On 2 Jan, 23:58, "Clive D. W. Feather" wrote:
In message , Sir Benjamin Nunn

wrote:
Does anybody know why - given that both Jubilee Line platforms were of
completely new build, and one of the Northern Line platforms was
laterally resited - the interchange was not made more convenient and
accessible.
[...]
Couldn't they have put the Jubilee at a direct right angle to the
Northern Line, at a slightly lower level and with an equally generous
'island' between the platforms, then just had a bank of escalators from
platform level to platform level?

I have an axonmetric diagram (it says) of the station. From it, it
appears that the Jubilee crosses the Northern well south of the latter's
platforms. I presume there's a good reason it was sent that way rather
than under the Northern Line - perhaps to reduce the curvature and the
length of the line, since I believe the Northern Line station is roughly
under the main line bridge across Borough High Street.

Once you accept there were good reasons for putting the line that far
south, the interchange arrangements become pretty obvious.

Similarly at Waterloo, the main purpose of the Jubilee station was to
interchange with the suburban lines, not with the other Underground
lines. Hence the station was put at the right place to have an escalator
link to the Colonnades.

It must be very rare for tube platforms to be directly below each
other at interchanges. They nearly always cross somewhere beyond the
ends of the platforms, with the track height of the higher line below
the platform ceiling height of the lower line.*

The only exception I can think of might be the DLR at Bank.


*Which is presumably why the northbound Bakerloo at Piccadilly Circus
had to be extended over the crossover at the north end, because the
ceiling of the eastbound Piccadilly would have been where they'd have
needed to build the platform at the other end.