Australian signalling (was Crossing loop design)

["MattyQ" <matticue@corplink.com.au>]

In response to David Johnson's request, here is an overview of Australian
signalling. Victoria and NSW have been discussed with accuracy so I will not
include these. Also, I will only detail colour light Main (Running) signals
and not shunt or subsidiary signals.

Western Australia (Old system):-

The first colour light system introduced in WA was simply three aspect
(G/Y/R) signals on dolly's (brackets) similar to semaphore signals. Each
three aspect signal would apply to its respective line, decending from the
signal applying to the straight route eg

            R
             |  R                Straight route with two turnouts to the
right
             |_ |_R
                 |

                   R
                R |             Straight route with two turnouts to the left
            R_|_|
                 |

                R
            R_|_R            Straight route with one turnout to the left,
one to the right.
                 |

These signals varied according to requirements and (IIRC) only a few are
still in operation.

Western Australia (New system):-

G = Proceed
Y = Caution, next signal at stop
R = Stop

Turnouts are indicated by the use of Junction Route Indicators (JRI's) or
dot matrix route indicators.
JRI's consist of 5 lunar white lights at 45 or 90 degrees to the left or
right.
I do not know what is used to warn of a turnout indication in either system.
Maybe DW can comment.
Signal number plates mounted ON the mast denote an Absolute Stop (Home)
signal.
Signal number plates offset to the right of the mast denote a Permissive
Stop (Automatic) signal.

In Single Line Automatic sections, Home Arrival signals are of the 3 aspect
variety (G/Y/R) with offset 'C'and 'L' indicators. IIRC, if the main signal
is red and both the offset 'C' and 'L' lights are illuminated, the train may
proceed into the loop. The 'C' inidicates the loop is clear whilst the 'L'
indicates the loop points are correctly set. Can someone please confirm
this.

South Australia (former AN lines) :-
Almost identical to Victorian 3 position signalling so I won't go any
further.

South Australia (TransAdelaide) :-

G         = Proceed, normal speed.
Y          = Normal speed warning.
FY        = Reduce to medium speed (FY = Flashing yellow)
R          = Stop
G&JRI = Proceed medium speed (JRI indicates direction as in WA & Qld)
Y&JRI  = Medium speed warning.
Dot matrix indicators are use at Adelaide station on platform arrival and
departure signals.
Absolute Stop (Home) signals are identified by a white square 'A' plate
mounted ON the mast.
Permissive Stop (Automatic) signals are identified by a white round 'P'
plate offset to the right of the mast.

A curiousity of TransAdelaide signalling is that, since the illumination of
a JRI (in conjunction with G or Y)indicates medium speed, JRI's are use for
converging routes as well as diverging routes. Here is a typical aspect
sequence of a train passing through a loop on the Belair line :-

Second last auto        = Green
Last Auto                    = Flashing yellow
Home arrival               = Green & JRI to left (for example)
Home departure         = Green & JRI to right

Queensland :-

G        = Proceed
Y/Y     = Advance caution, next signal at yellow
Y        = Caution, next signal MAY be at red. (also used when preceding a
cleared turnout signal).
FY     = Special Caution. Line clear to next signal but obstruction exists
immediately beyond that signal
             (eg: rear of train in advance or trailing points set against
movement etc.). Max speed 40km/h.
             Depending on conditions, these signals may be approach cleared.
R/oY  = Proceed, Yard or Loop entry signal (oY = Offset yellow, offset in
direction of turnout). This signal bears
             the same authority as a FY. Where an oY applies to more than
one route, a route indicator (stencil or
             dot matrix) is used. These signals are usually approach
cleared.
R        = Stop
JRI's and dot matrix indicators are used to inform driver which road he will
be entering. JRI's can be at 45, 90 or 135 degrees from vertical to the left
or right as follows :-
1 turnout = JRI at 45deg (left or right)
2 turnouts = 2 JRI's, 45 & 90deg.
3 turnouts = 3 JRI's, 45, 90 & 135deg.
More than 3 turnouts in one direction = dot matrix indicator.

All Stop signals in QR are absolute, even if they are automatic.
In older installations, signals displaying a JRI will have a maximum yellow
indication only, irrespective of the indication of the signal in advance.
The preceding signal will be yellow.
In newer installations, the signal will initially clear to yellow with JRI.
When the train approaches the signal, it will step up to Y/Y or G if
conditions allow . The preceding signal will be yellow.

Three types of permissive signals are used which only display G, Y or FY.
These are identified thus :-
No number plate = Distant signal (at braking distance). Found in Staff and
Train Order territory.
Number plate with 'P' after signal number = Approach signal (at braking
distance). Found in CTC territory.
As above with separate yellow round 'P' plate = Repeat signal (NOT at
braking distance). Used to repeat signals with poor approach visibility.
Found anywhere.
Distant signals are indepentantly controlled whereas Approach and Repeat
signals are automatic and work in conjunction with the Stop signals to which
they apply.

Outside of the suburban area, Dynamic Speed Indicators (DSI's) are
progressively being introduced. These are a dot matrix display similar to
the types used for route indicators and are mounted on Approach signals in
CTC territory. They indicate the speed a train must be doing by the time it
passes the home arrival signal. The only speeds displayed are 25, 40, 50 or
80km/h. DSI's are mounted below the signal head whereas dot matrix route
indicators are mounted above the signal head. Indications of these Approach
signals are as follows :-
FY or Y = Home Arrival signal is at Stop.
Y & DSI indication = Home Arrival signal at Proceed for turnout.
G = Home Arrival signal at Proceed for straight route.

That's about all of it. Now, who was it who said QR signalling was simple?
Soon, I hope to do a web page devoted to QR signalling in its entirety. I
will post a bulletin when it is on line although it will be some months
away. Feel free to email me if anyone has questions.

Regards

Matt Smith
Brisbane, Queensland
matticue@corplink.com.au

You can't slam a revolving door.