Is this a magnetic sensor?

 
  Brenden Locomotive Driver

Location: Melbourne
Hi all,
I was just up from Lara near a rail/road crossing and notice at a signal gantry a set of beams in the middle of the BG tracks (both track). See below pic. Are these magnetic sensors for train positions sending signals to the adjacent relay box at the signal gantry?

cheers

Brenden


[gallery=http://gallery.railpage.com.au/modules.php?set_albumName=album51&id=IMG_7956&name=gallery&include=view_photo.php]

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  NR77 Chief Commissioner

There are 2 of them under the signals at Sunbury near a crossing as well. I think they are sensors that set off the crossing bells and gates.
  wongm GEEWONG

Location: Geelong, Victoria
It has the do with the TPWS (Train Protection Warning System) installed on all RFR lines.

The antenna transmits a RF signal, depending on the status of the signal, which is then detected by the train, and the systems on board the train decide whether to apply the brakes or not. It can be considered a more sophisticated version of the white train stops seen in the metro area.

This post has a good descriptions of what they do exactly:
http://www.railpage.com.au/f-p633557.htm#633557

And this report and presentation (both by Marcus Chadwick) give a great overview of the entire TPWS system in Victoria, abeit with a technical bent:
http://www.rtsa.com.au/chapters/vic/meetings/rtsa-tpws-pres-pt2.pdf
http://www.asiapacificrail.com.au/media/2006-irse-paper.pdf
  kuldalai Chief Commissioner

Two further queries with the RFR signalling :

1. Notice big black light boxes that are not normally illuminated but that display in white LED lights what appears to be an allowable speed to approaching trains. How are these triggered, do they show variable speeds  etc ? Why are they needed in addition to the normal speed signalling aspects ?

2. On the Ballarat line the lineside  lx  approach boards (some of) the black circle with the black cross within have the number 50 on the bottom RH corner. Surely this does not signify all trains must approach at 50 kmh ?
  Dreadnought Assistant Commissioner

Location: Oooh, look! [Pointing upwards] An eagle!!
In regard to Q2.

The LX signs with "50" on them are Predictor Boards.  The "50" is a reminder that the crossing has been set up for trains running over 50kph. Such trains may increase or continue to increase their speed up to the line limit.

Trains travelling at less than 50kph must not accelerate after passing the sign until they have cleared the approach and "island" track (the track through the crossing itself) or the predictor will not predict properly....

Cheers,
Dreadnought
  John of Melbourne The Ghost of George Stephenson

Location: Melbourne suburbs
1. Notice big black light boxes that are not normally illuminated but that display in white LED lights what appears to be an allowable speed to approaching trains. How are these triggered, do they show variable speeds  etc ? Why are they needed in addition to the normal speed signalling aspects ?
"kuldalai"

Existing signals (where applicable) have an illuminated "65" for "high-speed" crossovers.  I presume the things that you are talking about are for the new higher-speed crossovers for RFR.

The signalling merely indicates whether the train should proceed at normal speed (line speed) or medium speed (40 kph) for a diverging move through points.  So where the points will allow a higher speed, that higher speed is shown on the signal post.  It is illuminated whenever the diverging route is set through the points (perhaps subject to certain conditions).
  kuldalai Chief Commissioner

No these boxes show  in LED white lights  speeds of 130 and 160 and we don't have any turnouts / crossovers rated higher than 80kmh (and unfortunately too few of those). Good example is at Little River Up end facing trains about to enter East line section towards Werribee.  Also seen at Lara and Deer Park West . As said in previous post normally not illuminated only light up on approach of train . They are stand alone on the line side on gal poles and nowhere near the signals displaying Reduce to Medium or the Medium Speed aspects for diverging moves.
  EvanC Chief Plonker

Location: Bayswater, Victoria
Perhaps they're to signify temporary speed restrictions, for example due to wind/weather?
  vlinecars V/Man - "Yeah!"

Location: Here, there, everywhere!
Perhaps they're to signify temporary speed restrictions, for example due to wind/weather?
"EvanC"


They are active speed boards marking the end of a specifically marked high/lower speed section which state the highest authorised speed for the section ahead.
  wongm GEEWONG

Location: Geelong, Victoria
Existing signals (where applicable) have an illuminated "65" for "high-speed" crossovers.
"John of Melbourne"
and we don't have any turnouts / crossovers rated higher than 80kmh (and unfortunately too few of those)
"kuldalai"

It's pretty pathetic the lack of high speed turnouts. The Geelong line doesn't have any (only 65km/h sets) but they only get used for slower trains. On all the other lines, higher speed turnouts would let train into and out of loops much quicker.

They are active speed boards marking the end of a specifically marked high/lower speed section which state the highest authorised speed for the section ahead.
"vicrailpics"

I'm still a bit confused here. I think I need to draw a sketch of the Geelong line and mark where the speed signs are... Confused
  csyjunior Chief Commissioner

Perhaps they're to signify temporary speed restrictions, for example due to wind/weather?
"EvanC"


They are active speed boards marking the end of a specifically marked high/lower speed section which state the highest authorised speed for the section ahead.
"vicrailpics"

Theres one for up trains about 300m prior to Werribee St level crossing and i think for down trains a blue square speed board is provided which does the same job.
As for the high speed turn outs Sunbury and Pakenham have them that allow trains to change running lines at 80km/h.
You still get a reduce to medium  speed signal but a illuminated 80 is also displayed
  csyjunior Chief Commissioner

When the gallery is back on line i will post some pics of the items in  question
  csyjunior Chief Commissioner

No these boxes show  in LED white lights  speeds of 130 and 160 and we don't have any turnouts / crossovers rated higher than 80kmh (and unfortunately too few of those). Good example is at Little River Up end facing trains about to enter East line section towards Werribee.  Also seen at Lara and Deer Park West . As said in previous post normally not illuminated only light up on approach of train . They are stand alone on the line side on gal poles and nowhere near the signals displaying Reduce to Medium or the Medium Speed aspects for diverging moves.
"kuldalai"

This is what hes taking about.They are generally placed at the start and end of RFR territory and when changing from concrete to wooden sleepers
[gallery=http://gallery.railpage.com.au/modules.php?set_albumName=csyjunior&id=100_0269&name=gallery&include=view_photo.php]
These also do the same job

[gallery=http://gallery.railpage.com.au/modules.php?set_albumName=csyjunior&id=100_0267&name=gallery&include=view_photo.php]

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