A rush hour or peak hour 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 a day—once in the morning and once in the evening, the times during when the most people commute. The term is very broad but often refers to specifically private automobile transportation traffic, even when there is a large volume of cars on a road but not a large number of people, or if the volume is normal but there is some disruption of speed