>>No, I believe usually there's one arrow for each direction, and it changes color...say, I guess we need a real color-blind person who knows all about this to weigh in and let us know the traffic safety issues :)
>
>Oh, that sounds really bad! Isn't the inability to distinguish between red and green common among people who are color-blind?

Yes, RG color-blindness is the most common...but then, in the research I pored over, as I said, it was noted that color-blind individuals become more adept at distinguishing shades of gray...thus they may determine the difference easily enough between a red light and a green light as different shades of gray...