Potholes begin after snow or rain seeps into the soil below the road surface.
The moisture freezes when the temperature drops below freezing, causing the ground to expand, rise and push the pavement up. As temperatures rise, the ground returns to normal level before the pavement does, creating a cavity, or pocket between the ground and the pavement. When cars and trucks drive over the cavity, the surface cracks and falls into the hollow space. Thus, another pothole is born. Copyright 1999-2001 Kentucky Transportation Cabinet.