How potholes form
Potholes usually occur when water in roads freeze and thaw repeatedly, causing the surface to break up. They appear more frequently in late winter and early spring.
When water gets into the ground under the highway and freezes it will take up more space making the highway expand, bend, and crack, which causing it to weaken.
When the ice melts, the surface contracts and leaves gaps or voids under the highway, where water can get in and become trapped. If the water freezes and thaws repeatedly, the pavement will weaken and continue cracking.
As vehicles pass over the weak area in the road, it will cause the material to be displaced or broken down causing a pothole.