Bob,
I realize that the book wouldn't be dealing with tubular track but I'm interested in knowing how much of the book deals with things that would be useful across the spectrum of track (3 rail, 2 rail, scale, Gargraves etc.) Weathering, ballast, wood ties etc.
And, does the scope of the book go beyond "the outer edge of the ballast" to other details you might apply to create interest, such as piles of ties, signs, "junk" piles, weeds/ bushes, stuff like that?