Railroads in Pittsburgh and McKeesport 1945-1955

I am trying to help my father research information on the steam locomotives in use around the Pittsburgh and McKeesport area from 1945 to 1955. Most use would have been coal hauling and steel mill locos. In particular, I would like information about the roads and the locomotives.
I have no idea and my dad remebers B&O and Union. He can’t recall the locomotive type though.

Any help would be greatly appreciated.