WEB DESK: Meaning behind traffics light colours is essential to know and probably a very common thing for every citizen. Parents too told us when we were kids that red light means to 'stop' and green means 'go'. We learnt this by heart since then. 

But, you may find it different in Japan. And, it is linked to culture and it is being followed for hundred of years when the Japanese language has only four names for basic colours. black, white, red, and blue. Japanese describe green simply with blue. The colour green itself doesn't exist in Japan. For instance, the fruit vendor would sale you green coloured apple saying 'blue apples'. Also, they call blue "ao" in Japanese and green "midori". Since years, people of Japan are dealing with these colours like this and it seems like they are not going to accept green as green.

Earlier, traffic light was made green as it should be because international traffic law encourages every country to keep 'go' signal as green. But, the government of Japan had to compromise. But according to the writer of Atlas Obscura, Allan Richarz,"In 1973, the government mandated through a cabinet order that traffic lights use the bluest shade of green possible—still technically green, but noticeably blue enough to justifiably continue using the ao nomenclature."

Source: Reader's Digest