How does pavement slickness change during rainfall?

The correct answer is that pavement becomes more slippery after several hours of rainfall. During the initial phase of rain, water can wash away dust, dirt, and oil residues from the road surface, which can create a temporary condition where the pavement may seem less slippery. However, as the rain continues, these substances can re-suspend and mix with water, forming a slick layer on the pavement. This mixture creates an increase in slickness, especially when enough rain has fallen to combine with the contaminants.

Additionally, after prolonged rainfall, the pavement can become slick due to the accumulation of water on the surface, which can lead to hydroplaning, particularly at higher speeds. Understanding this progression highlights the importance of adapting driving techniques during varying weather conditions, ensuring that drivers remain cautious as rainfall continues.