35.149. The braking distance on the road immediately after rain:
UAГальмівний шлях на дорозі одразу після дощу:
This is an exam question from the Traffic Rules of Ukraine about road safety in conditions of changed road situations, when the surface becomes wet and slippery. In such situations, the driver must understand how braking efficiency changes in order to timely adjust speed, following distance, and driving style to avoid accidents.
The question tests knowledge of sections 12 "Speed of movement" (item 12.1) and 13 "Distance, interval..." (item 13.1) of the traffic rules, as well as the general obligation to be attentive and respond to changing conditions (item 2.3). Immediately after rain, the coefficient of tire grip with the road decreases: water mixes with dust, dirt, and oil residues, forming a slippery film, and with a sufficient amount of water, partial "floating" of the wheels is possible. That is why a greater distance is required to stop from the same speed than on dry asphalt, and this is directly taken into account during the theoretical exam.
The analysis of the options in this exam question is simple: the statement about the increase in braking distance corresponds to the real conditions of a wet surface and the requirements of the traffic rules regarding the choice of safe speed and following distance. The option about reduction contradicts the physics of grip, since on a slippery surface the tires "hold" the road worse. The option about no changes is also incorrect, because even a short-term deterioration in grip after rain noticeably affects the stopping distance and requires a more cautious driving tactic.
Clause 12.1 (Section 12 "Speed of movement")
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.
Explanation of application: immediately after rain, the wheel grip with the surface is worse (the surface is more slippery), so to maintain control and the possibility of a safe stop, a lower speed is required, and the actual braking distance becomes longer.
Clause 13.1 (Section 13 "Distance, interval, oncoming passing")
Depending on the speed, road situation, characteristics of the cargo being transported, and the condition of the vehicle, the driver must maintain a safe distance and a safe interval.
Explanation of application: on wet/slippery surfaces, the braking distance increases, so the driver must increase the distance to avoid a collision in case of braking.
Clause 2.3 (subclause "b", Section 2 "Duties and rights of drivers of motor vehicles")
To ensure road safety, the driver is obliged to: be attentive, monitor the road situation, respond appropriately to its changes, monitor the correct placement and securing of cargo, the technical condition of the vehicle, and not be distracted from driving while on the road.
Explanation of application: a change in the surface condition after rain is a change in the road situation, to which the driver must respond in a timely manner (in particular, by adjusting speed and distance due to the increase in braking distance).
Thus, the correct answer is "Increases.", given that according to the requirements of the Traffic Rules, the driver must take into account the road situation (in particular, the slipperiness of the surface after rain) when choosing a safe speed and distance, since in such conditions the grip with the road is worse and stopping requires a greater distance.
Immediately after rain, tire grip conditions on the road noticeably worsen. Water remains on the surface, and along with it, dust, dirt, and traces of oil rise up, making the surface slippery even where the asphalt appears smooth and “normal.” As a result, the wheels grip the road less effectively, which directly affects braking efficiency.
According to the meaning of the Traffic Rules, the driver must choose a safe speed taking into account the condition of the roadway and, if necessary, be able to stop the vehicle within the visible distance. When the surface is wet, a greater distance is required to reduce speed and come to a complete stop at the same speed than on dry asphalt. That is, the braking distance increases, and the driver should reduce speed in advance and increase the following distance.
A practical example is simple: if on dry asphalt the car confidently slows down when the brakes are applied, then immediately after rain, with the same brake pressure, early ABS activation, slight skidding, or “aquaplaning” of the wheels on the water film is possible. This means that the stop will occur later than expected, and therefore a greater distance is needed.
Thus, the correct answer is "It increases," because immediately after rain, tire grip with the surface decreases due to the water film and a slippery layer of dirt and oil residues, and a greater distance is needed to stop.