Traffic lights, or traffic signals, are located on most major corners in cities and towns
around the world. The red, yellow and green lights let us know when it is safe to drive through the intersection and when to walk across the street as well as when to stop and let other drivers, bikers and pedestrians take their turns to continue on their way.
The first traffic signal
Traffic jams were a problem even before the invention of the automobile. Horse-drawn carriages and pedestrians crowded the roads of London in the 1860s, according to the BBC. A British railway manager, John Peake Knight, suggested adapting a railroad method for controlling traffic.
Railroads used a semaphore system with small arms extending from a pole to indicate whether a train could pass or not. In Knight's adaptation, semaphores would signal "stop" and "go" during the day, and at night red and green lights would be used. Gas lamps would illuminate the sign at night. A police officer would be stationed next to the signals to operate them. https://www.livescience.com/57231-who-invented-the-traffic-light.html
