Dogbert, the yard pictured on the diagram is Long Island City Passenger Yard and the one along Borden Ave was known as the Wheelspur yard.
This was before my time (1957) but fellow workers told how PRR trains were made up there and taken to Sunnyside for Penn crews to take over.
Those trains were the long distance trains bound for Florida, Chicago, etc.
This was discontinued in the late forties or early fifties. That period of time was during bankruptcy, PRR takeover and reorganization.
The track into Montauk Steel was actually a continuation of the switching lead from the Passenger Yard. Case Paper was also off this lead.
Bliss Yard was to the east on this diagram,in the lower right hand corner, across Dutch Kills Creek.