Why traffic light chose red, yellow and green signals?

Red means "stop", green is "go", yellow — "hurry up and turn the damn green!" Why these colors? Why not blue, purple and brown, for example? I had the assumption that it has something to do with wavelengths, I decided to test his theory.
Red means "stop" green — “go”, yellow — “hurry up and turn the damn green!» Why these colors? Why not blue, purple and brown, for example?

the Answer to this question, as it turned out, was a bit confusing, but in a certain sense it still was. The first traffic lights appeared for drivers, not for drivers. They consisted of red and green screens lowered in front of the gas lantern that was quite dangerous in case of leakage.


Red came off the railway tracks

Red symbolizes danger in many cultures, which from a scientific point of view is explained as follows: it is a light wave is the longest among all the visible colors of the spectrum. This means that you will be able to see the signal with the largest possible distance. Thus, red means “stop” long before the advent of cars. Since then, he has replaced mechanical “wings”, rising and falling to signal if the coast is clear. So, with that understood, it is not so difficult.


Green primarily means "Caution!”

But the role of the green signals have changed over time. The wavelength of light, the green is shorter and follows immediately after a yellow in the visible spectrum. This means that it can be seen from a greater distance than any other color except red or yellow. During the first train of green traffic lights meant "Attention!”, and permission to go was given white. But to stop the train the engineer would require much more time than the driver of the car. And after a few major catastrophes with the collision of trains happened due to the fact that the driver mistook the bright light of the stars with the signal “the Road is empty”, in operation there are only two colors: red and green.

Yellow means “Attention”, because he is almost as well marked as the red

With the advent of the automobile until the mid 90-ies not all stop signals were red, some were yellow. So it was decided to make for the reason that at night in poorly lit areas, drivers were hard to see barely stands out because of the red filter light. For a long time only used yellow to indicate the need to stop. It started in Detroit in 1915 — the town, which 5 years later installed the first electric traffic light with “amber” color.


But what happened with the original value of the yellow signal? With the advent of electricity and new opportunities the need to use it as a stop sign instead of red, disappeared. Therefore, the color remained as a warning sign that we need to prepare.