<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (February 2007) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (February 2007) (Learn how and when to remove this template message) </Td> </Tr> <P> 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 . </P> <P> The term is very broad, but often refers specifically to 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 . By analogy to vehicular traffic, the term Internet rush hour has been used to describe periods of peak data network usage, resulting in delays and slower delivery of data packets . </P>

When does heavy traffic occur in urban cities