Why do traffic lights have three colors?
For grown-ups: the science
Traffic lights use red for stop, yellow for getting ready to stop, and green for going when the road is clear.
Traffic signals use standardized colors so road users can recognize instructions quickly. Red has long been associated with stopping, yellow provides a warning or transition, and green permits movement only when it is safe and lawful.
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Transcript
At the corner, a traffic light shines above the street. Why does it use three colors?
Red means stop. It tells drivers to keep their cars still.
Yellow means slow down and get ready to stop. It warns that the light will soon turn red.
Green means go when the road is clear. Drivers still look for people crossing first.
Three colors give drivers quick, clear directions. That helps streets work safely together.