Why are traffic lights red, yellow, and green?

Why are traffic lights red, yellow, and green?

Why are traffic lights designed in three colors: red, yellow, and green?

There are two expressions for why red and green are used: the first is that in the 19th century, married women in Yorkshire, England wore more red, while unmarried people wore green. To show the difference, the design inspiration for traffic lights came from this.

The second statement is more scientific: this is because in visible light, red has the longest wavelength and can penetrate farther in foggy or dusty environments. Red is most suitable as a safety warning signal, while green symbolizes life and has some connection with traffic. At that time, red and green traffic signals were widely used in railway transportation.

How did the yellow light appear? At the beginning of the emergence of traffic lights, there were only two colors: red and green. According to records, the yellow light was invented by the Chinese man Hu Ruding. Hu Ruding was born in 1905 and went abroad to study at Cornell University and Massachusetts Institute of Technology in the United States. He was once a proud student of Edison. When I worked as an employee at General Electric Company in the United States, I was aware of the danger caused by the sudden change in traffic lights for pedestrians to cross the road. I came up with the idea of adding a yellow signal light as a connecting feature between the red and green lights, and it was adopted.