As a result of melting snow and rain in the spring, motorists may fall victim to hydroplaning, which occurs when the tires lose contact with the wet roadway.
What conditions cause hydroplaning?
Hydroplaning can occur wherever water lies in puddles. Ruts or channelized depressions that can hold water, often form in the wheel tracks of heavily travelled roads. As well, between two consecutive turns, there is usually no lateral slope to the road, which causes water to collect. During heavy downpours, hydroplaning can occur at any time. Finally, when the run-off from melting snow or rain flows down an embankment, the conditions are ideal for this phenomenon.
It's a bad sign when the dark tracks left by the tires of the vehicle ahead of you suddenly disappear immediately behind the vehicle. Likewise, when the vehicle ahead of you sprays large amounts of water sideways, you should be careful. These two indicators require a certain degree of observation.
Although it is a good idea to watch the vehicles around you for clues, you must not ignore what your own vehicle can tell you. Hydroplaning is not far off if you have the unpleasant sensation that your front wheels are no longer gripping the ground. This same impression can occur during braking, particularly when there is no noticeable deceleration. With a front-wheel-drive vehicle, if you notice that the motor seems to be accelerating, despite the fact that you have not moved the accelerator, you know that you are starting to float. This phenomenon is not as noticeable in the case of a vehicle with rear-wheel drive. Finally, if you hear loud water noises in the wheel well, you know the situation is serious.
Water isn't the only cause
Although water is the principal cause of hydroplaning, other factors can also transform your vehicle into a boat. For example, speed plays a major role and deserves attention. Another very obvious cause is the depth of the layer of water: the danger increases proportionately with the depth.
The thickness and the design of the tire treads cannot be ignored either since the water, which forms a relatively thick layer on the road, must be pushed away if the tires are to remain in close contact with the surface. In other words, the tires must push the water to the front, to the back and, above all, to the sides. Unfortunately, a portion of the water remains on the surface since the contact is so brief, lasting only a few milliseconds, which is not enough time to push it out of the way. If the water is not drained at the sides or by means of grooves in the treads or if the grooves are too shallow, an incompressible layer of water forms, like a wave, in front of the tire. The tire will tend to drive up onto this wave, which separates it from the ground surface, in the same manner as a layer of freezing rain does.
Other factors can lead to hydroplaning. Even with identical treads, wide tires float more quickly than narrow ones do. Moreover, you must make sure that your tires are inflated to the pressure recommended by the manufacturer since this is an important factor when it comes to obtaining optimum water flow through the grooves of the treads. At the same time, the friction coefficient of the road also plays an important role. Finally, it appears that shock absorbers that are worn by 50% increase the risk of hydroplaning by 10% to 15%.
Can hydroplaning be avoided?
The golden rule is to decrease your speed when it's raining or when you suspect there may be water puddles on the road. In fact, tires that are travelling at high speeds on a wet road must move a lot of water very quickly in order to remain in contact with the ground. It is strongly recommended that you double your safety distances, both beside your vehicle and in front of it. Finally, drive slightly to the right or left of ruts in the road to reduce the danger.
Cruise control in wet conditions: not a good idea
Owner’s manuals now include a warning that cruise control should never be used on slippery road surfaces, including wet roads. The reason is simple: if excess water on the road causes the vehicle to start hydroplaning and cruise control is activated, the drive wheels will start to accelerate – the opposite of what you want to happen in this situation. Your vehicle may then start to skid out of control – with, potentially, more serious consequences. Many drivers have been involved in severe accidents because of this dangerous combination.
What to do if hydroplaning occurs despite precautions
Here is what you should do if your vehicle begins to hydroplane, despite your best preventive efforts. Try to keep the wheels aimed in the direction you want to go. Take your foot off the gas and then – but only if you are comfortable with this technique – shift into neutral and brake very gently, so as not to lock the wheels. Once the tires are in solid contact with the road again, shift back into gear to pick up speed. If you completely lose control of the vehicle, the best thing to do is line the wheels up straight and press as hard as you can on the brakes until the car comes to a stop.