I stumbled upon this series of pages for testing colour blindness. It’s just an online version of those cards they use during eye tests. However, I don’t imagine that it’s as reliable as the optician’s cards, in the absence of any colour calibration of the monitor. I thought it was at least interesting and possibly useful, nonetheless.
I reassured myself that my colour vision is normal. Not a great surprise, since I’ve never had any problems.
Having said that, it is difficult to tell which traffic (and pedestrian crossing) light is on at any given time around here. Differentiating red and green is not the issue; the difficulty is in determining whether a lamp is illuminated in bright sunlight when it appears to have no more than a 20W bulb behind it and minimal cowling.
I prefer the simple expedient of looking for oncoming cars when crossing the road. It’s technically illegal to cross on the red man in Japan, I believe, but it hasn’t stopped me yet. Besides, looking out for my own safety is much more appealing that leaving it in the single spare hand of the driver chatting on his mobile phone and watching TV on his in car navigation system screen, even if the green man says I can cross.