Just adding on to the conversation and posing a question - if a new island platform is built, what will the platform numbers be? If they are 5 and 6, then the platforms will be numbered (west to east) 5, 6, 3, 4, 1, 2, which is crazy.I believe station platform numbers have changed in the past, where I cannot remember right now, but maybe someone else will know?
I know that they don't change platform numbers when new platforms in odd places are built (e.g. Lidcombe has platforms 0 - 5 rather than 1 - 6, and Homebush has platforms 2 - 7 instead of platforms 1 - 6), so they usually go backwards.
But here what will they do? There is no choice but to renumber everything (unless they're fine with 5, 6, 3, 4, 1, 2). This wouldn't have been so weird if the T4 platforms were platforms 1 and 2, in which case (though, this is still really weird anyway, but at least organised) the platforms would be arranged (again, from west to east) as -1, 0, 1, 2, 3, 4.
This part is a joke, but what if they numbered the new platforms 2.33 and 2.67 as they were between platforms 2 and 3. Or how about just rage-quitting and switching to platforms A, B, C, D, E, and F (obviously, no).
But seriously, I think the station would be renumbered, with the new T2 East Hills Line platforms and the T2 Airport Line platforms switching numbers (1 and 2 5 and 6)
And yes, I definitely think Tempe station is completely unnecessary. If it is "too expensive" (haha sure...) to demolish the station, then those platforms could be numbered 7, 8, 9 and 10 instead of 1, 2, 3 and 4. [Or, maybe this: -2, -3, -4, -5]