Q: Passage: A rush hour (American English, British English) is a part of the day during which traffic congestion on roads and crowding on public transport is at its highest. Normally, this happens twice every weekday -- once in the morning and once in the afternoon-evening, the times during which the most people commute. The term is often used for a period of peak congestion that may last for more than one hour.

Question: Based on this passage, when does heavy traffic occur in urban cities?
Let's give stream of consciousness below
To answer the above question, the relevant sentence is: Normally, this happens twice every weekday -- once in the morning and once in the afternoon-evening, the times during which the most people commute. So the answer is twice every weekday -- once in the morning and once in the afternoon - evening , the times during which the most people commute.