I am curious to discover the origin of the NSWR single light turnout indicator, nicknamed the Scattered Aces. It was indicated by a slanted row of three subsidiary yellows positioned below the main signal head. The original single light turnout indicator being a large route indicator combined with a yellow main signal indication. The large route indicator was positioned above the main signal head, or for shunting and restricted speed, a small route indicator combined with a single subsidiary yellow indication.
I do recollect a circular for the implementation of the new single light turnout indicator for main line running, but, sadly cannot find that circular at home amongst my pile of safe working clutter.
The first application being combined with a yellow main signal indication. This reflected the Sydney Metrop colour light turnout indication given by top yellow. But, this was quickly altered to a red main signal indication after some misinterpretation incidents. Though utilized for main line turnout, such turnout speeds were normally slow, usually 25 kph.
A more recent alteration was the implementation of Medium indication by pulsating subsidiary yellows. Steady row of three yellows indicating the next signal is at stop, pulsating indicating the next signal is not at stop.
The Queensland Railway Junction Indicator (rabbit ears), being a slanted row of subsidiary lunar white lights may have been an influence. However, such rabbit ears were later adopted in NSW to act as a turnout repeater indication prior to the turnout signal. Or, did the NSWR signals branch adapt the Pennsylvanian Railroad Position Light signal type ?
In the photo, I am approaching signal D 90.2 Edgecombe UP home starter on the Down Main.http://s1098.photobucket.com/user/aussi ... sort=3&o=3
Having proceeded through the bi-directional running section between Zig Zag and Edgecombe, I will crossover to resume normal running on the UP Main. The main signal head is only capable of a red indication, as continuing in the wrong running direction is not possible under signals. Signal U 90.2 opposite is the Edgecombe UP Main home starter for normal running. The rear of signal 90.3 Down Home can be seen which also has a turnout indicator to permit crossover to the UP Main.
Steve.(Edited to correct link: SJ, moderator)