Color blindness, more common in men than women, takes many different forms and is present in a good 10%-15% of the population. With that in mind, you don't have to be able to see the usual red-yellow-green to know whether to stop, yield or go. Now, the redesigned red light will also show up as a triangle, the yield sign is still yellow and green for go will look like a square.
Listen: I'm all for replacing old traffic lights if it means I can get a couple to hang up in my rumpus room, but do you really think a triangle's gonna make that much of a difference to the colorblind? Haven't they already learned the light at the top is stop and the one in the middle is speed the f*** up then kiss your fingers and slap the roof?
Hit the jump for a comparison of the proposed new vs. old.
Re-learning The Traffic lights [yankodesign]
It's about time: redesigned traffic light includes the color blind [dvice]