Autumn brings not only colourful leaves, but also long periods of rain and slippery roads. Suddenly, the tyres lose grip, the steering wheel feels unusually light and the car no longer responds. Aquaplaning can occur within seconds and take every driver by surprise.
Aquaplaning – also known as hydroplaning – occurs when heavy rainfall prevents water from draining properly from the road surface. Normally, the tyres displace the water and thus ensure contact with the road. However, if the amount of water is too great, it pushes itself like a wedge between the road surface and the car tyres. The vehicle loses contact with the ground, and steering and braking commands are no longer transmitted. Control is lost, the brakes fail and, in the worst case, the vehicle skids.
Causes of aquaplaning
Several factors influence the development of aquaplaning:
Speed: High speeds increase the risk because more water has to be displaced in a shorter time. From around 80 km/h, the risk increases significantly, but aquaplaning can also occur at lower speeds. Therefore, speed and driving style should always be adapted to the weather conditions and sufficient distance should be kept from the vehicle in front.
Vehicle and tyre characteristics: The tread depth of the tyres plays a decisive role. The grooves drain water and thus enable contact with the road surface. The more tread there is, the lower the risk of aquaplaning. Tyre pressure should also be checked regularly, as both too high and too low air pressure can promote aquaplaning. Defective shock absorbers further reduce road holding and make it more difficult to control the vehicle.
Road conditions: In principle, aquaplaning can occur on all roads. However, motorways and (multi-lane) federal highways, where vehicles travel at higher speeds, are particularly at risk. Rainwater often cannot drain properly in dips, underpasses and ruts, so extra caution is required here. Manhole covers and road markings become slippery when wet and require the full attention of motorcyclists in particular. As a general rule, the rougher the road surface, the lower the risk.
Correct behaviour in aquaplaning
If aquaplaning occurs despite all precautions, the following behaviour is crucial:
- Keep calm and hold the steering wheel straight until the tyres regain contact with the road. Do not make any sudden steering movements!
- Take your foot off the accelerator and depress the clutch to avoid engine braking.
In vehicles with automatic transmission, do not change gears under any circumstances and only take your foot off the accelerator very slowly. - Do not brake. If it cannot be avoided, brake very gently, as heavy braking can cause the vehicle to skid.
- As soon as contact with the road is restored, reduce speed and continue driving slowly and with foresight. If necessary, stop at a suitable place to collect yourself and focus on continuing your journey.
Preventive measures
To prevent this from happening in the first place, you can look out for early signs of aquaplaning:
- Watch the spray and water splashing up from the wheels of vehicles in front of you – this shows how much water is on the road.
- Turn down the radio so that you can hear acoustic warning signals such as water rushing in the wheel arches or the engine roaring due to changes in speed.
- Watch for changes in the steering wheel – floating front wheels make it noticeably easier to turn.
- In vehicles with stability control (Electronic Stability Program, ESP), also keep an eye on the indicator lights.
To avoid panicking when aquaplaning occurs and to be able to assess the dangerous situation correctly, it is helpful to practise difficult driving situations in a safe environment – for example, as part of a driver safety training course offered by many automobile clubs.