction or stabilise the car. If the system detects one or more wheels spinning, it will intervene and try to regain grip.

 

It may do this in a number of ways depending on the system. It could:

 

Reduce the power output of the engine;

Apply braking force to the spinning wheel;

Transfer power from the spinning wheel to one with traction;

A combination of the above.

 

Different manufacturers have their own names and acronyms for these systems, so you need to know exactly what is on board by checking the owner's manual or asking the car dealer.

 

The next generation in traction control systems is electronic stability programs. Different manufacturers may have various acronyms for their systems but the most commonly used are ESP or ESC.

 

These really are fantastic and greatly assist the driver in the event of the car skidding. Basically, the system uses the ABS to correct the car’s course in both understeer and oversteer situations by applying brakes to the appropriate wheels.

 

Yaw sensors detect the sideways loss of control and the car applies braking force to bring itself back into line. This can be very helpful in a situation where the driver has had to take evasive action. Generally, this type of move is very tricky because the car may have been steered off the road in order to avoid the obstacle.

 

It is when the car is directed to come back on the road that an over-reaction can occur due to different grip levels and excessive steering movement. In this example, the system works out where the car is losing grip and takes corrective action. This is especially beneficial as the car returns to the road as the grip level changes yet again.

 

These systems will continue to evolve and increase the car’s stability during evasive manoeuvres.  They are a great safety back-up for the driver and reduce the likelihood of the car losing control.

 

But keep in mind that as good as these systems are, they too will have limitations. They are not infallible and should simply complement your own attention to your surroundings. Not replace them.

 

Drive Safely – Russell White, CARMA Road Safety Ambassador