Hi All,
Don’t know if this has been posted before, but here goes…
Google scanned a book from 1893 titled: Buildings and Structures of American Railroads
While undoubtedly available in multiple places, I found it here (a Kiwi live steam club, no less):
http://www.wintercreek.net.nz/Downloads.aspx
It’s downloadable as a 27MB pdf of some 550 pages.
Enjoy,
Brian