Can someone explain this?

[faraway]

Here is what I found in the GCOR about the placement of torpedo

3. Stopped on a Main Track
When a train stops on a main track, a flagman must immediately go back at least 1 mile, place
torpedoes on the rails, leave one lighted fusee, and may then return half the distance to the train.
Flagman must remain there until stopping a following train or until recalled.
(here is a figure with a distance of one mile)
If the flagman is recalled and safety will permit, the flagman must leave a lighted fusee and return
to the train. If recalled before reaching the prescribed distance, the flagman must place torpedoes
on the rails and leave a lighted fusee. While returning to the train, the flagman must also place
single lighted fusees at intervals shorter than the burning time of the fusee.
When the train departs, a crew member must leave one lighted fusee. In addition, until the train is
moving at least half the maximum authorized timetable speed for any train at that location, a crew
member must drop off single lighted fusees at intervals shorter than the burning time of the fusee.