What is traffic congestion

Traffic congestion is a condition on networks that occurs as use increases, and is characterized by slower speeds, longer trip times, and increased queueing. The most common example is the physical use of roads by vehicles. When traffic demand is great enough that the interaction between vehicles slows the speed of the traffic stream, congestion is incurred. As demand approaches the capacity of a road, extreme traffic congestion sets in. When vehicles are fully stopped for periods of time, this is also known as a traffic jam.