Re: [NSW] Granville question re signals

[signal_spotter@my-deja.com]

In article <ObGx5.20745$cr3.531501@ozemail.com.au>,
  "Chris Downs" <cvdowns@ozemail.com.au> wrote:
> I don't know whether or not clearance of this signal was being slowed
by the
> signaller but not once was R/R/g displayed and out of the 4 or so
trains I
> watched depart only once was G/R displayed.  All other times this
signal
> went straight from R/R to G/Y.
>
> Chris
>
> David Johnson <trainman@ozemail.com.au> wrote in message
> 39C6DE3D.31611F64@ozemail.com.au">news:39C6DE3D.31611F64@ozemail.com.au...
> > signal_spotter@my-deja.com wrote:
> >
> > > In article <itbw5.16813$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.
> >
> >
>
>
Possibly because the DR relay (the one that drives the top green) cuts
the low speed circuit. So by the time it's cut the LSp and then makes
up the contact to light the top green is the possible reason for the
delay. I'm only guessing here.

regards Ian
Signal Design Engineer


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