Traffic congestion is a condition on any network as use increases and is characterized by slower speeds, longer trip times, and increased queueing. The most common example is for physical use of roads by vehicles. There it occurs when traffic demand is greater than the capacity of a road (or of the intersections along the road). Extreme traffic congestion, where vehicles are fully stopped for periods of time, is colloquially known as a traffic jam.There are several main causes of traffic congestion. The prime cause is simply a volume of traffic too high for the road capacity, but there are a number of specific circumstances which cause or aggravate congestion - most of which reduce the capacity of a road at a given point or over a certain length, while others increase the number of vehicles required for a given throughput of people or goods.
