Re: [General] Information about block working

[Eddie Oliver <eoliver@efs.mq.edu.au>]

Ronald BESDANSKY wrote:

> I would seem, then, that I can accept a train from the box in the rear over
> the double line, if the platform road is unoccupied between the home and
> starting signals, even though there may be a train approaching on the single
> line (I wouldn't necessarily know if there was one approaching, if it was
> OTS worked. I would only know that there CAN'T be one approaching if I have
> the staff at my end).
 
That question has to be viewed in conjunction with the signalling on the
single line section. There would in such cases typically be an outer
home on the single line, as well as one immediately protecting the
junction. Instructions would typically exist (in the circumstances of
each individual location rather than as a generic rule) to prevent
immediately conflicting movements. 

For instance an instruction may exist that (in effect) if a train is
moving between the home and starting signals on the double line, a
simultaneous movement cannot be made inside the outer home on the single
line.

I don't believe that you could claim a completely general "rule" for
such situations. If you were modelling a specific place, you would want
to check the explicit rules as quoted in the Circular for that location.
But if you were modelling a generic location, nobody could challenge you
too much if you had your own local rules. Just avoid directly
conflicting movements with two trains moving into the face of one
another.

And there is still the issue of differences between different
jurisdictions. NSW tended to go for the "local instructions" approach
(and the clearing points for every location were explicitly identified
on its respective Clearing Point list, even if they were "standard"
choices). Many other parts of the world had a more generic approach. 

And I endorse Tezza's mention that the correct NSW term is "Block
Telegraph". If you say "manual block", people may put yet another
interpretation on it, e.g. block working imposed over a normally
automatic section by verbal communications, and/or sections where the
only block authority was verbal agreement between the signallers at
either end without the use of block instruments. 

Eddie