I have a few each of boxes containing six pieces of Atlas curved N Gauge track.
Some of the boxes are marked
"Atlas 6-Sections 9 1/4" Radius Track #2510".
The others are marked
"Atlas 6-Sections 11" Radius Track #2520".
It looks like 3 sections of either the 9 1/4" Radius Track, or 3 sections of the 11" Radius Track form a quarter circle, but maybe not quite.
Does anyone know if these sections are made so that 12 sections is a complete circle?
If it matters, these tracks were bought probably in the early 1980's.
--- Joe