Every motorist has surely experienced the unpleasant sensation of the car suddenly lifting off the road surface in the pouring rain, leaving them feeling like a helpless passenger. Known as aquaplaning, this is a seriously frightening phenomenon, especially for less experienced drivers. But what exactly is aquaplaning and what can you do when it rears its head?
What is aquaplaning?
In very general terms, aquaplaning refers to a situation where one or more tyres are lifted off of the road surface by a layer of water. Aquaplaning occurs when the tyres in question can no longer displace the water underneath. The water then wedges itself underneath the tyres’ contact surface. A bow wave of water that cannot be dispersed quickly enough then effectively forms in front of the tyres. The result is a loss of adhesion.
The most dangerous part of this situation is that no driving or braking force can be exerted onto the road surface while the tyres are “floating” in this way. If no driving force can be exerted, a consequence of this is that no steering force can be transferred either. In the instant when aquaplaning occurs, the vehicle can no longer be controlled.
How does aquaplaning occur?
Aquaplaning is often perceived to be a state which develops very suddenly – one which can sometimes also be predicted, such as when driving through a puddle on a road or motorway. In actual fact, aquaplaning creeps up on drivers. The grip of the tyres’ contact surfaces slowly reduces from 100 per cent down to zero, causing the tyre to float.
Two factors in particular have an influence on aquaplaning and cause the tyres to lose grip in this way. Firstly, the depth of the standing water on the road surface and, secondly, the speed of the vehicle concerned. The composition of the road surface can also have an impact on the aquaplaning process.
Furthermore, the tyre tread plays a decisive part in diverting water from the contact surface. Studies conducted by German automobile club ADAC have shown that aquaplaning can even occur on slightly damp road surfaces with tread depths of around 3 mm or less, particularly when braking from a speed of roughly 100 km/h.
What do drivers need to do when the road surface is wet?
In the corresponding weather and road conditions, the ADAC automobile club recommends reducing the vehicle’s speed decisively and promptly in order to avoid driving situations where a loss of control is encountered.
The AVD automobile club recommends paying heed to two points when aquaplaning occurs:
- Avoid braking: take your foot off the accelerator and disengage the clutch
- Avoid heavy counter-steering: wait until the vehicle makes contact with the ground again