When railways first started appearing in Australia in the mid 19th century, the various states
we know today were still separate colonies of the British Empire, and each colony chose
its own standards for construction and operations, with little or no thought for compatibility with neighbouring systems.
Even after federation in 1901, the states remained responsible for their own railway systems,
and to this day the character of railways varies hugely between each state,
with different standards, designs and styles of operation.
Travelling between them can offer just as much variety to a railfan as travelling internationally
– and this is part of what makes Australian railways so interesting.
The most well known aspect of this is the different track gauges, which have caused
interstate compatibility issues since the very early days and is still a big problem today.
But in this video I'm going to talk about something that doesn't get mentioned as much,
and that's the different signalling systems employed by each state.
The simple early signalling in most states was broadly inspired by British practices,
but as suburban networks started getting busier in the early 20th century, states started
adopting much more complex signalling systems, able to convey more information and allow more frequent trains.
Despite still being part of the British Empire, the states of Victoria and South Australia
adopted a heavily American inspired system, while New South Wales took British concepts
but made something far more complicated out of them.
Queensland took some direct British influence with their system in the Brisbane suburban area,
introducing a 'double yellow' aspect in 1963.
Now the fascinating thing here is that despite all these multi-light systems being introduced
after federation, there was seemingly no attempt to avoid conflicting signal aspects in different
states – so several states ended up with combinations of lights that have a totally
different meaning in other parts of the county.
This is still the case today, and I'm going to show you some of the conflicts that exist in a moment.
But first, it's worth noting that unlike on the road network where traffic signals have
to mean the same thing everywhere for obvious reasons, it's almost a non-issue on the railways
because these systems are all a long way from each other, and the vast majority of train drivers
would spend their entire career driving within a single state's system.
However there are certainly a small number of drivers who would experience two systems
with clashing aspects on a regular basis – for instance a driver based at Junee half way
between Melbourne and Sydney will work shifts in both directions, and must know both Victorian
and NSW signalling.
Some drivers would also move interstate and get a new job, having to learn to apply different
meanings to familiar looking signal aspects.
So let's look at some of these conflicts.
The first one is fairly well known, and probably the one with the most potential for disaster
if it was interpreted wrongly.
In Victoria and South Australia, Green over Red means 'Clear Normal Speed.'
That means you can travel at the maximum permitted line speed, and expect the next signal to
be showing a Clear aspect as well.
It's the least restrictive aspect on those systems, and is basically as 'Go' as you can get.
However up in NSW, Green over Red has an entirely different, and much more restrictive meaning.
It means 'Caution,' which tells you that the next signal is at Stop.
So applying the Victorian meaning to Green over Red in NSW would be a very bad idea indeed.
Next up is Green over Yellow, which in NSW is a 'Medium' aspect, meaning the signal after next is at Stop.
In Victoria Green over Yellow is a relatively uncommon aspect, but indicates 'Proceed' on
a Repeater Signal – to a driver this has the same meaning as Green over Red –
proceed at line speed, next signal is clear.
Then we have Yellow over Red - In Victoria and South Australia, Yellow over Red is
'Normal Speed Warning,' which means you can proceed at line speed for the moment, but the next signal is at Stop.
In NSW this aspect is 'Caution Turnout,' which means you are about to take a diverging route,
and the next signal after the diverge will be at Stop.
Next up is double yellow – and this is our first one with THREE separate meanings!
How exiting.
Double yellow in NSW is 'Medium Turnout' – basically it means you are taking a diverging route,
but can expect the next signal to be clear.
In Victoria, double yellow is a 'Warning' aspect being shown on a Repeater Signal.
The meaning is essentially the same as Yellow over Red, which is proceed at line speed,
but be prepared to stop at the next signal.
Now I finally get to mention Brisbane which also has a double yellow aspect –
if you're familiar with British signalling, this is a British double yellow -
it means the signal after next is at Stop.
Next up we have another triple-clash, and that is this single flashing yellow –
notable for being the only clash that doesn't involve Victoria!
A flashing Yellow in NSW is the single light version of a 'Medium' aspect, which means
the signal after next is at Stop.
It can also warn of a turnout signal ahead.
On the Adelaide suburban network, a flashing yellow warns that the next signal must be
passed at Medium Speed – essentially the same as the Victorian or South Australian
Yellow over Green 'Reduce to Medium' aspect.
Then up in Queensland, a flashing yellow means 'proceed at no more than 40km/h, next signal
at Stop' – much like a Medium Speed Warning down in Vic or SA.
So those are all the significant examples that I'm aware of, but there may be other cases.
Like I said before, the real world consequences of all this are actually very minimal, and
I'm not aware of these conflicts ever leading to any sort of accident, but it's certainly
an interesting story of ..I guess.. unsupervised parallel evolution.
I would be interested to hear from any drivers who have worked over multiple systems, or
have had to change between them, and if you used any strategies to remain situationally aware.
If you'd like to learn more about the Victorian and NSW signalling systems I've made detailed
explainer videos on both of them, which you can find in this playlist, along with some
other systems from around the world.
Thanks for watching!