If you are interested I have the chromatic values for B&O structures.  I've been drawing plans for a friend who is building an extremely large B&O layout, and who is considered an expert on the B&O.  As part of the design we came up with the values for the structure colors, for when I make the printed mockups.

Brown Trim RGB  40,36,0

Cream/Yellow Siding RGB 255,242,132

Roofs for smaller structures towers out buildings tarpaper/black (at least on the ones I've done so far).

I'm trying to to find the chromatic components R,G,B (red, green, blue) for Santa Fe structures, for a printed building project.  Does anyone know the RGB values for the yellow siding, green trim, and red roofs?