Ding Bat wrote:
On Sunday, August 6, 2017 at 4:29:45 PM UTC+5:30, Recliner wrote:
Ding Bat wrote:
On Thursday, August 3, 2017 at 2:06:46 PM UTC+5:30, wrote:

As an aside, how do trains on the ECML get south of the river, where's the
link to the current thameslink route?


Trains from the north either terminate at King's Cross or go to a through
station under St Pancras. To reach the latter, a tunnel was burrowed under
the canal to the north of St Pancras.

The two Canal Tunnels, actually, built over a decade ago.

They're unfortunately named. A canal tunnel used to be for waterborne vessels.
https://en.wikipedia.org/wiki/List_o...United_Kingdom

I agree, and it's also a rather ambiguous name: one that linked it to the
area might have been better (eg, St Pancras tunnels?).


I was referring to the one for north to south traffic;
obviously, there's another for the other direction.

Well, it might have been a double-track tunnel.

On Tuesday, August 8, 2017 at 12:53:09 PM UTC+5:30, Recliner wrote:
Ding Bat wrote:
On Sunday, August 6, 2017 at 4:29:45 PM UTC+5:30, Recliner wrote:
Ding Bat wrote:
On Thursday, August 3, 2017 at 2:06:46 PM UTC+5:30, wrote:

As an aside, how do trains on the ECML get south of the river, where's
the link to the current thameslink route?

Trains from the north either terminate at King's Cross or go to a through
station under St Pancras. To reach the latter, a tunnel was burrowed under
the canal to the north of St Pancras.

The two Canal Tunnels, actually, built over a decade ago.

They're unfortunately named. A canal tunnel used to be for waterborne
vessels.
https://en.wikipedia.org/wiki/List_o...United_Kingdom

I agree, and it's also a rather ambiguous name: one that linked it to the
area might have been better (eg, St Pancras tunnels?).

I was referring to the one for north to south traffic;
obviously, there's another for the other direction.

Well, it might have been a double-track tunnel.

Tunneling today is done with an automated mole having a circular cross section,
so a Paris style semi-circular tunnel for double-track is impracticable.
Where does London have multi-track tunnels? Snow Hill? The route of the
former Circle Line? FWIW, the Canal tunnels' portal is double-track.

On 2017\08\08 10:40, Ding Bat wrote:
Tunneling today is done with an automated mole having a circular cross section,
so a Paris style semi-circular tunnel for double-track is impracticable.
Where does London have multi-track tunnels?

There are numerous between Kings Cross and Potters Bar. I doubt they are
all cut-and-cover.

On Tue, 8 Aug 2017 10:49:50 +0100, Basil Jet
wrote:

On 2017\08\08 10:40, Ding Bat wrote:
Tunneling today is done with an automated mole having a circular cross section,
so a Paris style semi-circular tunnel for double-track is impracticable.
Where does London have multi-track tunnels?

There are numerous between Kings Cross and Potters Bar. I doubt they are
all cut-and-cover.

No, definitely not, but they weren't drilled using TBMs, either. Given
when they were built, I assume they were cut by hand.

On Tue, 8 Aug 2017 02:40:15 -0700 (PDT), Ding Bat
wrote:

On Tuesday, August 8, 2017 at 12:53:09 PM UTC+5:30, Recliner wrote:
Ding Bat wrote:
On Sunday, August 6, 2017 at 4:29:45 PM UTC+5:30, Recliner wrote:
Ding Bat wrote:
On Thursday, August 3, 2017 at 2:06:46 PM UTC+5:30, wrote:

As an aside, how do trains on the ECML get south of the river, where's
the link to the current thameslink route?

Trains from the north either terminate at King's Cross or go to a through
station under St Pancras. To reach the latter, a tunnel was burrowed under
the canal to the north of St Pancras.

The two Canal Tunnels, actually, built over a decade ago.

They're unfortunately named. A canal tunnel used to be for waterborne
vessels.
https://en.wikipedia.org/wiki/List_o...United_Kingdom

I agree, and it's also a rather ambiguous name: one that linked it to the
area might have been better (eg, St Pancras tunnels?).

I was referring to the one for north to south traffic;
obviously, there's another for the other direction.

Well, it might have been a double-track tunnel.

Tunneling today is done with an automated mole having a circular cross section,
so a Paris style semi-circular tunnel for double-track is impracticable.
Where does London have multi-track tunnels? Snow Hill? The route of the
former Circle Line? FWIW, the Canal tunnels' portal is double-track.

That's true of most Tube tunnel portals, as the initial shallow
section is cut and cover. The TBMs only do the deep tunneling.

All of the sub-surface LU line tunnels are cut and cover. That's not
just the Circle line, but the Met line to Finchley Road and the
District line tunnels in East London. The Piccadilly line tunnel to
Hatton Cross is also shallow cut and cover double track. All of the
old mainline railway tunnels are also cut and cover, and usually
double track. Even the Brunel ELL Thames tunnel, though obviously not
cut and cover, is double-track. I've not seen an analysis, but there
must be almost as much double track tunnel in central London as deep
bore single track tube tunnels.

On 2017\08\08 11:54, Recliner wrote:

That's true of most Tube tunnel portals, as the initial shallow
section is cut and cover. The TBMs only do the deep tunneling.

I've just looked at numerous tube portals in Bing Maps using the 45
degree view. The pair of round portals are clearly visible in most. I
have found none which clearly match your description.

Basil Jet wrote:
On 2017\08\08 11:54, Recliner wrote:

That's true of most Tube tunnel portals, as the initial shallow
section is cut and cover. The TBMs only do the deep tunneling.

I've just looked at numerous tube portals in Bing Maps using the 45
degree view. The pair of round portals are clearly visible in most. I
have found none which clearly match your description.

I don't think the round Tube tunnels are visible at either end of the
Jubilee line, nor the Bakerloo line, nor the western end of the Piccadilly
line; not sure of the eastern end, but I don't think so. The Central line
Stratford tunnel portals are separate, with Crossrail tracks in between,
while the (separate) western portals are buried under the Westfield
development and no longer visible. I'm not sure about the Northern line
northern portals, but the tube tunnels are visble at Morden.

The Victoria line and Drain are entirely underground, so no portals. The
DLR Bank tunnel round tube tunnels are visible, but I don't think the other
DLR tube tunnels are.

On 2017\08\08 22:02, Recliner wrote:
Basil Jet wrote:
On 2017\08\08 11:54, Recliner wrote:

That's true of most Tube tunnel portals, as the initial shallow
section is cut and cover. The TBMs only do the deep tunneling.

I've just looked at numerous tube portals in Bing Maps using the 45
degree view. The pair of round portals are clearly visible in most. I
have found none which clearly match your description.

I don't think the round Tube tunnels are visible at either end of the
Jubilee line,

Finchley Road - N/A shared with Met.
Canning Town - the lines are covered by a structure which I believe has
something to do with flood protection.

nor the Bakerloo line,

N/A straddling DC line

nor the western end of the Piccadilly line;

N/A shared with District

not sure of the eastern end,

Bounds Green, Southgate South and Southgate North all have twin portals
visible from the air. Southgate North is very visible from a footbridge
(IRL, not on the internet) which enables you to easily see that the
entrance is larger than the exit for air pressure reasons.

but I don't think so. The Central line
Stratford tunnel portals are separate, with Crossrail tracks in between,
while the (separate) western portals are buried under the Westfield
development and no longer visible. I'm not sure about the Northern line
northern portals,

Finchley - N/A because of depot access between passenger tracks
Golders Green - 3 tubes visible (sic)
Hendon Central - 2 tubes visible
Colindale - can't tell, but almost certainly has separate tubes visible
in the right light

but the tube tunnels are visible at Morden.

Visible from the platforms IIRC.

The Victoria line and Drain are entirely underground, so no portals. The
DLR Bank tunnel round tube tunnels are visible, but I don't think the other
DLR tube tunnels are.

On 2017\08\09 03:18, wrote:
On Wed, 9 Aug 2017 02:22:46 +0100, Basil Jet
wrote:


nor the western end of the Piccadilly line;

N/A shared with District
Where do District trains share a tunnel entrance with the Piccadilly ?

You're right, they don't... the Picc trains descend between the District
tracks west of West Kensington. I can't be sure from Bing what the
portal looks like.


visible from the air. Southgate North is very visible from a footbridge
(IRL, not on the internet) which enables you to easily see that the
entrance is larger than the exit for air pressure reasons.

Is that this location
http://www.geograph.org.uk/photo/1400129

Yes

The exit northbound is two different sizes in quick succession
http://www.geograph.org.uk/photo/1400129

I think the outer one is to create an impression of symmetry with the
entrance, which is the same size but extends inward with the larger
diameter. I'm not sure why symmetry would be important in a portal pair
though.

wrote:
On Wed, 9 Aug 2017 02:22:46 +0100, Basil Jet
wrote:


nor the western end of the Piccadilly line;

N/A shared with District
Where do District trains share a tunnel entrance with the Piccadilly ?
AFAIK they only share tracks occasionally between Hammersmith and
Acton town and the odd District non passenger working to Northfields.

The District and Picc lines share track from Acton Town through Ealing
Common station to Hanger Lane Junction. Once in a while, a District line
train gets sent, wrongly, towards North Ealing, and occasionally Piccadilly
line trains serve Ealing Broadway.

Years ago it used be a District route shared with the Piccadilly but
that stopped long before the line was extended to Heathrow

Originally it was purely a District line route all the way to Hounslow. The
Piccadilly line came later.