"asdf" wrote in message
...
On Sat, 31 Oct 2009 11:45:46 +0800, DW downunder wrote:

The current run-time is 16mins, according to earlier posts this thread.
Turnaround times are subject to standards for railway operation.

1) Use of what are effectively Light Rail vehicles (in the manner of Tyne
&
Wear Metro and DLR) allows other (ie non-railway, eg tramway) turnaround
parameters to apply;
2) While it has been commented that the Class 350 have tram-like
acceleration - the question is: at what cost? Vehicle depreciation and
electricity consumption in particular.

So use an old 313 or whatever, rather than ignoring the costs of a new
one-off bespoke vehicle with its own maintenance requirements. The
saving in electricity will only ever apply to a single vehicle, so it
will be unlikely to be large enough offset the capital and
administrative costs of the change.

The point I was making was that while a 350 might have the acceleration
required, it's a high depreciation cost unit - also happens to use a lot of
juice to achieve its performance parameters. Rolling stock shortages bedevil
peak operations throughout Britain. Tying up a 4-car 350/1 dual voltage
unit, or 350/2 AC unit on an hourly branch line duty when 24 minutes each
hour during autumn timetable (28 in other seasons) are spent idle does not
strike me as an efficient means of utilising resources. If the timetable is
maintained at hourly, indeed reversion to 313 or use of AC only variants
(these were IIRC 314, 315, 316 but not sure of their fate) would not go
astray. Another option, worthwile only if interfacing 10 or 20 minute
interval connections, would be to change to a 40-minute interval service,
clock face even/odd hours.


3) If the line is operated as "one-engine-in-steam" with no operational
access to the main line (means manually locking points at Watford Jn
[WFJ],
I suppose), then Light Rail standards for end loadings and vehicle
strength
can apply. This means the desired acceleration can be achieved with
lighter
vehicles and lower power bills - has some "green" credentials to boot!!~~!

And precludes the single best improvement that could happen to the
line (through-running to London).

If that was a winner, do you think the present plan would have surfaced? I
have a gut feeling that if a local campaign for through running was
activated and gained traction (as they say), the likely outcome would be a
service through to either or both Stratford and Clapham Junction - not
Euston. Comments on the loadings on the WLL might indeed support the latter.


4) If the start-to-start turnaround including recovery can be got under 15
mins, then a half-hourly schedule can be maintained.

With little hope of recovering from any delay. Not helpful for
mainline connections.

Sorry asdf, but did you not notice that I wrote: If the start-to-start
turnaround including recovery can be got under 15 mins, ....



7) extensions would of course be on County Councillors' minds, subject as
always to business case and expenditure priorities.

IMO the whole idea is completely pointless without street-running
extensions.

And such extensions would be on the agenda no doubt .... as funds can be
allocated.

I guess the primary issue needed to be addressed is this: could an increase
in service frequency increase net revenue sufficiently to recoup the costs
of installing an intermediate loop? Alternatively, could the benefit of
through services at non-clockface intervals (or 40-minute intervals)
increase net revenue sufficiently to recoup the cost of signalling the
connections at Watford Junction [WFJ] for passenger operations? It would
appear both of these have been subject to BCR calculation and have not
achieved the hurdle rate required.

It does seem to me that providing rollingstock for a shuttle operation that
is technically deemed "not a railway" for turnaround performance
requirements may prove a little tricky. Essentially either 1 unit with at
least capacity equivalent to 2 x 20m cars would be needed running every 15
mins, or 2 units with capacity equivalent of 1 x 20m car needed. If the
latter, then 2-unit operations could occur during busy traffic periods, and
single unit operation at other times. On top of these, traffic and
engineering spares would be needed - or we'll see Sunday sevice bustituted
so that the one unit can be serviced.

Like you, I have doubts about the administrative and ongoing costs
associated with an isolated, small operation - unless somehow they can tap
into other fleets and operators of compatible rolling stock.

DW downunder