This photo is reproduced from an envelope in which Pennsylvania mailed me the typically American Railroad Association booklets a railroad might send to a kid writing to ask about their trains. They didn’t understand that I wanted a timetable and photos, interior and exterior. The envelope was the best part of their response. Click to enlarge and click on the enlargement to enlarge further.
Is it two passenger trains passing, each with a fair amount of head-end, or is it a passenger and a freight? Since most Pennsy trains went through the curve in the dark, I might guess, using my 1954 Guide schedule, that one of these trains is the St. Louisan, the Duquesne, the Metropolitan, the Allegheny, or the Juniata. If both are passengers and are reasonably close to schedule, they would be the eastbound Allegheny and the westbound Duquesne.