Re: Train Order working in NSW

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

Barry Campbell wrote:

> 
> What I want to know is
> 
> When does the NSW type machine indicate anything other than clear? Is it as
> soon as the the FPL starts to move or is it later?
> 
> What is the indicator meant to indicate under TO working? At present a
> driver can be assured that the points at an intermediate siding are locked
> as he (generally) has the key. At a staff station, the points are normally
> detected and the home signal cannot be pulled off without the points being
> set correctly and locked.

The indicator confirms that the points are set and locked for the main
route.

> What happens  when TO working is introduced? Is the ground frame simply set
> up so that it works independently of signals or tokens? If so, how? Is there
> a standard key used to unlock ground frames, presumably under the authority
> of a train order?

The arrangement is akin to the long-standing use of drivers' keys on the
Goobang - Broken Hill ordinary train staff and ticket working. The keys
are called "operator's keys" and are carried by train crews. They have
to be independent of signals and tokens because there aren't any signals
or tokens.
 
> Does anyone know?

If no one knew, there would be a serious problem.

You might note that in addition to (or instead of) the mechanical point
indicators, there are also colour light "main line indicators" (MLIs) at
some locations, which confirm the locking of all points on the main
route within the overall location (or at least up to the next MLI). MLIs
are also used for some other purposes, e.g. for level crossing
protection where there are some special needs for suppressing the level
crossing operation for shunting etc. MLIs are not signals but in many
respects serve signal-like functions; but they do not certify that the
track is clear.

Eddie