That little house is the interlocking tower and operators control room. It protects that section of the main and controls the bridge. On the system timetables it's known simply as "Draw" tower. And I got some pictures and a small list of detail parts that I used for you Steamtrains. They are all Cal-Scale parts; #2003 Elesco feed water heater, # wp-343 water pipes, and #190-392 antenna support stands.
Two ARR mountains are about to drop there train in Allentown and head for the roundhouse to be turned for there next run. It's very common to see them double headed on fast freights. They are Jack of all triads engines, received from the USRA during the great war, and are still favored by crews allover the system in present day 1945.
Here are the two mountains getting serviced after a westbound run across the Delaware River into PA.
After taking water, 833 creeps onto the turntable.
865 is on the ready track for a run back east to Bergen point.
This shot shows a stock one on the right and a modified one on the left. I feel that the feed water heater adds some heft to these locos.
This last shot shows the PRR compatible train phone system. It was added to all locos that run on PRR trackage, as mandated by our trackage rights agreement.