"MetroGnome" wrote in message
news:u1omc.10$a7.7@newsfe6-win...
Not true. The entire length of the station has the same geology - which
at
platform level means that it is wholly within the Woolwich and Reading
Beds
("mushy stuff"!), as are the running tunnels on either side for a
considerable distance.

Further to this, the following is taken from "Jubilee Line Extension - From
Concept to Completion", by Robert Mitchell:-

"Further consideration was given to how settlement and disruption during
construction could be minimized. The geology of the area consists of made
ground overlying terrace gravels, London Clay, and Woolwich and Reading Beds
followed hy the Thanet Sands. Given the substantial presence of silty and
cohesive ground at the station tunnel axis, it was originally planned to use
compressed air with its attendant health and safety issues. It was decided
to raise the track level through the station by about 5m, thereby reducing
ground pressures and enabling the escalators, ventilation shaft and escape
stairs to be housed in a deep cut-and-cover box. Ironically, while this
reduced the amount of mining required, it had the potential to increase the
settlement problem owing to the proximity to the surface. The track
alignment was therefore shifted horizontally towards Jamaica Road to
minimize the risk of settlement to properties."
[...]
"Construction of the station was by Aoki:Soletanche as part of contract
105, awarded in November 1993 for £69.6 million. The diaphragm wall station
box is approximately 50m square with panels around 30m deep. The main
problem encountered was the thickness and density of the Thanet Sands and a
dewatering system was installed to lower the groundwater below the
foundation level. The contract allowed for compensation grouting at the
discretion of the contractor and limits of distortion and settlement were
specified for particular structures, extensive instrumentation being
introduced to monitor movement."


Hope this is of interest.

"Roland Perry" wrote in message
...
I'm trying to compile a list of interesting things to go see on the
"tube" on a day trip. Engineering mainly, like the crossover at the end
of the Oxford St Bakerloo, the scale of Canary Wharf and the tunnel out
of Bank-DLR. What others can the team suggest?
--
Roland Perry

How about Farringdon ? The widened lines dive under the Metropolitan lines
to the Northwest and there is Snow Hill Tunnel entrance on the Southeast.
Also, apparently, there are frequent problems with Thameslink trains to keep
you amused.
--
Cheerz,
Baz

"Marratxi" wrote in message
...

How about Farringdon ? The widened lines dive under
the Metropolitan lines to the Northwest and there is
Snow Hill Tunnel entrance on the Southeast.
Also, apparently, there are frequent problems
with Thameslink trains to keep you amused.

Also you can watch the Thameslink trains put their pantographs up and down.

--
John Rowland - Spamtrapped
Transport Plans for the London Area, updated 2001
http://www.geocities.com/Athens/Acro...69/tpftla.html
A man's vehicle is a symbol of his manhood.
That's why my vehicle's the Piccadilly Line -
It's the size of a county and it comes every two and a half minutes

On Thu, 6 May 2004 at 11:01:05, MetroGnome
wrote:

(N.B. I'm snipping massively here!)

(and London Bridge has interesting
curved gates in the Jubilee - Northern interchange subway).

Do we know what these are for? Or were they just to keep the Great
British Public out before the line was open? They would certainly
provide no protection in the event of fire or flood.

# Finsbury Park and Arsenal - deep tube platforms that aren't that deep,
and are accessed from the street only by stairs (with, at Finsbury Park,
spiral staircases in the former lift shafts to the main line station
high above).

What happened to those lifts, and why are they no longer used? Going up
to the high-level platforms from the Tube is a serious pain if you like
climbing stairs as little as I do!

# Finsbury Park (southbound Piccadilly line), Highbury & Islington
(northbound WAGN), Euston (northbound Northern Line, City branch) -
tracks diverted in the 60s to give cross-platform interchange with the
new Victoria Line, with the old course just about visible at each end
of the diversions. (Similar tunnels also visible on the Northern Line
near Angel, London Bridge and Borough, albeit for somewhat different
reasons.)

And at Stockwell, didn't the Northern Line swap a track with the
Victoria Line to enable cross-platform interchanges?

# Greenwich - DLR tracks surfacing beneath the main line station building.

And at Lewisham they're tidily tucked underneath the main line station,
too.

I must explore some of these parts of the Beckton branch! I like the
big flyover where the Lewisham branch turns right going to Canary Wharf,
and also just past Poplar, where the Eastbound Beckton branch crosses
the Stratford branch.

Some "non-LUL/DLR" items might also be worth a look -

# Heathrow Central (Heathrow Express) - cavernous entrance shaft
containing lifts and escalators at the T2/T3 end, which only exists
because of a tunnel collapse during construction (the shaft had to be
sunk in order to "reclaim" the area where the collapse occurred).

I remember that happening - the collapse, I mean!

# The Kingsway Subway - both entrances to the former tram subway (one in
the middle of the road just north of Holborn station, the other on the
Embankment under Waterloo Bridge) can still be seen, as can the former
entrances to Holborn tram station (staircases, now covered with grills,
in the middle of the road outside Holborn LUL station). Ride through
the Strand Underpass (road tunnel built through part of the disused
subway in the mid 60s) on a northbound 521 bus during Mon-Fri peaks.

We drove through it on Wednesday night, but I didn't find it easy to
tell where was original tunnel, and where was new construction. There
are a variety of metal doors giving exit from the tunnel ("Why," asked
my husband, "are pedestrians forbidden, yet there's a footpath, and
cyclists forbidden, yet there's quite a wide potential cycle lane!"),
but not obvious to what, or where.
--
Annabel Smyth
http://www.amsmyth.demon.co.uk/index.html
Website updated 8 March 2004

This isn't something you can actually *see*, but years ago, my rather
well-off great-uncle and his wife lived in a large flat on the top floor
of a very grand block in Hyde Park Street. Which was lovely - but for
the fact that whenever a Central Line train went underneath, which it
frequently did, the entire flat vibrated!
--
Annabel Smyth
http://www.amsmyth.demon.co.uk/index.html
Website updated 8 March 2004

In message , John Rowland
writes
"Roland Perry" wrote in message
...

What others can the team suggest?

The silver-painted glass tubes used to stop big trains from going into
little tunnels, visible from the north end of Finchley Road station. There
is also a set near Barons Court, but I don't think they can be readily seen
from any station.

I'm sure if you look West from Barons Court platform, you will be able
to see them.

There is also a set just after Hounslow Central on the westbound Picc,
although I'm not sure the last time a big train tried to go that far
west.
--
Steve Fitzgerald has now left the building.
You will find him in London's Docklands, E16, UK
(please use the reply to address for email)

In message , Annabel Smyth
writes
# Finsbury Park and Arsenal - deep tube platforms that aren't that deep,
and are accessed from the street only by stairs (with, at Finsbury Park,
spiral staircases in the former lift shafts to the main line station
high above).

What happened to those lifts, and why are they no longer used?

Taken out a very long time ago, if the state of wear on the stair treads
is anything to go by. Perhaps they didn't have the required capacity
when the passengers from the Victoria line were added.
--
Roland Perry

"Annabel Smyth" wrote in message
...
On Thu, 6 May 2004 at 11:01:05, MetroGnome
wrote:

(and London Bridge has interesting curved gates
in the Jubilee - Northern interchange subway).

Do we know what these are for? Or were they just to
keep the Great British Public out before the line was open?

I suppose they allow one line to be open when the other isn't - which seems
fairly useful.

MetroGnome didn't say why the gates are interesting - one gate curves one
way and the other curves the other way. To grasp how bizarre that is you
have to see the gates shut, which they never are.

And at Stockwell, didn't the Northern Line swap a track with
the Victoria Line to enable cross-platform interchanges?

No, I don't think so.

# The Kingsway Subway

We drove through it on Wednesday night, but I
didn't find it easy to tell where was original tunnel,
and where was new construction.

The flat bits are original tunnel, the ramps are new construction.

--
John Rowland - Spamtrapped
Transport Plans for the London Area, updated 2001
http://www.geocities.com/Athens/Acro...69/tpftla.html
A man's vehicle is a symbol of his manhood.
That's why my vehicle's the Piccadilly Line -
It's the size of a county and it comes every two and a half minutes

On Fri, 7 May 2004 at 16:39:20, John Rowland
wrote:

# The Kingsway Subway

We drove through it on Wednesday night, but I
didn't find it easy to tell where was original tunnel,
and where was new construction.

The flat bits are original tunnel, the ramps are new construction.

Ah, thanks. I'll have to notice properly next month, when we go again!
--
Annabel Smyth
http://www.amsmyth.demon.co.uk/index.html
Website updated 8 March 2004

On Thu, 6 May 2004, John Rowland wrote:

"Marratxi" wrote in message
...

How about Farringdon?

Also you can watch the Thameslink trains put their pantographs up and down.

You can do this for the North London Line at Dalston, i think. Not that
the NLL is tube; a change is as good as a rest, though!

tom

--
information distribution, vox humana, deviation, handle, feed, l.g. **