In message , at 20:04:45 on Sat, 10
Sep 2005, Mark Brader remarked:
According to CULG the present lifts travel 34.3 m (112'5"). That's
significantly deeper than Angel, which may be another reason why Covent
Garden was never selected for conversion. If the whole distance is to
be covered by a single long flight of escalators, their ends would be
offset horizontally by 60 m or almost 200 feet. If the lifts are at
one end of the platform, the escalators could lead to the other end,
but if they're in the middle, that wouldn't work.

Of course, if this was the only problem it would always be possible
to avoid it by using two successive flights of escalators at different
angles, like at Westminster. That has advantages and disadvantages.

There are escalators at Leicester Square - where the line will be
essentially the same depth under the surface. I don't remember the
layout, but presumably there's two flights with a circulating area
between, like at Holborn. That doesn't require the two sets of
escalators to be under one another [1], the unusual arrangement at
Westminster being because of the available footprint for the station I
guess.

[1] But if they were, and the escalators were split 50:50, you'd end up
underneath where you started.
--
Roland Perry