Basil Jet wrote on 15 November
2009 15:35:17 ...
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.

[At this point my previous post got careless, as you've pointed out. Sorry.]

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.

Yes, I know that, but reversing without a layover doesn't help - see my
comments above.

(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.)

Should an outer rail Circle train at Gloucester Road get priority over
an eastbound District? I would have thought the delay to the latter
would affect more passengers. Neither service appears to get priority
at that location at present.

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.

I assume you mean that people could change at another station and/or
wait for a through train. I suppose it's no worse that the current
situation.

--
Richard J.
(to email me, swap 'uk' and 'yon' in address)