Re: [NSW] Olympic Park/City Railway Signalling Question

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

FIRST STOP CENTRAL provides no further information but implies a low speed
indication.

In purely practical terms, if the book is correct, I can see nothing
inherently dangerous in this situation as there was always intermediate
train stops and the best visibility for sighting the rear of the train
ahead.  It would have helped no end in clearing a backlog of trains.

My recollection is (and I can't swear on a stack of Airport Line timetables
that this is correct) that an 8 car single deck set was delayed at Wynyard's
platform 6.  The following train closed right up to the last signal before
entering the platform ( literally several metres behind the 1st train).  The
1st train departed slowly and before clearing the station the 2nd train was
just starting to enter the platform.  As I wrote this is years ago, I was
watching both ends of the platform (beat going straight to school after the
tooth doctor), I just remember being amazed at what I thought I'd witnessed.

I thought Railway Quiz (1966 ed.) may help but it doesn't explicitly.  It
does state "In order to reduce the effect of station stops on the headway of
trains, intermediate train stops are provided at all City stations, with the
exception of Museum.  If the signal at the end of the station is at 'low
speed' indication, then the train must pass the four train stops at a
maximum of 17 m.p.h. for the first two train stops, 12 m.p.h. for the third
and 9 m.p.h. past the last stop, otherwise the train will be brought to a
stand before reaching the end of the station."  Again "the end of the
station" is ambiguous, I assume it means on entry to the station.

As for the authors observing this, if they did so reliably then some
provision is made for this operation.

The signalling system dated back to the 1920s with trains of poorer
performance especially in acceleration.

Chris

<signal_spotter@my-deja.com> wrote in message
>
> I have to question the integrity of this book when it comes to
> describing railway signalling matters. Anyway the signal
> leading into the platform could only clear (to a Low Speed) if the
> train was clearly past the following signal. And normally the track
> past that signal would have to be clear too but with about 3
> Intermediate trainstops this requirement could be reduced, in the name
> of headway. There would be no cases where a train could follow the tail
> end of another train into the platform.
> >
> > I also have a question.  What was the signal indication given?  If it
> was giving
> > a low speed indication (Red over Red over Green), and there was a
> train between
> > that signal and the next, it would be a signal irregularity.
>
> Agree it would be a signalling irregularity but to get a Low Speed on
> 825 signal requires all the tracks up to the next signal clear plus the
> overlap track (831AT) clear.
>
> >  The only possible
> > indication would be a calling on signal (Red over Red over CO), but
> the signals
> > before the platforms are all automatics, and Calling On signals must
> be fitted
> > to Home signals (and variations thereof).  Also, a Calling On signal
> is supposed
> > to have the trip up, which defeats the purpose of clearing it.  Does
> anyone know
> > the full details?
>
> I've checked how the SSI data was written (I have a copy) however it
> was written by RSA and the version may have changed from what I have to
> what is installed. Anyway the signals leading into the platforms will
> show a caution if the tracks a clear up to the next signal plus the
> next track past the next signal is clear. There is no Low speed or Call
> On on those signals, just a Low Speed on the home in the rear.
>
> regards Ian
> Signal Design Engineer
>
> >
> > --
> > 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.
> >
> >
>
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.