A traffic congestion map is a graphical, realtime or near-realtime representation of traffic flow for some particular area. Data is typically collected via loop sensors embedded in the roadways, then processed by computer at a central facility and distributed as a map view to users.
Many web sites or news channels show these maps as a tool of traffic reporting to help commuters decide how to avoid congested areas. Sometimes they are displayed directly to motorists using electronic signs, such as those on the 2nd Ring Road in Beijing. Frequently these show conditions on highways, but local streets can also be shown.