35.23. How should a driver act in case of loss of tire-road grip due to hydroplaning?
UAЯк має діяти водій у разі втрати зчеплення коліс з дорогою через утворення «водяного клина»?
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This is an exam question from the Ukrainian Traffic Rules about driving safety on wet surfaces and the phenomenon of aquaplaning (“water wedge”), when a film of water forms between the tire and the asphalt. In such a situation, traction drops sharply, the car responds worse to steering, and any sudden actions can lead to skidding. For the theoretical exam, it is important to understand that this is a typical “hazard to traffic” that requires an immediate reduction in speed.
The question tests knowledge of the section “Speed of movement” and the general requirements for driving according to the traffic rules, with reference to point 1.10 (definition of a traffic hazard), point 12.1 (choosing a safe speed considering road conditions), and point 12.3 (the obligation to immediately take measures to reduce speed). The correct algorithm in case of loss of traction due to aquaplaning is to smoothly reduce speed without sudden maneuvers, to allow the tires to regain contact with the road and restore control.
An analysis of the answer options shows the logic of the Traffic Rules: increasing speed only intensifies aquaplaning and prolongs loss of control, so this option is dangerous. Sudden braking with the pedal is also incorrect, because when the wheels are partially or fully “floating,” braking forces become uneven, and when traction is suddenly restored, the car may “jerk” and go into a skid. The safest action is to reduce speed by engine braking (smoothly release the accelerator, and if necessary, carefully shift to a lower gear), which meets the requirement to reduce speed without sudden actions and minimizes risks when traction returns.
Clause 1.10 (the term "Traffic hazard")
Traffic hazard — a change in the road situation (including the appearance of a moving object approaching the lane of the vehicle, or a change in the condition of the road surface, etc.) that threatens road safety and forces the driver to immediately reduce speed or stop.
The formation of a "water wedge" (aquaplaning) is precisely a change in the condition of the road surface that leads to loss of traction and control, i.e., to a "traffic hazard" as defined by the Traffic Rules.
Clause 12.1
When choosing a safe driving speed within the established limits, the driver must take into account the road situation, as well as the characteristics of the cargo being transported and the condition of the vehicle, in order to be able to constantly control its movement and drive it safely.
Wet pavement and the presence of a layer of water are elements of the road situation that require choosing such a speed at which control over the car is maintained and aquaplaning does not occur.
Clause 12.3
In the event of a traffic hazard or obstacle that the driver can objectively detect, he must immediately take measures to reduce speed up to stopping the vehicle or safely bypassing the obstacle for other road users.
"Water wedge" is a traffic hazard, so the Traffic Rules require an immediate reduction of speed. In practice, the safest way to reduce speed when traction is lost is by smooth engine braking (releasing the accelerator pedal/shifting to a lower gear without abrupt actions), so as not to provoke skidding when tire contact with the road is restored.
Therefore, the correct answer is "Reduce speed using engine braking," given that according to the definition of the Traffic Rules, a "water wedge" is a traffic hazard (clause 1.10), and when a hazard arises, the driver is required to immediately take measures to reduce speed (clause 12.3) and choose such a speed as to constantly control the movement of the vehicle (clause 12.1).
While driving on a wet road, the tire usually channels water away through the tread grooves and maintains a contact patch with the surface. But if the layer of water is significant and the speed is too high, the water does not have time to be displaced from under the wheel, and a film of water forms between the rubber and the asphalt. At this moment, the car seems to "float": traction drops sharply, the steering wheel may have almost no effect on the direction of movement, and any sudden actions become dangerous.
According to the requirements of the Traffic Rules, the driver is obliged to operate the vehicle at a safe speed, taking into account the condition of the surface, visibility, and other conditions, in order to be able to constantly control the movement and safely stop the car if necessary. That is why, when signs of aquaplaning appear (the response to steering is weakened, a feeling of "sliding" on water), the driver's primary task is to reduce speed, but to do so in a way that does not provoke a skid.
Pressing the brake pedal at the moment of "hydroplaning" is dangerous because the wheels partially or completely lack normal contact with the road. Because of this, braking can be uneven: one wheel may suddenly "find" the asphalt earlier than the others, a difference in forces will arise, and the car may go into a skid. It is equally risky to make sharp turns with the steering wheel: while there is no traction, the car is almost uncontrollable, and when contact is restored, sharply turned wheels can "jerk" the car to the side.
The safest way to reduce speed in such a situation is to gently release the accelerator and switch to engine braking, keeping the steering wheel straight in the direction of travel. Engine braking reduces speed without sharply locking the wheels, gives the car time to "push through" the water, restore tire contact with the surface, and regain control. If necessary, smooth downshifting is allowed, but without jerks.
Therefore, the correct answer is "Reduce speed using engine braking," because during aquaplaning, traction almost disappears, and it is the smooth reduction of speed without sharp braking that helps safely restore contact of the wheels with the road and control over the vehicle.