Re: [SA] White light on signals

["MattyQ" <mattyq1009@dingoblue.net.au>]

"B." <gunzel412@dingoblue.gunzel.net.au> wrote in message
3a66f037$0$15490$7f31c96c@news01.syd.optusnet.com.au">news:3a66f037$0$15490$7f31c96c@news01.syd.optusnet.com.au...
> iyb <iyb@dingoblue.net.au> wrote in message
> 3a66ecd7$0$15486$7f31c96c@news01.syd.optusnet.com.au">news:3a66ecd7$0$15486$7f31c96c@news01.syd.optusnet.com.au...
> > "Taliesin Walker" <taliesin@chariot.net.au> wrote in message
> > 3a66e8d7.3168211@news.chariot.net.au">news:3a66e8d7.3168211@news.chariot.net.au...
>
> >> This may be a silly question but:
>
> >> When travelling on trains in Adeliade I have noticed that
> >> some signals have row of write lights above and  running at a
> >> diagonal to the ordinary red, yellow and green lights. What
> >> information do these light convey?
>
> The application in SA, on Trans Adelaide to be precise is the line
> of lights, (sometimes called a JRI or 'feather')

also "Rabbit Ears" or "Lunar lights" (because the lamp colour is described
as "Lunar white" not "white").

is lit up when a
> train is to take a diverging route.  The driver is then supposed
> to slow down to the speed limit of the diverge through that
> particular turnout.  If the driver is not taking a diverging route
> then the JRI isn't lit.

Almost correct. TransAdelaide uses a somewhat bizarre mixture of British
"route signalling" indications but with US "speed signalling" applications.
The Adelaide suburban network used to have "speed signalling" as currently
used on ARTC, FA, Connex and M>Train tracks but TransAdelaide decided to
change to British style signalling indications. In a move, I can only
imagine was done for train crews, TransAdelaide retained the "speed
signalling" theory and applied it to the indications shown by the "route"
signals. This decision had a major impact on the design of the signals.

The presence of a JI (Junction Indicator or row of white lights) not only
indicates the route to be taken, it also qualifies the signal as being a
"medium speed" signal. This would be similar to an ARTC signal displaying a
red over green or red over yellow indication. Such is not the case in QLD or
WA where speed is governed by lineside speed boards, ATP and (in QR) Dynamic
Speed Indicators and the meaning of a JI only pertains to the route to be
taken (hence the term "route signalling").

Now comes the strange bit. Because "speed" signalling requires a medium
speed indication for CONVERGING routes (eg. where a loop or branch line
joins a main line), so too does the TransAdelaide system. As a result, a
signal governing such a junction will also be fitted with a JI even though
there may only be one path the train can take.

A good example of this is on the single tracked Belair branch. When a train
is required to use the Loop (or No.2 line), the Home Arrival signal will
show a proceed aspect and an illuminated JI. This indicates to the driver
that he must pass the signal at medium speed (as gazetted in the rule book)
and he will enter the Loop line. When the Home Departure signal clears, it
will also display proceed aspect and JI, even thought the train can only
rejoin the main line. The JI is required to indicate to the driver that he
must pass the signal at medium speed. In QLD and WA, such JI would not be
required.

Indications of TransAdelaide signals can be directly translated to ARTC or
Victorian indications:-

T/Adel                        ARTC
---------                        ---------
Red                           Red over red
Red with *shunt          Red over red over yellow
Yellow                       Yellow over red
Flashing yellow          Yellow over green
Yellow with JI             Red over yellow
Green                        Green over red
Green with JI              Red over green.

(*A shunt signal is two illuminated lunar white lights at 45°)


>
> > are used widely in other states too!!!

But, unlike TransAdelaide, JI's in these states have no bearing on speed.


--
Matt Smith
Brisbane, Australia

Email - mattyq1009 at dingoblue dot net dot au

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