Re: Signalling in Victoria

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

MarkBau1 wrote:
> 
> <<<<<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?>>>>>>
> 
> The overwhelming majority of US signalling is 100% route signalling. 

Mark, with the greatest respect, that statement is rubbish.

Perhaps while you have been working in the US, you have been working
only on GCOR roads. However if you had been working with similar
exclusiveness on NORAC roads (let alone CROR) you would probably be
saying "the overwhelming majority of US signalling is 100% speed
signalling". 

Since NORAC and GCOR have roughly equal areas of application, the most
you could say (even in your definition of what constitutes route
signalling) would be that 50% of US signalling is route signalling. 

For instance as I type, I have in front of me the Conrail Central Region
signal instruction document (for the part of Conrail derived from e.g.
the old Pennsylvania and New York Central), which is now effectively the
NORAC rules. There is not a single mention of anything to do with routes
in either the names of the aspects or the meanings thereof.

For instance red over green (GCOR "diverging clear") is Conrail (and
NORAC) "medium clear", defined as "Indication: Proceed. Medium speed
within interlocking limits". 

Of course we still have the definitional problem that you say that it is
route signalling because the GCOR signalling distinguishes "diverging"
from "non-diverging", whereas I say that it is route signalling only if
there is an explicit indication of WHICH route applies (not merely that
it is one of possibly several diverging routes). 

Moreover all US signal engineers and other signalling professionals that
I deal with consider even the GCOR as speed signalling, referring only
to some parts of Norfolk Southern (specifically, some parts of the old
Norfolk and Western) as the closest in the modern US to being
route-signalled. So I conclude that even they share the definition I'm
using rather than yours. 

Eddie