This photo has a rail AND is a urinal: https://orhistory.com/archives/2524 . The article says it was in Oregon; I don't know if it was simultaneous invention or traveled from one continent to the other.
Seems more likely that's what the troughs are for and some people occasionally used them to relieve themselves.
I suppose America is more sophisticated, hence urinals needed to be referred to by the more genteel use for spitting.
Turns out, humans aren’t really designed to stand for long periods with feet flat on the floor. This contributes to stress on the spine, and you can feel it in your lower back. A foot rail allows us to redistribute the load on our feet—first one foot, then the other—and alter the tilt of our spines.
[side note : when not standing, I sit on a yoga ball and likewise move / shift often]