Chapter V - Unfavourable road conditions, adhesion, skidding and aquaplaning

The road conditions are directly influenced by the weather and the carriageway.

Adhesion

Represents the phenomenon that occurs between the wheels of a vehicle and the running surface, thus enabling the movement of the vehicle.

The adhesion of the car depends on a series of factors over which we have more or less control. For example: the condition of the tyres, the quickness of steering manoeuvring, the travelling speed, etc.

Other factors, however, do not depend on us but on variables such as:

• the condition of the carriageway (moisture, mud, black ice, sand, loose snow, compacted snow, cobblestone pavement);
• the constructive solution of the car (front/rear traction, selectable 4x4, permanent 4x4);
• the weather conditions (strong wind, torrential rain, etc.);
• the special equipment of the car (ABS, Stability Control, ESP, ASR, etc).

Skidding

Is a consequence of low adhesion and incorrect manoeuvring of the motor vehicle.

The main cause of skidding is excessive speed, thus resulting in the loss of stability of the motor vehicle following excessive braking and the failure to adapt the speed to the slippery or wet carriageway conditions.

When the motor vehicle enters a skid you must lift your foot off the brake and the steering wheel must be moved gently in the opposite direction of the skid.

If the front wheels skid, the car will start to slide off the carriageway. In this situation it is recommended to slow down and keep control of the steering wheel so that the car goes straight.

If the rear wheels skid, the rear of the car will move, sliding in both directions. In this situation it is recommended to keep the steering wheel in the direction of the slide until the car no longer skids and the wheels come into contact with the road, then move the steering wheel in the opposite direction of the slide to straighten the car.

If all four wheels skid, the car will slide forward in a straight line as if it were a sled. In this situation it is recommended to keep calm and slow down gradually, lifting your foot off the accelerator, keeping control of the steering wheel in the direction of travel. Thus, when the wheels adhere again to the road you will be able to continue your journey.

Aquaplaning

Aquaplaning occurs when the car tyres no longer make direct contact with the asphalt because there is a film of water between the two surfaces.

Due to excessive speed or increased tyre wear, the water can no longer be quickly evacuated through the tyre channels.

The effect can be a loss of control of the vehicle by reducing the possibilities of manoeuvring or braking.