How the red and green lights has become now you know the color red, green, yellow light? One theory is that comes from the Chinese Hu Ruding. Hu Ruding early study in the United States at Cornell university, Massachusetts institute of technology in 1925 Edison chairman of general electric (ge) and the Massachusetts institute of technology (MIT) jointly organized a learning in class, is a student of Edison.

Hu Ruding ge company working hours in the United States, such as a green light at the crossroads once, when the green light to quickly open, and a speeding car, and his heart palpitations of thought of in the center of traffic light and a yellow light, the proposal also received the affirmation of the U.S. government and the support, yellow lights and introduce to the world.

But that is not very strong, because back in 1918, New York City has presented the top red, yellow, and green light -- - it is three color circle all around projector, installed in a New York City on 5th street, one of the towers. In 1920, the United States Detroit police officer William Potts also developed patent holders with a light yellow light of three colors, four direction. After multiple traffic lights to create patents have yellow light. But you can be sure that Hu Ruding did push forward the three color signals.