Singapore and Hong Kong are both in areas which never experience freezing. The act of freezing and thawing of water in temperate climates is super harsh on road

Singapore and Hong Kong are both in areas which never experience freezing. The act of freezing and thawing of water in temperate climates is super harsh on roads - as water will seep into cracks and then expand when it freezes. It's the main reason why many roads are bad in many US cities like Chicago. Another reason might be due to regulations. I faintly recall hearing that European highways are built on an 18" base, whereas the US only a 12" base, but I'm sure it varies...