Bill Bolton <billbolton@acslink.net.au> wrote in article
<339ce88a.5889619@news.onaustralia.com.au>... > ajwright@ozemail.com.au (Ashley Wright) wrote: > > > I have a NSW signaling question. What does a signal that is RED on RED > > on Green mean???. I have never seen a signal like this before. > > That is a "calling on" indication. It means that the track ahead is > NOT clear to the next signal but that the train authorised to enter > the section on the basis that speed is kept low enough to stop clear > of any obstruction sighted. > > Automatic "calling on" indications are used in the "City Railway" area > to allow close headways. It is my understanding that most other > "calling on" indications are initiated manually by signallers or other > appropriately authorised safeworking staff. > > Cheers, > > Bill > > Bill Bolton billbolton@acslink.net.au > Sydney, Australia >
The way I remember it a calling on signal is a RED over RED over yellow. It
indicates that the points are set and locked for the intended move but the
track circuit is not proven. (ie there may be another train or vehicles in
the way or a broken rail.) The driver is authorised to proceed toward the
next signal but only as far as the line is SEEN TO BE CLEAR.
--
Cheers Krel
"Any sufficiently advanced technology is indistinguisable from magic" -
Clarke's Law