Ballast Types

[NW Modeling List]

Hello List, 

I’m looking through a reprint of the N&W Standards Drawings, specifically ballast sections.  The drawings show the ballast sections for tangents and curves (as well as single and double track) with “Class #1” ballast and a separate profile for “Class #2 or 3” ballast.

I’ll assume Class 1 is crushed rock; what is Class 2 and 3?  My guess is 3 is probably cinder and 2 is maybe gravel, but they're just that, guesses. 

Any idea?  Or should this go to the main list?

Matt