Re: Signalling in Victoria

[David Langley <del@ancc.com.au>]

Maurie Daly wrote:

> >>
> >>
> >>Ive often wondered why this siding needs all the signal protection ,when
> >>similar sidings along the rest of this  line , eg Inverleigh,Cressy  and
> >>Ararat dont appear to need / get any signal protection at all.
> >>Another bizzarre Victrak rule maybe?
> >>
> >Maurie the reason is that the siding is switch locked the others are
> >master key locked!!
> >Paul Johnston
>
> Fair enough , but why is master key locking any more safe than switch locking?
> Or does the presence of the master key in a ground frame  lock prevent an
> authority being issued for that section of track ?
>
> MD

Good comment. I don't think that either is safer than the other.

The switchlock in auto signalling territory requires various track sections to be
clear before it can be unlocked to admit a train to the main line. Conversely if
the points are left reversed and unlocked the signalling "fails safe" and further
train movements have to be made under failure conditions until the problem is
rectified. In this instance by the next train locking the points normal. Failure
orders require all trains to stop at any intermediate points and inspect them to
ensure that they are correctly set.

Here we do not have any signalling on the main line hence the use of repeaters
(really point indicators placed some distance out from the actual points) to
enable trains to come to a stand safely prior to passing over the points that are
perhaps not properly locked.

Master key locks (staff locks in the good old days) require the use of a master
key and you cannot leave the points unlocked unless you leave the master key
behind also. The master keys are accounted for and any train issued with one must
hand it in at the appointed station. The numbers of the keys are also recorded on
the train control graphs.

David Langley.