Hello Nj & Sheldon,
there is a conflict between your calculations;
What Sheldon has done, logically looks perfect, ‘each TCH requires 1/4 of ABIS TS’
So with this in mind, total # of Abis TSs = 51 is perfect.
While NJs formula is good and precise toOo, but it includes SDCCHs in the calculation hence requiring few more Abis TSs.
Also as I heard that one 4/4/4 site requires exactly 1 E1, so based on this, NJ’s formula looks fine.
PLease put some light on this both experts 🙂