Re: signals in sydney

[Eddie Oliver <eoliver@efs.mq.edu.au>]

WhaleOilBeefHooked wrote:

> Although sometimes (only ever seen them at country locations though) one of
> the bottom lights will be white, and will stay lit even when the top yellow
> is lit.

These signals are based on American dwarf position-lights (hence the
name) where no colours were used - only the configuration of the lights.
In its first installations, NSW used lunar whites and depended
predominantly on the angle of the lights (although a red was added, so
the choices were red + white horizontal for stop and two whites diagonal
for non-stop). 

This was then superseded by the full colourised versions, but a few of
the older ones hung on till quite recent times (e.g. Gosford). Are there
any still left?

A similar situation applied for single-light colour lights, which
originally had lunar white marker lights continuously illuminated - this
was replaced by a red marker light illuminated only with a red in the
top head (or if the top head failed). Also the "inclined band of light"
turnout indications on single-light colour lights were originally lunar
white, being progressively changed to the current yellows.

Eddie