wrote:
I went through there today; they've certainly been busy since I was last
there about a month ago. What is the new steel structure being built
over the Overground tracks North of where the Underground tracks cross
them? It's not a bridge crossing the tracks, it looks more like an upper
deck running on top of them, but it can't get any further South than it
does now, because the bridges carrying the high-level tracks are in the way.

If that's what they've just done in a four day closure then they've done
well. Can't be the easiest place to crane things into and out of.

I think it's the new concourse above the ELL tracks you see in the first
illustration in
http://www.crossrail.co.uk/route/stations/whitechapel/