Re: [NSW] Granville question re signals

["Chris Downs" <cvdowns@ozemail.com.au>]

I don't know whether or not clearance of this signal was being slowed by the
signaller but not once was R/R/g displayed and out of the 4 or so trains I
watched depart only once was G/R displayed.  All other times this signal
went straight from R/R to G/Y.

Chris

David Johnson <trainman@ozemail.com.au> wrote in message
39C6DE3D.31611F64@ozemail.com.au">news:39C6DE3D.31611F64@ozemail.com.au...
> signal_spotter@my-deja.com wrote:
>
> > In article <itbw5.16813$cr3.444008@ozemail.com.au>,
> >   "Chris Downs" <cvdowns@ozemail.com.au> wrote:
> > > I stood at the Sydney end of Granville's platforms 1 & 2 for  half an
> > hour
> > > last night.
> > >
> > > Watching OP yo-yos on the up main they were leaving Granville and
> > running
> > > express to Lidcombe.  Four up main signals are visible, Granville up
> > main
> > > starter (1), up main intermediate before Clyde (2), Clyde up main
> > starter
> > > (3) and the following up main signal (4) on the way to Auburn.
> > >
> > > When a train leaves Granville on no occassion did sig 1 clear before
> > sig 2.
> > > I assumed sig 1 was being hald at danger by the signaller but
> > continued
> > > observation suggested this wasn't necessarily the case.  Once the
> > train is
> > > well on its way to Auburn the aspects shown at 1=G/Y, 2=G/Y, 3=G/R &
> > 4=R/R.
> > > 1 & 2 show the same aspect due to the short distance between 3 & 4.
> > The
> > > part I don't understand however is that 2 when from G/Y to G/G several
> > > seconds before 1 went from G/Y to G/G every time.  The result was a
> > sequence
> > > of four signals showing G/Y, G/G, G/Y & G/R.
> > >
> > > Does anyone know why this is so?
> > >
> > > Ta
> > >
> > > Chris
> > >
> > >
> > Possibly due to the delay in processing. (1) signal would look at (2)
> > at G/G before stepping up to G/G in the logic.
> >
> > ie The SSI data for S1 aspect sequence would look as follows:-
> >
> > G s 73                 (R/R)
> > if S2 set <y           (test for S2 memory at 'better than G/R')
> > then G s 5             (drive top green lamp ie output 5)
> >      G c 7             (turn off top red lamp)
> >      if S2 set fyy     (test for S2 memory at G/Y)
> >      then G c 3        (turn off bottom red lamp)
> >           if S2 set g       (test for S2 memory at green)
> >           then S1 set g     (set S1 signal memory to green)
> >                G s 1        (drive bottom green lamp)
> >           else S1 set fyy   (set S1 memory to G/Y)
> >                G s 2        (turn on bottom yellow lamp)
> >           \
> >      else S1 set y          (set S1 memory to G/R)
> >      \
> > \
> >
> > Hope this helps.
>
> Okay, whay then, in Low speed areas does the Low speed light go off before
the
> top green comes on, exaggerated by the delay in proving the trip lowers?
At
> some locations, the low speed light goes off some 3 seconds before getting
a
> caution indication.   This scares the crap out of you when approaching a
home
> signal at 25 km/h and it goes back to stop.
>
> --
> David Johnson
> trainman@ozemail.com.au
> http://www.ozemail.com.au/~trainman/
> ------------------------------------
> These comments are made in a private
> capacity and do not represent the
> official view of State Rail.
> C.O.W.S. Page 11.
>
>