Why does Japan use blue traffic signals for go instead of green
While the rest of the world follows the standard green light, Japan’s "go" signals are famously blue—and it isn’t a mistake. Discover the ancient linguistic secret and the clever legal loophole that changed the country’s streets forever.
Too Long; Didn't Read
Japan uses blue-toned traffic lights because the Japanese language historically used the same word, ao, for both blue and green. To reconcile international safety standards with local linguistics, the government implemented a specific shade of cyan that is technically green but appears blue to the human eye.
The Turquoise Light: Why Does Japan Use Blue Traffic Signals for Go Instead of Green?
Imagine you are standing at a busy intersection in the heart of Shinjuku, Tokyo. As you wait for the pedestrian signal, you notice something striking: the light telling you to walk isn't the distinct emerald green you see in New York or London. Instead, it is a vibrant shade of turquoise, leaning heavily toward blue. This visual quirk is one of Japan’s most famous curiosities, leaving many travelers to wonder: Why does Japan use blue traffic signals for go instead of green?
The answer is not a simple matter of aesthetic preference or a manufacturing fluke. Instead, it is a fascinating intersection of ancient linguistics, mid-century bureaucracy, and international treaties. Understanding this phenomenon requires a deep dive into how the Japanese language perceives color and how that perception forced the hand of the Japanese government. This post explores the history and science behind Japan’s unique "blue" traffic lights.
The Linguistic Roots: The Concept of "Ao"
To understand the traffic light, one must first understand the Japanese word ao. In modern Japanese, ao (青) typically translates to "blue," while midori (緑) translates to "green." However, this distinction is relatively recent.
For centuries, the Japanese language used ao as a "grue" term—a linguistic category that encompasses both blue and green. Historically, Japan recognized only four primary colors: white, black, red, and blue. Anything in the green spectrum was categorized under the umbrella of ao. Even today, this linguistic legacy persists in several ways:
- Aoba: Literally "blue leaves," used to describe fresh, green spring foliage.
- Aoringo: Literally "blue apple," used to refer to green apples.
- Aojiru: Literally "blue juice," a popular vegetable drink made from green kale.
Because the word for "green" (midori) did not emerge as a distinct concept in common usage until the Heian period—and even then, it was considered a shade of ao—the cultural association between "go" and the color blue became deeply embedded.
1930: The First Traffic Signals
When the first traffic lights were installed in Japan in 1930, they were actually green. Official documents and the law referred to them as midori-shingo (green signals). However, the Japanese public instinctively referred to them as ao-shingo (blue signals).
As traffic lights became more common throughout the 1930s and 40s, the term ao-shingo became the standard vernacular. It felt more natural to the Japanese ear because ao traditionally represented the color of life, freshness, and "moving forward." Newspapers and radio broadcasts reinforced this terminology, and soon, an entire generation grew up calling the green light "blue."
The 1973 Compromise: Satisfying Law and Language
By the late 1960s, international standards for road safety were becoming more rigid. The 1968 Vienna Convention on Road Signs and Signals mandated that "go" signals must be green. While Japan did not sign the treaty, the government still felt pressured to align with international norms to ensure safety for foreign drivers and maintain consistency in manufacturing.
However, a problem remained: the Japanese legal code and the Japanese people were still using the word ao. If the government strictly enforced a "green" light, it would create a linguistic contradiction. In 1973, the Japanese government found a creative solution through a cabinet order.
The compromise involved two main changes:
- Linguistic Alignment: The official legal terminology was changed from midori (green) to ao (blue) to match what people were actually saying.
- The "Bluest" Green: The government mandated that traffic lights should use the bluest possible shade of green that still qualified as "green" under international lighting standards.
Modern Technology and Visual Perception
Today, Japan’s traffic signals are predominantly high-tech LEDs. To the naked eye, many of these lights appear distinctly turquoise or "aqua." According to research by the International Commission on Illumination (CIE), these lights sit on the very edge of the green spectrum, bordering on blue.
This unique hue serves several purposes:
- Cultural Preservation: It honors the linguistic history of the word ao.
- International Compliance: It remains technically "green" enough to pass international safety inspections.
- Accessibility: Some studies suggest that the specific shade of turquoise used in Japan is highly visible and provides better contrast for individuals with certain types of color vision deficiency (color blindness).
Conclusion
The "blue" traffic lights of Japan are a testament to the power of language over physical reality. While the rest of the world sees green, Japan’s history and culture demanded "blue," and the government eventually engineered a way to provide it without sacrificing safety. It is a rare example of a country modifying its infrastructure to fit its vocabulary, rather than the other way around.
The next time you find yourself at a Japanese crosswalk, take a moment to appreciate that turquoise glow. It isn't just a signal to walk; it is a living bridge between Japan’s ancient linguistic past and its high-tech present. Whether you call it green or blue, the message remains the same: it’s time to go.
