Virginian use of 2-8-4 505-509

[nw-modeling-list at nwhs.org]

I have just begun HO modeling based upon the Virginian, and have 
purchased a couple of 2-8-4 Berkshire's.  I would prefer to make up 
historically correct trains with these if possible, therefore:

What was the major use of this locomotive on the Virginian, and upon 
which portion of the railroad?

What are any, or all of the other uses of this locomotive on the 
Virginian, and where?

J. Tucker