$4 billion rail tunnel back on track [The Age]. Moving the inner city half of the Glen Waverley line underground.

I almost dismissed it as a joke over six months ago and at the time they shelved the idea. Looks like someone is dusting it off.

I said:

Unfortunately, moving the line underground rules out any chance of extra lines to Glen Waverley. Something I'm sure will be needed soon. Of course we could always just rip down the new houses and businesses and build more trains on top. Ha.

I'd suggest building another couple of lines into the tunnel, and build them high enough to accept double decker trains while you're at it. Is it too expensive now?

I still say that.