The line could be doubled from inside the tunnel through to Drayton Park (it looks as though it used to be!). It is only the curve at the NLL end which would have to stay single I think. But I am not sure on that. There are a lot of wires inside the tunnel at that end on the curve which I think must be something to do with gauging.
The line towards Finsbury Park is already called the up and down Canonbury as it is already reversible. Therefore up trains (towards NLL) could use this if the down slow 2 was made reversible between the Finsbury Park and the junction onto the Northern Heights line, with the disused platform next to platform 6 at Finsbury Park reopened. Down trains would go onto what is now the down Moorgate.
Trains from Highgate could alternate with trains from the GN going to Moorgate or the NLL.
The main parts of infrastructure required would be between Finsbury Park and Drayton Park, also reopening the disused platform at Finsbury Park. It would just need up trains from Highgate to run up Down slow 2 from the Northern Heights line junction through to the Drayton Park area

On Mon, 13 Aug 2007, somersetchris wrote:

Tom Anderson;65118 Wrote:

On Mon, 13 Aug 2007, Mr Thant wrote:

On Aug 12, 11:55 pm, somersetchris somersetchris.
wrote:

The only bottle neck will be Canonbury tunnel.

I meant the ECML diveunder south of Finsbury Park station, which I
don't think could be fixed to be double track very easily (I realise
there is a second track already, but it's pretty heavily used by
trains from Moorgate)

Given that there will still be a single-track bit through the tunnel,
how much difference does this really make?

The line could be doubled from inside the tunnel through to Drayton
Park (it looks as though it used to be!).

It did. But didn't someone suggest that it couldn't be redoubled while
also maintaining a freight-suitable loading gauge there? The curve is
quite an important link for freight, so that's rather important.

Perhaps it might be possible to arrange things so that one track is
cleared to W8 (or whatever) and the other only to W6A, signal the W8
reversibly, and just send all freight along that. It could even be
W8-and-only-when-nothing's-on-the-other-track, since it's not a very long
bit.

It is only the curve at the NLL end which would have to stay single I
think. But I am not sure on that.

Don't know. I'd assumed that was once double too, but i really have no
idea.

There are a lot of wires inside the tunnel at that end on the curve
which I think must be something to do with gauging. The line towards
Finsbury Park is already called the up and down Canonbury as it is
already reversible. Therefore up trains (towards NLL) could use this if
the down slow 2 was made reversible between the Finsbury Park and the
junction onto the Northern Heights line, with the disused platform next
to platform 6 at Finsbury Park reopened. Down trains would go onto what
is now the down Moorgate. Trains from Highgate could alternate with
trains from the GN going to Moorgate or the NLL.

Sounds about right. That kind of sharing of bits of line between two
services is asking for trouble, though.

The main parts of infrastructure required would be between Finsbury Park
and Drayton Park, also reopening the disused platform at Finsbury Park.
It would just need up trains from Highgate to run up Down slow 2 from
the Northern Heights line junction through to the Drayton Park area

You still have ELL trains crossing the entire NLL on the flat east of the
Canonbury junction.

tom

--
And the evening and the morning were the fifth day.

On 13 Aug, 16:56, Tom Anderson wrote:

It did. But didn't someone suggest that it couldn't be redoubled while
also maintaining a freight-suitable loading gauge there? The curve is
quite an important link for freight, so that's rather important.

Wasn't the reason for the singling to create enough height for
overhead line equipment, by moving the single remaining line to the
centre of the tunnel?

On Fri, 5 Oct 2007, wrote:

On 13 Aug, 16:56, Tom Anderson wrote:

It did. But didn't someone suggest that it couldn't be redoubled while
also maintaining a freight-suitable loading gauge there? The curve is
quite an important link for freight, so that's rather important.

Wasn't the reason for the singling to create enough height for overhead
line equipment, by moving the single remaining line to the centre of the
tunnel?

Yes, i think it was.

tom

--
Finals make a man mean; let's fusc up and write!