Getting back to the OP:
I took the opportunity to look at some rail on a track paralleling the road I was stopping-n-going on for a while, remembering this thread. Interestingly, in different locations, the same railroad track looked to have slightly different hues, including greenish. Since it is winter, with nothing green in the vicinity to reflect that color, it must have been the rails, themselves. But, wait, there's more: in other places it looked dark brown, and in one place it seemed to have a slight purplish cast. The sky was an even overcast, so that should have made it look slightly bluish, but I did not seem to see that. The road and track were monotinously straight, so lighting angle was not changing.
The trouble with all of this color recognition is that it is somewhat subjective. The human mind attempts to compensate for the color of the illuminating light so that we tend to think "white" when viewing a panel we "know" is white, whether we see it in sunlight, incandescent light or flourescent light, which have bluish, yellowish and greenish spectrum shifts. And, on top of that, individual eyes may have slightly different color balance in their receiving cells. (Try looking at something in full-spectrum sunlight and alternately closing one eye, then the other - - some of us will see alternating slight shifts in color hue.)
Because most of us don't have sunlight illuminating our layouts, even going to the real object outside and matching it to paint swatches will not necessarily produce the same apparent color when we use the color for the matching swatch to paint our layout details.
So, I think we are really stuck with trying to figure out what looks right to us on our own layouts.
All I can say about that is, at least for me, I need to actually go out and look at the color(s) of what I want to model, rather than try to remember or assume a color based on generic "knowledge." And, even when it looks right to me, it may not look exactly right to others.
But, I do think I saw some "rail brown" looking color on some of those rails.