Re: Signaller causes SPAD

["B." <gunzel412@dingoblue.gunzel.net.au>]

<signal_spotter@my-deja.com> wrote in message
8qp3qo$8g6$1@nnrp1.deja.com">news:8qp3qo$8g6$1@nnrp1.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.

So this is to prevent the bobbing of the track immediantly in front of
an approaching train erroniously releasing the locking, right?  I
think I've seen this referred to as 2nd track release or something.

Also, iirc approach locking can also be released if the apporoach to
the signal for x sections clear as well (providing the
signaller/system has restored the 'lever'.

But do signals in plain line sections, which are operating
automatically (maybe with only emergency replacement) need the one
'route' to release before reclearing?  (Which I can't see you'd need).
There is usually however a stick function to prove that the trainstop
(& maybe relay or searchlight) actually operates for each train, at
least in Victoria anyway.

If there is no route locking to be released, then for plain line
sections, there is no inherent sequentual proving?

Also, if a controlled signal is fleeting, does the route need to
restore before the signal can reclear?  Again, same problem.

> 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.

There are also 11 SSI's in Victoria:

Flinders St B, Flinders St C, Clifton Hill, Epping, Caulfield,
Dandenong, Sth Kensington, Newport, Sunshine, Coburg & Epping.

Relax Ian, there's 3 Westraces too:

Sunbury, Heidelburg & Ringwood.

South Australia has SSI too at Adelaide Station.

--
B.
Email - gunzel412 at dingoblue dot net dot au
ICQ#  - 82329734
Phone - long, long, short, long.