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Red means stop. Yellow means warning. Green means go. Blue means emergency. Aquamarine (right in the middle of blue+green) means engaged self-driving car? Do

Red means stop. Yellow means warning. Green means go. Blue means emergency. Aquamarine (right in the middle of blue+green) means engaged self-driving car? Do I really have to explain why red and yellow are compatable (warning/stop) and blue/green/aqua (emergency/go really fast/self driving car) is less so? Besides, my point was why not choose a distinct spectrum for unimportant information that has no chance of confusion? And really, what is the need for a “self driving color” as it’s not critical road information in the first place. It’s a “nice to know” not “need to know” piece of information. So, why any need for it at all? And if you’re going to do it, why such a poor choice of spectrum? There are plenty of other colors that have absolutely no risk of confusion.

codexb 3y ago
But red doesn't mean stop and yellow doesn't mean warning, when it comes to vehicle lights at least. They can mean emergency vehicle, a turning car, rear running lights, a braking car, non-police emergency vehicle, turn signalling, running lights, fog lights, etc. Red and yellow are used in lots of cases. In their passive use (not flashing), they're mainly used to distinguish cars and direction at night. There's a limited number of useful and distinguishable light colors for vehicles. There are even fewer useful colors for passive use during daylight. Blue-green probably makes the most sense for daytime, passive use.