The iconic traffic light colours have a perfectly reasonable explanation.
The concept that red signifies stop and green means go extends beyond traffic light colours and red light cameras. We’ve been taught since childhood that red represents danger and green represents safety. But why were those specific colours picked for traffic signals to begin with? Why couldn’t they have been prettier colours, like magenta and turquoise, for something we have to stare at every day? You’re about to learn.
While you’re at it, here are some more interesting facts and explanations for other minor details you’ve always wondered about.
What is the significance of the colours?
It’s crucial to remember that before there were traffic lights for cars, there were train signals. Initially, train firms used red to indicate stop, white to indicate go, and green to indicate caution.
As you might expect, train conductors had some issues with the colour white meaning go—bright white could easily be confused for stars at night, leading train conductors to believe they were in the clear when they weren’t. Railway companies finally adopted the colour green as the go signal. Yellow became the norm for indicating when trains should proceed with caution since it is easily distinguished from the other hues. That has been the case ever since. On another note, if you’ve ever wondered why the road lines are yellow, here’s your answer.
When traffic lights were installed, it became common for them as well—except in Japan, where the signals are a completely different colour.
Why was red chosen as the stop colour?
Red has the longest wavelength, which means it is dispersed less than other hues as it travels through air molecules, allowing it to be seen from a greater distance. Consider how the light turns red as the sun sets as an example. The human eye is most sensitive to a yellow-green highlighter colour (thus the colour of high-visibility safety jackets), although it can perceive red from a distance.
Yellow’s wavelength is shorter than red’s but longer than green’s. This implies that red is visible from the greatest distance, yellow is visible in the middle, and green is visible from the shortest distance—a useful prior notice for the need to slow or stop. However, this could be a coincidence. The connotation of red with stop originated with train warning lights, and it’s unclear if this was picked based on wavelength, contrast against green nature, or the natural association of red with things like blood. It might be a mixture of all three!
Yellow, believe it or not, was formerly used to mean halt, at least in terms of signage. Some stop signs were yellow in the 1900s because it was difficult to see a red sign in a poorly lit location. Highly reflecting materials were eventually produced, and red stop signs were born. Because yellow is visible at all times of day, it is still used to paint school zones, some traffic signs, and school buses. Keep these safe driving ideas in mind the next time you see a yellow light.
Don’t get frustrated the next time you’re stuck at a traffic light; instead, follow these driving etiquette guidelines and remember that traffic lights have gone a long way.
Info source – Reader’s Digest