Re: Signalling queries

["Tony Gatt" <baulko@optushome.com.au>]

"Bradley Torr" <truenorth@one.net.au.SPAMTRAP> wrote in message
01c0f251$6cfd8280$c73e0c3d@default">news:01c0f251$6cfd8280$c73e0c3d@default...
> Hello all,
>
> Being only an interested layman when it comes to railway technology - my
> railfan interests mainly centre upon the generalities and the political,
> geographic and social aspects of railway systems - I don't know much about
> signalling, but I'd like to know more about it. To this end, I have several
> questions regarding signalling theory and practice.
>
> * What is the difference between 'train order working' and 'staff working'?
> I believe that staff working is centred around the idea of 'staffs', which
> I have heard being referred to as pegs or tokens, which are carried by
> train crews and then placed into a machine at certain points along a line
> in order to access the next section of the line.. am I correct?

Correct, Staff working is by posession of a physical staff (metal peg / token)
of which only one is available at any time (under correct operating
proceedures). Train Order working is a monitored system in which a train
controller issues an authority to move between points that he decides would be
best for the movement of the train.

>
> * What does "CTC" stand for, and what does it mean?

Centralised Traffic Control. It is the working of signals and safeworking
apparatus in a large are from a single point. (In Melbourne, The Standard Guage
from Melbourne to Albury was operated from a Control Panel in a Collins Street
Building.)

>
> * When a train enters a signalling section, the first set of wheels on a
> train make contact with track circuits, which alert the signalling system
> that the train is entering a new section. How does a signalling system know
> that the train has left the previous section, though?

The wheels create an electrical circuit (in a track circuited area) that
releases a relay (in easy terms). Whilst the circuits are bridged, the relays
will remain released. When the train leaves the previous section, the connection
between the rails no longer exists, therefore enrgising the relay and releasing
th track circuit.

There are also wheel counters (like in use at Rosehill.. counst wheels in, and
out)

>
> * I remember, during a journey in an Endeavour from Moss Vale to Macarthur
> in February 2000, seeing a sign somewhere around Picton on the Down saying
> something like "BEGIN SINGLE LIGHT INDICATION". I also notice that most
> signalling here in Wollongong is single light. At which points radiating
> from Sydney does double light signalling end and single light signalling
> begin?

Various areas, someone else will ahve to answer that one :)

>
> Thanks in advance for your kind and intelligent and constructive answers.
>

No probs. There are a couple of signal engineers in here that will gladly give U
all the information U need.
I only can explain the basics :)

> Regards
> BT
>
Tony.