How Potholes Are Formed


Pavement age, weather and traffic loads work in combination to break down paving and eventually create potholes:

  1. All pavements flex slightly under traffic loads, particularly from heavy vehicles. As asphalt ages, it becomes brittle, and load flexing starts to cause surface cracking.
  2. Rainwater enters through cracks and is soaked up by the mix of rock, gravel or clay that forms the roadbed. Traffic loads pump water through the soggy bed.
  3. Asphalt sinks into the eroded roadbed and eventually cracks under vehicle weights. Surface holes are formed when chunks of asphalt break loose.
  4. Treatments such as hot or cold patching can temporarily smooth the surface, but unless the underlying roadbed is fixed the patch will eventually fail.
Diagram of road cracking
Diagram showing tire driving over cracks in road
Diagram showing pothole
Diagram showing patched pothole
Phase 1
Phase 2
Phase 3
Phase 4