One of the things I noticed in the anime Madoka Magica was that the traffic lights had a diffrent shape.

Red was an octagon. Yellow was a triangle. Green was a circle.

I had an uncle who was color blind, as in fully color blind. When I was a kid I asked him how he could drive not knowing if he should stop or not.

What he said to me was "Green is on top, yellow is in the middle, red is on bottom." It's such a simple answer that I was amazed I hadn't thought of it.