Richard J. wrote:
Basil Jet wrote on 14
November 2009 14:37:48 ...
Richard J. wrote:
Basil Jet wrote on 13
November 2009 10:46:44 ...
Richard J. wrote:
Basil Jet wrote on 13
November 2009 03:21:14 ...

But if you take David's plan and extend the Edgware Road
terminators back to Hammersmith (i.e. Hamm - KX - Vic - Edg Road
- Hammersmith, running in both directions) then you have ...

... confusion! Since your "extension" is actually a reversal, you
effectively have (a) a Hammersmith - Edgware Road shuttle, (b)
Hammersmith - KX - Vic - Edgware Road in both directions. You now
have two services terminating at Edgware Road, which is what
David's plan was trying to avoid.

No, you would have 12-16 trains an hour reversing without waiting.
Ha ha, very funny. :-)

baffled

Oh, I thought it was a competition to find the most impracticable
alternative to LU's plan. But if you're serious ...

"Reversing without waiting" implies stepping back, otherwise you'd
have to wait for the driver to walk the length of the train. Stepping back
two different services at one station would be
seriously challenging, especially if you're trying to do it within a
normal dwell time, or in practice probably 1½ minutes. LU aren't
very successful with driver changes in mid-route, e.g. Acton Town.

If the Wimbleware and Circle services both run at 6 tph in each
direction, you'll have 18 reversers per hour at Edgware Road (6
Wimbleware, 6 Hammersmith to inner rail, and 6 outer rail to
Hammersmith), not "12-16".

You have misunderstood twice. I said ...

you have the same frequencies on every stretch of track as
LUL's plan here
http://www.tfl.gov.uk/assets/downloa...ce-Changes.pdf ,

.... and I said ...

The pink line would need a new name and would run from Barking
to Wimbledon via Edgware Road.

i.e. There would be no trains from Wimbledon terminating at Edgware Road. In
fact there would be no trains terminating at Edgware Road at all, just
reversers between Royal Oak and Bayswater.

The point is that the recovery time would not be at Edgware Road but
at Hammersmith, Wimbledon and Barking etc.

Yes, that's the problem! If you don't provide any recovery time at
Edgware Road, any delay in one direction will automatically disrupt
the other direction too, partly because a late arrival at Edgware
Road will become a late departure, but also because conflicting moves
at the crossovers at Edgware Road and at Praed Street Junction will
worsen the delays. In other words, the reliability of the Circle
Line will suffer from the same problems that occur today.

No - The Circle's problem is that the whole circle only has something like 3
minutes recovery time, so a ten minute delay would take three whole circuits
to catch up, even without missing slots at flat junctions. (Am I right in
thinking Circle trains have priority at flat junctions? If they don't, then
that would help a lot without changing any lines.)

Ensuring step-free changes at Edgware Road would probably become more
difficult too.

No-one would need to change at Edgware Road, unless services were disrupted.

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