Editing Traffic (section)

===Speed limits===
{{main|Speed limit}}
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The higher the speed of a vehicle, the more difficult collision avoidance becomes and the greater the damage if a collision does occur. Therefore, many countries of the world [[speed limit|limit the maximum speed allowed]] on their roads. Vehicles are not supposed to be driven at speeds which are higher than the posted maximum.

To enforce speed limits, two approaches are generally employed. In the United States, it is common for the police to patrol the streets and use special equipment (typically a [[radar]] unit) to measure the speed of vehicles, and pull over any vehicle found to be in violation of the speed limit. In [[Brazil]], Colombia and some European countries, there are computerized speed-measuring devices spread throughout the city, which will automatically detect speeding drivers and take a photograph of the license plate (or number plate), which is later used for applying and mailing the ticket. Many jurisdictions in the U.S. use this technology as well.

A mechanism that was developed in Germany is the [[:de:Grüne_Welle|Grüne Welle]], or ''[[green wave]]'', which is an indicator that shows the optimal speed to travel for the synchronized green lights along that corridor. Driving faster or slower than the speed set by the behavior of the lights causes the driver to encounter many red lights. This discourages drivers from speeding or impeding the flow of traffic. See related [[traffic wave]] and Pedestrian Crossings, above.