Re: Signalling, was : Re: Outcomes of the Hines Hill crash.

Krel (krel4203@netconnect.com.au)
16 Jun 97 12:23:25 GMT

John McCallum <mccallum@melbpc.org.au> wrote in article
<5o4e0s$da8_001@melbpc.org.au>...
> In article <01bc7988$44b8b4c0$cad13fcb@krel4203.semex.net.au>,
> "Krel" <krel4203@netconnect.com.au> wrote:
> > We cannot even agree on what a Green over Red signal
> >indicates. States that use speed signalling like SA and Vic cannot agree
on
> >what Medium Speed is.
> >
> As far as I know, the Medium Speed indications in SA and Vic are the
same,
> i.e. yellow over green, except for the Adelaide suburban area, where the
> British system of a Flashing Yellow is used.
> However, Low Speed indications do differ in that SA allows a Clear Low
Speed
> whereas such an indication is very rare in Vic. Again the Adelaide
suburban
> area is different.

The difference is that in Victoria Medium Speed is 40 km/h and in South
Australia Medium Speed is 35 km/h.

Green over Yellow indicates "reduce to medium" which in Vic means pass the
next signal at or below medium speed except on the Western CTC (Pyrenees
Loop to Wolseley) where it means pass the Arrival Clearing Board at or
below medium speed. The Arrival Clearing Board is located at the beginning
of a speed proving section 200m or so before the home arrival signal. If
the speed reduction is proved the signal clears to a Medium Speed Warning
(more later), if not a run down begins that ensures (ha ha) that the train
is under control. Another case of Signal Engineers trying to drive trains.

Red over Yellow indicates Medium Speed Warning meaning proceed, not
exceeding medium speed, next signal is at stop.

Red over Green indicates Clear Medium Speed meaning proceed, not exceeding
medium speed, next signal has a proceed aspect (ie not at stop).

-- 
Cheers Krel


"Any sufficiently advanced technology is indistinguisable from magic" -
Clarke's Law