It's easy to assume that potholes are formed due to roads being poorly maintained but that is not usually the case. There are many factors that can cause potholes. The following stages demonstrate how a combination of weather and wear and tear is one of the major causes of potholes on roads. 

Stage 1

Water seeps in through cracks in the road surface, collecting underneath.

Stage 2

Over time, water continues to saturate the road base underneath, softening it.

Stage 3

When the water freezes, it expands and forces up the road surface. Traffic adds stress.

Stage 4

The cycle of freezing temperatures and thawing causes further cracks to appear.

Stage 5

Potholes also form during the summer months where the foundations of the road have deteriorated. Stress from traffic causes potholes in isolated locations.

Stage 6

Weight of traffic breaks up the road surface to form a pothole. Wear from traffic expands the hole.