Why isn’t traffic light purple? Unexpected fact about color choices

It would seem that what could be simpler than a traffic light? It stands alone at an intersection, flashes three colors and helps regulate traffic. But have you ever wondered, Why isn’t traffic light purple? Unexpected fact about color choices – let’s look at it.

Why did these three colors become the standard?

If you dig deeper, the choice of red, yellow and green is not at all accidental. These colors were originally used on railway signals, long before the advent of cars. Red is an obvious symbol of danger. Even in nature, it warns of danger. Think of bright red poisonous frogs or ripe berries, which can be toxic.

Green, on the contrary, is associated with peace and security. Logical? Undoubtedly. But yellow was chosen for a reason. It is the most visible color of all in the dark and in fog. Moreover, the human eye sees yellow almost as brightly as white, but without unpleasant glare. That is why it has become a signal of attention and expectation.

Interestingly, initially, green in railway signals meant “stop”, and white meant “go”. The problem was that if the white signal bulb burned out, it simply disappeared and the driver could perceive the absence of light as permission to move. Therefore, the meanings of the colors had to be redistributed. And since then green has meant “you can go”.

How do traffic lights differ in different countries?

Although the three primary colors remain the same almost everywhere, the details differ. In Japan, for example, instead of the usual green, a blue-green shade is used. The reason? For a long time, the Japanese language did not have a separate word for the color “green”, and it was considered a shade of blue. Therefore, the traffic light is officially green, but it looks more blue.

In Canada and some US states, horizontal traffic lights are found. Where red can be on the left or right, depending on the city. In Mexico and Argentina, arrows are sometimes added directly to the lights themselves so that drivers don’t get confused about which way to go.

And the Netherlands has “smart” traffic lights that change their signals based on the number of cars on the road. They can give the green light to cyclists during rush hour or even speed up the signal changes if they see that there is no one at the intersection.

The first traffic lights and railway signals

To understand the choice of colors, we need to go back to the time when the first traffic control mechanisms appeared not on roads, but on railways. By the end of the 19th century, trains were already moving at considerable speeds, and it was necessary to somehow signal the drivers when to stop or move on. It was then that color signals began to be used.

The first options were red (stop), white (move) and green (attention). But the system turned out to be dangerous: the lamps could burn out or accidentally give a false signal. For example, if the red glass broke, the signal turned white, and the driver could think that the path was clear. Because of this, the white color was removed, and green was given the meaning “go”. For the intermediate signal, yellow was taken – bright, noticeable. Which is clearly visible in fog and twilight.

The railway system turned out to be so efficient that when the first cars appeared, no one started inventing new colors. They simply adapted the already proven scheme.

How the human eye perceives colors

In addition to historical reasons, there is also a physiological explanation. Our eyes perceive light in a certain range of wavelengths. Red is the longest visible wavelength, so it is best seen from afar. Even in bad weather conditions. Yellow is almost as bright, but less aggressive. And green is one of the most calming colors for the human brain.

Interestingly, yellow-green is one of the most visible colors to the human eye at any time of day. That’s why life jackets and road signs are often made yellow or yellow-green – they’re simply impossible to miss.

Red is the color of danger.

Red has become a forbidden color for a reason. It is associated with danger not only culturally, but also subconsciously. In nature, there are many warning signs of red. For example, poisonous animals, fruits that can be toxic. In addition, this color causes emotional arousal and subconsciously makes us react faster.

Yellow is a symbol of attention and warning.

Yellow is a compromise between red and green. It attracts attention, but does not provoke as sharp a reaction as red. It is a kind of “get ready” signal, allowing drivers to quickly navigate the situation.

By the way, it is interesting that in some European countries (for example, Germany) the yellow signal is used not only before the red light turns on. But also before the green light turns on. This gives drivers an extra moment to prepare for the start.

Green is the color of safety.

Green is perceived as “permitted” not only for historical reasons. It is associated with nature, peace, the absence of threat. On a subconscious level, it is the most neutral and comfortable color. Therefore, it is ideal for the “go” signal.

This is how history, science, and physiology have come together to create a system that has worked for over a hundred years and is unlikely to change in the future.

Why didn’t they use other colors?

If the history of traffic lights had been different. Who knows, maybe today we would stop at purple, wait for blue, and move on white. But that didn’t happen. Why? What’s wrong with other colors?

Perception problems: purple, blue, white

Imagine that instead of the usual red signal, we would receive, for example, purple. Beautiful? Yes. Practical? No. The problem is that purple is poorly perceived by the human eye, especially in twilight and fog. Our eyes are simply not as sensitive to short-wavelength light.

Blue is a bit better, but it also has its own nuances. First, at night it blends in with the lighting of headlights and street lamps. Second, in many countries blue is traditionally associated with the police. If traffic lights were blue, it could create confusion.

As for white, it was originally used in railway signals, but was quickly abandoned. If the bulb burns out or the color filter disappears, the driver can perceive any white light as permission to move. Now imagine a night city where the glare of headlights, billboards and streetlights are solid white spots. The risk of error is enormous.

Cultural differences in the meaning of colors

Colors are perceived differently in different parts of the world. For example, in Western cultures, black often symbolizes death and mourning. While in some Asian countries, white has the same meaning. In China, red is the color of good luck, while in Europe it is a symbol of danger.

Green also has different meanings: in Muslim countries it is sacred, in some cultures it is associated with youth and life. But in general it is perceived positively. Which is why it was chosen for the signal “you can go”.

What if we went with orange or pink? Orange is already used for road warning signs. Pink doesn’t have a clear association, so it could confuse drivers.

Testing different options in the past

Traffic lights weren’t always the way they are today. There have been several attempts throughout history to change the color scheme. For example, some countries tried to add a fourth signal. Moving white light that meant the intersection was “under control” of an automatic system. But drivers confused it with street lights and abandoned the idea.

Another interesting experiment was conducted in the US. Some cities tried replacing red with dark purple to make the signals more contrasting. But it turned out that many people with visual impairments (for example, colorblind) had difficulty distinguishing it.

In short, the traffic light system went through dozens of trials before it became what we know it as. And it seems to work so well that it’s unlikely anyone will change it.

Evolution from mechanical to modern LED traffic lights

The first traffic light appeared in London in 1868. It had no electricity. But worked on gas lamps, which were switched manually by a policeman. What did it look like? A man in uniform stood near a metal pole and used levers to change the signals. But such a traffic light did not last long. Due to a gas leak, it exploded, injuring the operator.

After that, the idea of ​​traffic lights disappeared for almost half a century, until cars flooded the streets. In 1914, the first electric traffic light was installed in the United States. By the 1920s, it had the three colors we know today.

For a long time, traffic lights used incandescent bulbs with color filters. They were not very efficient. They overheated, burned out quickly, and in sunny weather the signals could appear dim. In the 1990s, the transition to LED bulbs began: they are brighter, consume less electricity, and last longer.

Complementary colors in modern systems

While the traditional three colors remain the main ones, some modern traffic lights are already testing additional signals. For example, scientists in the US are developing a white traffic light that will work for driverless cars.

How it works: If the drones receive a white signal, they decide who has the right of way, and drivers of regular cars simply follow. This should reduce congestion, as autonomous cars can make faster traffic decisions.

Some countries are also testing blue signals that warn pedestrians and cyclists that they have the right of way. For example, in Korea, traffic lights at pedestrian crossings may show an additional blue light when people have the right to cross the road.

Smart traffic lights of the future

The future of traffic lights is artificial intelligence and integration with transportation systems. Some cities are already testing “smart” traffic lights that change signals based on weather, time of day, and traffic.

In the Netherlands, traffic lights can detect the approach of an ambulance and automatically turn on the green light for it. In Singapore, a system is used that gives the elderly more time to cross – special sensors read their cards and continue the green signal if necessary.

And then? There are predictions that in the future traffic lights may disappear altogether . If all cars are driverless, they will be able to synchronize their movement with each other, bypassing each other at intersections without stopping. It sounds like fantasy. But even a hundred years ago, electric traffic lights also seemed unreal.

The most unusual color solutions (Japan, Iceland)

Traffic lights are not the same everywhere. For example, in Japan, a green signal looks… not quite green. Many Japanese traffic lights actually have a bluish tint , and this is no coincidence. The reason lies in the peculiarities of the Japanese language. In ancient times, the Japanese had one term for the colors blue and green (“ao”), and when it came time to introduce traffic lights, they argued for a long time about what to call the green signal. The result was a compromise that is officially called green, but has a bluish tint.

Even more interesting is Iceland. Due to frequent snowstorms, the standard red, yellow, and green colors can look washed out, so they tried using brighter shades. Neon yellow instead of yellow and light blue instead of green. Although such solutions did not become the standard, some traffic lights with non-standard shades can still be seen in some regions.

How the perception of traffic lights changes across generations

Interestingly, different generations perceive traffic lights differently. For older people, they are associated with strict rules and discipline. Because in the past, the streets were less chaotic and there were fewer cars. For millennials and Generation Z, traffic lights are not just a traffic control. But also… a source of entertainment.

There are many videos on social media showing “smart” traffic lights that play animations or have interactive elements. For example, in Germany, traffic lights have been installed where you can play ping-pong with random passersby on the other side of the road while waiting.

Traffic lights are one of those things that seem to be constant. Red, yellow, green—three colors that have guided traffic for over a century.

But the world is changing! Why do they stay the same?

• First, it is a time-tested system. Red is associated with danger, yellow is a warning, and green is perceived as a safe signal for movement.
• Secondly, the human eye best distinguishes these colors in different conditions – during the day, at night, in fog.
• Third, if something works, why change it?

This does not mean that traffic lights will remain like this forever. Additional signals for driverless cars are already being developed. Adaptive systems that adapt to traffic are being tested. Perhaps one day they will disappear altogether, and roads will become “smart”, controlling traffic without the need for traffic lights.

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