Traffic lights work in a set sequence, so even if you can't differentiate between the colours easily you (should) know the order for signalling.
When I joined the BBC it was mandatory to pass a colour blindness test, partly for electrical safety and partly for rigging circuits in dim lighting conditions. And I quote.....https://www.tradeskills4u.co.uk/posts/colour-blind-electrician
"Up until the 1970’s single phase electrical wires were coloured green, black and red. This was an issue since the most common form of colour blindness is where red and green are perceived as identical due a reduced sensitivity to red or green light.
As a result since the late 70’s the colour multi coloured (yellow and green) Earth was introduced, however it was only since 2004 that red was phased completely and brown now represents single phase line and blue represents the neutral."
When I joined the BBC it was mandatory to pass a colour blindness test, partly for electrical safety and partly for rigging circuits in dim lighting conditions. And I quote.....https://www.tradeskills4u.co.uk/posts/colour-blind-electrician
"Up until the 1970’s single phase electrical wires were coloured green, black and red. This was an issue since the most common form of colour blindness is where red and green are perceived as identical due a reduced sensitivity to red or green light.
As a result since the late 70’s the colour multi coloured (yellow and green) Earth was introduced, however it was only since 2004 that red was phased completely and brown now represents single phase line and blue represents the neutral."
