Re: Signalling in Victoria

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

MarkBau1 wrote:
> 
> Calling David Langely,
> 
> David, Could you dig up and post the circular that introduced 3 pos signalling?
> (my copy is still in Australia)

Please do, David, it would be very informative.

> It would be helpful to quote the bits where it specifically states that top
> arms are for mainline moves, bottom arms are for diverging routes, low speed
> for yard moves. (I can't recall the exact wording)
> 
> Eddie, this is not a "maybe" situation. As introduced the arms indicated
> mainline, diverging etc.

What if there was more than one diverging route? It is (at least in the
definitions I am acquainted with) NOT route signalling if more than one
route can be indicated by one particular display of arms or lights,
whereas a simple diverging/nondiverging dichotomy has much more the
character of speed signalling. I am not aware that (original)
three-position VR signalling ever attempted to distinguish amongst
multiple diverging routes? Or are you saying that every such three-pos
signal could only lead to precisely two routes?

We may indeed be dealing with disagreements in terminology rather than
disagreements in substance. You are arguing that VR three-pos evolved
from route to speed signalling, whereas I am arguing that it evolved
from one form of speed signalling (very route-oriented) into another
form (much less route-oriented). 

> Just like the system they copied. BTW, the US still
> uses 3 pos in its original form,

More details please? are you seeking to distinguish between roads which
have an indication like "approach diverging" from those who just use
"approach medium"? NORAC versus GCOR versus individual variants?

> only VR would take a perfectly good route
> signalling system and try to bastardise it into a speed signalling type system.

Then how do you consider all the American roads which do have the purest
speed signalling, e.g. who do not even mention "diverging" in their
aspects? Or are you saying that these never "started" as a route
signalling system and were therefore never bastardised from one? Would
the VR system have been acceptable to you as "unbastardised" if it had
happened originally in its current form rather than having evolved?

Eddie