"Roland Perry" wrote in message
...
In message , at 13:33:12 on Sun, 3 Jan
2010, David A Stocks remarked:
The OPs suggestion that the Jubilee Line should have built further north
in order to facilitate an interchange with the existing Northern would
probably have meant putting the Jubilee Line plaforms under the river.

Only if the two sets of platforms aren't allowed to overlap. Looking at
the surface maps, and drawing a line between Waterloo, Southwark, and
London Bridge, it does seem very likely that the Jubilee line platforms
are south of Southwark St.

The Wiki page for the JLE

http://en.wikipedia.org/wiki/Jubilee_Line_Extension

has a link to a satellite image showing ground settlement in Central London
thought to be due to the JLE. There is a large blob of red (denoting
settlement) along Southwark Street to the west of Borough High St, and
smaller blobs in the St Thomas St and Joiner St areas. It looks like the
route may have had to run between tower/office blocks in this area.

This would have been a bad interchange with the main line, and may well
have run into other problems because ISTR one of the reasons for building
a new southbound (rather than northbound) platform tunnel was that the new
tunnel had to be threaded around the foundations of both the current and
pre-1830 London Bridges, not to mention the old C&SLR tunnels to King
William Street station.

The C&SLR tunnels are above the Northern Line tunnels, so don't have to be
"threaded around". They also curve sharply just beyond the station
... although the C&SLR didn't have a station at London Bridge, but I know
what you mean

to cross the river west of the bridge, whereas the Northern Line goes to
the right.

The pre-1830 London Bridge was about 30m downstream of the current bridge,
so the Northern Line probably runs between the two sets of foundations. This
would make sense because I believe it was pre-1830 bridge foundations (which
had been there for about 600 years when the bridge was demolished) that were
considered to be a bigger problem than the either of the successor bridges.

It would also surprise me to find that the Northern Line platforms went
under the river, so that sets some kind of bound upon the southern end.
From the "liftshaft building" to the river bank is 400ft, so that's about
seven cars.
I can't find any plans/diagrams of the station online, but various pages on
subterranea britannica etc. agree with my memory of the station. The
passages from the bottom of the main escalator to the platforms didn't
change much when the station was enlarged and you could still see where the
bottom of the lift shaft was when I last went through. These pages

http://www.abandonedstations.org.uk/..._Street_5.html
http://www.abandonedstations.org.uk/RaggaJohn.html

have some particularly relevant detail.

D A Stocks