R/G colorblind here. I didn't realize how much I relied on traffic light order until I visited Houston, TX where the lights were horizontal. It was a very alarming experience.

In Michigan traffic lights are painted yellow, which works well for me at night. In California traffic lights are painted black, which means at night I cannot distinguish red and yellow lights. Although some traffic lights are now getting a reflective strip around the outside, which is the best.

It's briefly confusing if you have only lived in places with vertical traffic lights, and then move to someplace that has horizontal traffic lights, and vice versa.