Instead of the standard red (stop), yellow (ready), and green (go), the Japanese have red (stop), yellow (ready), and blue (go) traffic lights.
The reason for the difference is the Japanese language.
In any language, words for different colours evolve over a period of time, e.g., the first recorded use of turquoise as a color name in English was in 1573.
And hundreds of years ago, the Japanese language also had only four colours: black, white, red, and blue.
Today, the Japanese word for green is midori (緑), but this word didn’t exist till the 8th century.
And even when it was introduced, it was thought to be a shade of ao (青), i.e., blue.
Even today, there are categories where green things are referred to as ao and not midori, e.g., leafy green vegetables (ao yasai) and green apples (ao ringo).
When the traffic lights were introduced in the 1930s, green was the colour for “go” but in the official documents and general conversation, it was referred to as ao (青).
This led to a bit of confusion, and rather than changing the official documents; the government decided to change the lights to the bluest shade of green possible.
Now, there is an international convention, the Vienna Convention on Road Signs and Signals, which standardises everything related to road signs and colours.
And all the member countries of this convention need to have traffic lights with red (stop), yellow (ready), and green (go).
But since Japan never signed this convention, it could continue using the blue shade instead of green.
