On 17 May, 18:46, Roland Perry wrote:
I'd have thought it would be easier to drive one TBM through the site
(twice if two tunnels) before the box was there. Otherwise you have two
disconnected tunnels to bore, and a machine to move from one side of the
box to the other.

Quoth the horse:

"The plan is to have the SCL station platform tunnel primary lining
completed in advance of the arrival of the running tunnel TBMs. This
will allow the tunnel boring machinery to be slid through the
completed platform tunnels and re-start the running tunnel drive to
the next station."

http://billdocuments.crossrail.co.uk... 0Strategy.pdf

At Paddington (which is cut-and-cover, not SCL) they are planning to
build one of the running tunnels first, so that the earth from digging
the station box can be taken away to Royal Oak. At Isle of Dogs
there'll be no such shenanigans, as far as I know.

U