Rush hour—a misnomer, as it often lasts longer than a single hour—is a period of the day when traffic congestion on roads and crowding on public transportation is at its peak. These periods usually correspond to the start and end of the typical workday, when most people are commuting. Thus, there tends to be both a morning and an evening rush hour. Some areas even have a lunchtime rush hour. What system have some cities, such as São Paulo, Brazil, instituted to help curb rush hour traffic? Discuss