This might prove to be a good building resource:
http://books.google.com/books?id=gIs5AAAAMAAJ&printsec=frontcover&dq=buildings+and+structures+of+american+railroads&hl=en&ei=0J0nTe6BGIWdlgfS27DfAQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCcQ6AEwAA#v=onepage&q&f=false