On Mar 2, 2:49*pm, Basil Jet wrote:
On 2011\03\01 22:55, Robin9 wrote:
Does anyone know why they have not taken it through Canonbury tunnel to
Finsbury Park? Lack of money or lack of understanding of London's public
transport requirement?

Neither - or, I suppose "lack of money".

It looks at though some work is being done to
facilitate trains through the tunnel again.

I wasn't aware it closed... it was singled when the overhead went in,
because there isn't room for double track with overhead.

Basil is right on this one.

Also, note that the ELL tracks are the south pair on the four-track
alignment between H&I and Dalston, while the Canonbury curve joins to
the northernmost track of the alignment.

So in order to run a regular ELL service to Finsbury Park, you'd need
to build a dive-under allowing trains to access the Canonbury tunnel
from the south (a flat junction forcing trains going towards Finsbury
Park to cross all four tracks, and trains going towards Dalston to
cross three, would destroy the NLR capacity and reliability
enhancements and so couldn't be considered), at a cost of hundreds of
millions of pounds.

ELL services would then be dependent on a single-lead connection to a
single-track line, itself linking into a massively busy mainline. Did
someone say "performance pollution"? Or you could spend even more
hundreds of millions of pounds on making the dive-under double-lead
and on widening the tunnel.

All this, to save three minutes going up the stairs and down the
escalator...?

--
John Band
john at johnband dot org
www.johnband.org