Re: Three Position Signalling

["Notagunzel" <notagunzel@bigfoot.com>]

Exnarc <gwrly@netspace.net.au> wrote in message
7tla34$1edk$1@otis.netspace.net.au">news:7tla34$1edk$1@otis.netspace.net.au...

> Christopher_Martin GORDON <cmgord@ecr.mu.oz.au> wrote in message
> 7tjme0$fua$1@mulga.cs.mu.OZ.AU">news:7tjme0$fua$1@mulga.cs.mu.OZ.AU...

> > Newmarket:
> > Last year I went out to Newmarket to get a couple of photos of the
down
> > home (junction to Flemington Racecourse) This signal will show
normal
> speed
> > of a movement to Broadmeadows and a medium speed aspect of a
movement to
> > Flemington Racecourse.  During the time the Upfield trains were
running to
> > Newmarket and last year this signal showed red/green (clean medium
speed)
> > of the move to the Flemington racecourse line.  But for the exam
trains
> > in July and show trains in September this signal only showed
red/yellow
> > (medium speed warning) but the next 3 (2 position) autos were at
proceed.

> > Why did the signal only show red/yellow, when it should have been
> red/green
> > or is it that these times the showgrounds boxes were switched in,
were as
> > when the Upfield and empty car trains ran/run the Showgrounds
boxes are
> switched
> > out?

> Thats a good question, empty car movements to the Racecourse during
the day
> usually get a Bottom Green on that signal, but like you say the Show
and
> Exam Specials only received a Medium Speed Warning, whilst I can't
see why,
> it must have some bearing on whether the Showgrounds Signal Boxes
are
> switched in or out. The actual Newmarket panel is situated in
Kensington
> Signalbox and can be switched in or out by the Kensington Signalman,
of
> cause if it were switched out trains would not be able to access the
> Racecourse line anyway, so I assume the aspect is tied in with the
> Showgrounds frames???

Hmmmmm.......

If I was designing from scratch, you would only ever get a Bottom
Yellow.  AFAIK the aspects for any 'last' three position signal
leading into 2 position signals are that the 3P signal only displays a
'Clear' (Top or Bottom Green) aspect when a hypothetical distant
located at the same spot could display proceed; otherwise the 3P
signal should display a 'Warning' aspect only.

The other possibility is a circuit fault.  (Defective HR or suchlike).

Quite how the aspect could be tied up with the Showgrounds frame I
really don't know.

> How about one of the signalling expert filling us in on this one.

Definition of expert: Has-been drip under pressure.

--
Mr Notagunzel.
Rail Transportation Connoisseur.
notagunzel@bigfoot.com
(Waiting for any move at http://www.bigfoot.com/~notagunzel)