When Southern Cross Station was built/renovated/unnecessarily renamed, someone made the wise decision to include provision for an extra two platforms: 15 and 16.
These are now being built as part of the (possibly otherwise ill-fated) Regional Rail Link project, and seem to be progressing nicely.
There’s a catch.
It’s the big glass wall. It can’t be (cheaply) moved. It’ll have to sit in the middle of the new platforms.
So what will they do? There will be doors in the glass to get through it. Which means if it’s raining, you’d better take an umbrella if you want to use platform 16.
They probably have little choice now. Maybe the planning ahead wasn’t quite so good after all.