ElI5: why is it that we tend to have more pot holes on street roads but not many on freeway or highways?

Question

ElI5: why is it that we tend to have more pot holes on street roads but not many on freeway or highways?

In: Engineering

Answer 1

There is probably a metre of engineered fill and a couple of hundred mm of asphalt of bound pavement on a highway vs 150-200mm of gravel and 20-30mm of asphalt on a public street.  Also better drainage to prevent water getting under the pavement.