Re: Signaller causes SPAD

[signal_spotter@my-deja.com]

SSI data has inherent sequential proving of track circuits. It does it
by TISP data (Train In Section Proving) which has to be proved before
allowing approach locking to clear and the route to normalise. SSI is
in use throughout UK, Roma St and a few other junctions in QLD and the
major junctions in Sydney. I remember the circuitry we had to devise
for the Hawkesbury River to Cowan line which only has proving across 1
blockjoint (ie every second blockjoint). It proves the first track
occupied, the second track clear then the first track unoccupied. We
had to use magnetically latched relays to 'remember' each state. Much
more complex than SSI.

regards Ian
Signal Design Engineer

In article <39cb2e28$0$26537$7f31c96c@news01.syd.optusnet.com.au>,
  "B." <gunzel412@dingoblue.gunzel.net.au> wrote:
> David Johnson <trainman@ozemail.com.au> wrote in message
> 39CB1271.86E2738@ozemail.com.au">news:39CB1271.86E2738@ozemail.com.au...
> > signal_spotter@my-deja.com wrote:
>
> >> Apparently there was a near incident where a train nearly
> >> hit a loco. The reason was that the loco derailed and came
> >> completely off the tracks and therefore the track circuit
> >> picked back up. He was telling me that I should design
> >> into the system the ability to detect a train when it runs
> >> off the track.
>
> > It is possible with sequential clearing.  I think Cowan has
> > it, moreso not to lose trains due to sand on the track
> > rather than derailment.
>
> ISTR this has been discussed before.
>
> Sequential proving of tracks isn't common in Australia, but I seem to
> remember that QR uses some sequential logic in it's UTC software, so
if any
> irregular track circuit operation occurs, an alarm is generated for
the
> controller.
>
> There is also another NSW signalling installation (in the Hunter
Valley?)
> that has sequential operation of some sort.
>
> In Victoria the only thing that comes near it is the trap tracks at
tramway
> squares, as there isn't any track circuit through the H crossing
itself.
>
> Sequential operation of track circuits is used alot more in Europe,
where
> their signal relays don't use silver to graphite contacts.  So they
like
> proving absolutely all relay operation.
>
> --
> B.
>
> Email - gunzel412 at dingoblue dot net dot au
> ICQ#  - 82329734
> Phone - long, long, short, long.
>
>


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