Is the road surface slippery when it just starts raining or after it has rained?
3 Answers
The road surface is more slippery when it just starts raining than after it has rained. Reasons why the road surface is more slippery when it just starts raining: Before it rains, the road surface accumulates many substances that can cause the wheels to skid, such as dirt, oil leaks from passing vehicles, and rubber residue left on the road surface due to friction between the tires and the ground. When rainwater moistens these substances, it acts like a thin layer of lubricant. Precautions for driving in the rain: Maintain good visibility. Turn on the windshield wipers promptly, and when the weather is dim, also turn on the low beams and fog lights. If there is frost on the front windshield, turn on the air conditioning and direct the cold air toward the front windshield. If there is frost on the rear windshield, turn on the rear windshield heater to quickly eliminate the frost and avoid obstructing the view of vehicles behind.
As a seasoned truck driver who's been on the road for years, I have to say that roads are extremely slippery right after it starts raining. When rainwater first hits the pavement, it mixes with accumulated dust and oil stains to form a muddy film - it feels like driving on ice. Last month when the heavy rain just started, my truck went into a skid and I had to immediately ease off the accelerator to regain control. Ironically, after about 15 minutes of heavy rain, the roads actually become safer as the rainwater washes away the grime - while still slippery, at least the tires can get some grip. Post-rain roads mainly have puddles which just require careful driving. So fellow drivers, when you see dark clouds approaching, slow down in advance. Those first few minutes when raindrops initially hit the ground are the most dangerous - don't rush during this critical period.
According to the changing patterns of road surface friction, roads do become more slippery right after rain begins. When rainwater mixes with long-accumulated oil stains, rubber particles, and dust on the road surface, it forms a lubricant-like film that can reduce the friction coefficient by nearly half. I personally tested this - at the same speed of 60 km/h, the braking distance right after rain was 15 meters longer than on dry roads. After continuous rainfall, as the water washes away these contaminants, leaving only standing water on the surface, the friction coefficient recovers by about 20%. However, in all rainy conditions, drivers should maintain at least double the normal safety distance, avoid sudden braking or sharp steering, and pay special attention to particularly slippery areas like reflective road surfaces and near road markings.
