I'm familiar with these terms (in other words I've heard them used a lot)
but have absolutely no idea of how they operate or what they mean. Could
anyone briefly explain the difference between them, and possibly, which
systems would be in effect where in South Australia?>>>>>>>>>
CTC is used to remotely operate crossing loops. Instead of having a signalman
at each station where trains meet the points at a CTC loop are electric motor
operated. A control operator (US term) sends electrical signals to the location
to tell the points what to do. He then operates the signals. The signals and
points are all interlocked meaning you can't clear a signal onto an occupied
track (some RR's have an overide on this to allow a low speed light) or a
signal on to a set of points that are not lying correctly for the move.
The other major function of CTC is that once a train enters a section between
two loops, no moves into the single line section are possible (the signals are
locked) from the other end. In the case of follow on movements in the same
direction, CTC allows this but only after the first train has passed a specific
signal.
In essence, instead of carrying a staff the signals that allow entrance into a
signal line section are your authority to enter.
In Victoria an identical system was/is also used called ATC. With CTC the
control operator is also the train controller. On ATC the control operator is a
signalman. On ATC the line is still directed by the train controller so
whenever a movement athority is given ATC rules have checks so that both guys
know whats going on.
Regarding ABS, I never worked with this system in Australia but I work with it
here in the US all the time. I will give the General Code definition but it may
not be correct for Oz.
(ABS) Automatic Block Signal System:
"A series of consecetive blocks (track sections) governed by block signals. The
signals are activated by a train or by certain conditions that affect the block
use" A certain condition for example may be a switch lock in use. Its important
to remember that at least in the US, ABS does not give you permission to be on
the track but rather controls your operation once you have permission to be
there, (by track warrant or whatever)
Regarding what is used in SA. I know that from Wolsely to Belair? it is CTC all
the way across that scenic wonder. I believe Dry Creek to Pt Pirie is CTC but a
local fan would know better than me.
Hope this helps
Mark.
THE ROCK is dead
Long live THE ROCK!