Traffic congestion

Congestion during road construction

Traffic congestion is when vehicles travel slower because there is too much traffic on roads. This makes trip times longer, and increases queueing. This is also known as a traffic jam. Congestion may result from a decrease in capacity, for example accidents on the road or roads being closed. Bad road layouts can also restrict capacity. Increased traffic, for example by many cars leaving a sports stadium at the same time, can also cause congestion.

Where congestion is common, for example because of commuting in big cities, several methods are used to relieve it. Cars may be banned in certain districts or certain times, or made to carry passengers or pay a fee, or people may use public transport, such as rapid transit, which travel independently of car traffic and are not affected by traffic jams.

Traffic Congestion Media

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  A traffic jam in Istanbul, and an opportunity for two simit vendors to sell food to drivers.

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  Speed-flow diagram for a highway, scales omitted. When the volume of vehicles per hour reaches 75%-100% of the road capacity, traffic flow shifts from free-flowing (green) to congested (gray) and both volume and speeds are reduced. The red ellipse represents rush-hour traffic.

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  Traffic jam - traffic on the Cairo-Assiut highway is blocked due to fog

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  Traffic congestion on Marginal Pinheiros, near downtown São Paulo. According to Time magazine, São Paulo has the world's worst traffic jams. Drivers are informed through variable message signs that display the prevailing queue length.

• Time lapse video of traffic congestion near HaShalom interchange in Highway 20, Israel

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  Congestion on a street in Taipei consisting primarily of motorcycles

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  India's economic growth has resulted in a massive increase in the number of private vehicles on its roads overwhelming the transport infrastructure. Shown here is a traffic jam in Delhi.

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  Rapid economic growth in China has resulted in a massive increase in the number of private vehicles in its major cities. Shown here is a traffic jam in downtown Haikou, Hainan Province, China.

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  This is an image of "African people at work" from

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  Costs of Congestion and Parking Search