On Mon, 01 Jan 2007 12:01:21 -0600, "Tristán White"
wrote:

As you will know, the line closes on 22 Dec 2007 until (at the earliest)
June 2010.

What I can't understand is why it needs to be down for so long. How long
was the Jubilee Line down during the JLE inauguration? Not that long, and
it seems to me that that is an even more complex scheme.

Two and a half years seems a long time to screw the good people of Wapping,
Rotherhithe, Surrey Quays and New Cross and stick them on rail replacement
buses. Could not the rest of the work be done while the ELL is running, and
then shut the ELL down for say just 8 months or so while they link it all
together? I mean, it seems such a long time for a line to be down.

AIUI the ELL is having its power supply, current rails and signalling
all changed to match National Rail standards. This is not a small or
quick job and would probably cost an awful lot more if attempted only in
engineering hours. There would also come a point where LU stock could
not run on third rail power supply so you'd end up with no service then
either. I don't know how much construction is going to be needed on the
current ELL itself to cope with the new standards but I imagine a fair
amount of supporting infrastructure will be needed.

The physical integration issue with other lines is different - the
northern section will be linked in on a section that is closed anyway so
no impact there. At the southern end I understand that a flyover is to
be constructed and I imagine there will not be a huge issue with linking
that in - a longish weekend possession could deal with that.

The bigger issues concern testing all of the signalling and control
systems and the new rolling stock and training the drivers on the larger
network. While there is a parallel here to the JLE it is important to
remember that the huge issues with the JLE arose when they joined the
new bit to the old bit. The interface at Green Park was (and to some
extent still is) a nightmare and caused huge delays and signalling
failures. Given the ability of the expanded ELL to spread delays all
over north and south London I imagine a lot of time and effort (probably
6 months if not longer) is going to be spent to try to ensure the new
line is reliable from day one. If not then TfL will be paying out a lot
of cash to FCC and Southern for delays to services between Central
London and Croydon.
--
Paul C


Admits to working for London Underground!