They're not the same gons getting moved around. They come in on NS 61N and go out as 60N loaded with steel slabs from Gloucester Terminal. For example, a 61N came in on
Thursday and another on
Friday.
Edited to add that the gons are stored on Westville siding because Pavonia has been full. Gons are often also stored on Camden's Controlled Siding and there's always a long cut of gons on a track at Pavonia.