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.

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).

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.

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.