In Japanand in some countries of the world, it may happen to cross the road … with the blue traffic light! This apparently “bizarre” choice is linked to perception of colors: in the past, in fact, in those cultures there was no greennow called Midoribut this was considered only as one shade of blue, in Japanese ao. For this reason in Japan it is not so difficult to see traffic lights of a color different from the classic red, yellow and green.
The origin of the blue traffic light in Japan
To understand the origin of blue traffic light We must briefly see which words were used in the past to indicate the colors in ancient Japanese. In fact, at the time there were only:
- Shy (白) – White
- Kuro (黒) – Black
- Aka (赤) – Red
- Kiiro (黄) – Yellow
- Ao (青) – Blue
More specifically, with the term ao In reality, what we call green today was also considered. Later the Japanese language evolved and therefore today ao indicates only the blue, while the green is called Midori. The need to clearly separate these two colors came during the Second World War, when the need to paint military planes imposed a greater rigor in language to avoid misunderstandings. However, this ambiguity between the two colors still remains today, so much so that the government has pushed to choose the blue as a go -ahead signal on the traffic lights, unlike the greenery used in most of the other countries.
Is it legal to use a blue traffic light?
In 1968 many countries signed the Vienna agreement on road signsan international treaty whose goal was that of Stand the Stradal signalsthe. However, some states decided to get out, such as States United And Japan. From a legal point of view, therefore, the country of the Rising Sun would not have had any obligation to use green traffic lights.
But things changed in 1973when the country decided to adopt the green As a color for the crossing signal: among all the possible shades of green allowed by the Convention, they decided to choose that more tending to blue. In doing so they managed to make that signal more understandable, while not distorting it. At the same time we must keep in mind that the introduction of LED traffic lights has gradually flattened the difference between blue and greenallowing a large part of the population to gradually adapt to the chromatic gearbox.
