On Dec 13, 6:36 pm, Tom Anderson wrote:
On Thu, 13 Dec 2007, Paul Scott wrote:
"Tom Anderson" wrote in message
th.li...
On Wed, 12 Dec 2007, Andy wrote:

On Dec 12, 6:21 pm, Tom Anderson wrote:
On Wed, 12 Dec 2007, Andy wrote:

and there would be no connection back onto the LUL system for major
servicing anyway.

The St. Mary's curve to the District / Hammersmith & City lines is due to
be taken out early next year and so the line will be 'on its own' with no
connections to NR or LUL for a long time.

Why is this link being removed? Are platforms being extended over it or
something?

Its only purpose is for ELL trains to get back to their main depot -
Neasden is it? Once the ELL is rebuilt for main line spec trains, they
will have no requirement to enter the LU system, indeed they are
probably out of gauge for length anyway. The power supply and signalling
systems at either side of the curve will be incompatible, so the track
connection would appear irrelevant and unnecessary.

I smell circular reasoning! Why can't the ELL going to use A stock?
Because St Mary's curve is being taken out. Why is St Mary's curve being
taken out? Because the ELL isn't going to use A stock!

If the curve was left in, and other provisions made for continuing to run
tube trains, the line could reopen soon and carry on running as before
until the extensions are ready, at which point it could go over to NR
operation. Yes, this would be more difficult and expensive than the
current plan, but it would also mean that an entire line didn't have to
close for three years!

Apart from having a fourth rail, what would need to be done to make the
line tube-friendly? I imagine NR signals would be fine, you'd just have to
train drivers to read those instead of LU signals (do they do this already
towards Richmond and Amersham?). What's the situation with platform
height?

Interestingly, the Always Touch Out website says that the
infrastructure works were planned to be completed by May 2009 with
test running from there on as some stock would be available. However,
there appears to be some 'funny' dates in the construction section of
the link. http://www.alwaystouchout.com/project/3. I've not been
able to find any other information about the timescale of the
infrastructure works. If this outline plan is correct, then I could
certainly see a much earlier reopening, providing that there are
enough Class 378s are available to run a service.

Another consideration with running A Stock on the route is how would
you deal with the interface between LUL and NR signalling on the St.
Mary's curve? The curve is only 450m junction to junction and the
standard National Rail overlap is 200 yards (185m). There are already
restrictions on the curve: only one train is allowed on the connection
at once due to clearance issues with a train going the otherway. You
would also need a trip cock tester on the curve or you would need to
install temporary tripcocks to allow the A-stock to run. On the other
shared lines, tripcocks are fitted to the signals and the NR trains
(Class 313 in all cases) are also fitted.

I also know that Always Touch Out says that the St. Mary's Curve will
be retained, but I think that this information has changed now.