Use of Floodlights at Interlocking Towers/Stations was almost universal on all roads in the north east. Their use was not confined to what we now refer to as 'the corrider."
Purpose was to allow Operators/Towermen to observe passing trains during the hours of darkness for defects: stuck brakes, dragging brake rigging, hot journal boxes/bearings and in general any condition that would endanger the continued movement of the train. Operators/Towermen were required by Operating Rule to observe passing trains for defects and rear-end crew members were alert to take a hand signal from this individual. No execptions to the train would result in a 'highball', while any other condition would make a 'stop signal' mandatory.
The loss of a caboose/cabin at the rear of a train did not eliminate the Operating Rule that requires employees at trackside to observe passing trains for defects. The correct protocal today would be to immediately communicate by radio to the passing train its condition past the tower. The transmission would typically sound like: "(train #ID) ok on ther east (west) side by (location)."