1 gen 1920 anni - Automatic Traffic Light

Descrizione:

In 1920, William Potts developed several automatic traffic light systems, including the first three-color signal, which added a yellow "caution" light. Traffic lights (red, green and yellow) help people drive through intersections safely. They also help people walk across the streets safely. The lights allow people to take turns on the roads.

https://www.livescience.com/57231-who-invented-the-traffic-light.html

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