Different signals in Sydney area

 
  rgmccau Junior Train Controller

Location: Canberra
I went on the tour of the Sydney Goods lines yesterday and noticed some unusual signals, not only on the goods lines, but also on the general suburban network. In particular, the following:

and


2 single bulb (leds) lights, presumably multi-colour. These look more like Victorian signals than NSW! I'm not sure where the free-standing one is, but the gantry mounted one is near Strathfield.

-------------------------------------------------------



3 aspect signal head with top aspect blanked off - I don't know whether the middle aspect is green or (probably) yellow. This signal is just before a level crossing on the Botany line.

-------------------------------------------------------

Also some multi head lights had the lower head offset to one side, while others had them lined up. Is there any signalling reason or is it just luck of the draw or physical installation (clearance/sighting)?

I also noticed that there are considerable variations in the shape of backboards of "normal" signal heads - round, oval, square, round top-square bottom, no backboard at all - some examples in my flickr photos.



Any info appreciated.

Sponsored advertisement

  rgmccau Junior Train Controller

Location: Canberra
Not sure if the photo links worked, so here are the URLs.

single aspect heads - http://flic.kr/p/kaLTTi and http://flic.kr/p/kaLT78

2 aspect in 3 aspect head - http://flic.kr/p/kaLTzn

Photo set - http://flic.kr/s/aHsjSFzoCh
  awsgc24 Minister for Railways

Location: Sydney

2 aspect in 3 aspect head - http://flic.kr/p/kaLTzn

rgmccau


NSW has always liked having signals with the same sized background, even though some of the lenses in the lamp case are not used.

This practice is not quite as often nowadays, such as at Gordon (Starting signals for Up P1 and Down P2) and Roseville (Up Auto), but clearly signal BY1 at Botany has an unused space for a green lamp.

Occasionally the spare lamp case is brought into use, especially when a 3-aspect signal with no lower yellow is converted to a 4-aspect signal with a lower yellow.
  Junction box Chief Commissioner

Location: newy
How do the geen over green work with single lenses? Do they change color?
  Raichase Captain Rant!

Location: Sydney, NSW
How do the geen over green work with single lenses? Do they change color?
Junction box

As far as the Sydney examples go, "yes". They don't so much change colour as different LED's inside the signal light up as appropriate. So both of the examples pictured can show all of the signal indications as appropriate for the location, from full clear, preliminary medium, medium, caution and stop.

Additionally ST262 has a shunt indicator, most likely a calling on, which will illuminate when required.
  HeadShunt Chief Train Controller

Also some multi head lights had the lower head offset to one side, while others had them lined up. Is there any signalling reason or is it just luck of the draw or physical installation (clearance/sighting)?


Lower head offset to the right designates an automatic signal. Derived from American practice.
Where space does not permit the lower head of an automatic signal to be offset, a plate with the letter 'A' will be attached to the post beneath. 'A' plates are also often seen where controlled signals are converted to automatic but no adjustment to the signal head has been made.


3 aspect signal head with top aspect blanked off - I don't know whether the middle aspect is green or (probably) yellow. This signal is just before a level crossing on the Botany line.

NSW has always liked having signals with the same sized background, even though some of the lenses in the lamp case are not used.

Not a good practice, in my opinion.

I recall a 2 aspect automatic signal that showed only R and G but had a three lamp signal head with the centre light blanked out. A G/Y distant was provided in rear.
Following a certain fatal rear end collision between a DDIC and steam hauled heritage train, the arrangement was quietly altered to true 3 aspect, possibly because if the driver of the DDIC had seen a 3 aspect automatic signal go from R directly to G instead of Y he might have become suspicious and proceeded with caution.
Of course, it was not the fault of the unused centre light, but questions were asked, it was asserted that "everyone knew" it was only 2 aspect; it was labelled a "sneaky" setup.

Additionally ST262 has a shunt indicator, most likely a calling on, which will illuminate when required.

As far as I know, the subsidiary yellow on ST262 is controlled by the 'A' track circuit and therefore does not function in exactly the same manner as a conventional calling on signal. It is used for various shunting movements at the western end of Homebush, e.g. from Up Suburban to the Up Main, into platform 4 or to the Down Suburban and, in conjunction with a ground signal on the Down Suburban, for movements to platforms 3, 5, 6 and 7.
  Raichase Captain Rant!

Location: Sydney, NSW
As far as I know, the subsidiary yellow on ST262 is controlled by the 'A' track circuit and therefore does not function in exactly the same manner as a conventional calling on signal. It is used for various shunting movements at the western end of Homebush, e.g. from Up Suburban to the Up Main, into platform 4 or to the Down Suburban and, in conjunction with a ground signal on the Down Suburban, for movements to platforms 3, 5, 6 and 7.
HeadShunt

I'm not understanding your meaning? If it's a subsidiary yellow light, surely it is controlled by a signaller to permit shunting moves? The only subsidiary lights controlled by track circuits alone are low speeds.
  seb2351 Chief Commissioner

Location: Sydney
I'm not understanding your meaning? If it's a subsidiary yellow light, surely it is controlled by a signaller to permit shunting moves? The only subsidiary lights controlled by track circuits alone are low speeds.
Raichase

The signaller sets up the calling onon his board and leaves it to run down mode, meaning it is activated on approach circuity. Once the timer has run down after being activated by loco- similar to the low speed, then the calling on will illuminate.

Still controlled by the signaller, as they have to set it up. Another example I can think of is Dunmore to enter the Boral siding. There is a run down timer here as well. Similar but not the same set-up.
The signaller can also manually give you the calling on from memory in this situation/location as well.

The idea with these timers is that you don't hold up other equipment like level crossings for an excessive period of time. The signaller is then free to go and attend to other duties.
  Raichase Captain Rant!

Location: Sydney, NSW
Thanks seb2351, that makes sense. I was under the impression that the original post was implying that they were solely controlled by track circuits, which is impossible. They're effectively approach clearing then, holding the signal at stop until certain conditions are met, although the route itself has already been set and points set accordingly. Thanks again for clarifying.
  HeadShunt Chief Train Controller

I'm not understanding your meaning? If it's a subsidiary yellow light, surely it is controlled by a signaller to permit shunting moves? The only subsidiary lights controlled by track circuits alone are low speeds.
Raichase


Most subsidiary shunting signals are controlled by the 'A' track circuit, which means they cannot be cleared by the signaller unless the 'A' track circuit is clear, although in route control systems the route may be called before the AT is clear provided any points are in the correct position. They will also be restored to normal by the passage of a train.

Traditional calling-on signals are not controlled by track circuit, meaning that provided the interlocking allows it, they can be cleared irrespective of track circuit occupancy. They are not restored to the normal position by the passage of trains - the signaller must do this manually. The signallers' controls also differ in most cases, requiring the use of a Master Calling-On button at Sydney and Strathfield Signal Boxes. These COs are used primarily to keep trains moving past signals protecting points after track circuit failures, but also for shunting movements as required. The signal itself takes the form of a stencil 'CO' or, formerly, a banner or dwarf semaphore arm; some have been replaced with subsidiary yellow lights. Originally, the CO and S stencils were incorporated into the lower head of double light colourlight signals but are now typically in a separate lampcase. The Emergency Shunt Function provided at some locations works in a similar manner but invariably with subsidiary yellow light signals.

In the absence of anything clearly designating a subsidiary signal as "calling-on" such as the letters C, CO or a description on the lever plate, the use of that term to describe it is essentially informal and most likely will not be found on signal design diagrams.


The signaller sets up the calling onon his board and leaves it to run down mode, meaning it is activated on approach circuity. Once the timer has run down after being activated by loco- similar to the low speed, then the calling on will illuminate.
Still controlled by the signaller, as they have to set it up. Another example I can think of is Dunmore to enter the Boral siding. There is a run down timer here as well. Similar but not the same set-up.

The signaller can also manually give you the calling on from memory in this situation/location as well.
The idea with these timers is that you don't hold up other equipment like level crossings for an excessive period of time. The signaller is then free to go and attend to other duties.


The subsidiary signals being discussed are not approach controlled in this fashion, but such signals do exist. These particular signals can be cleared before a train has occupied the berth track circuit, i.e. in the absence of a train.
  rgmccau Junior Train Controller

Location: Canberra
Thanks for replies, cleared up a couple of points.  Now to reproduce things on my layout. Idea

Which raises the following question: (In diagram below)

http://flic.kr/p/keMUdR

What signals would be in the 2 spots?

I intend to have multi-head (Sydney Metro) style, and the lines are single direction (I have double track).  Everything is intended to be "normal running", so no calling on/slow speed/etc, and I have a measure of multiple sections, so multiple aspects - on the main, and could be on the branch, but not critical.  I'm after "simplistic" solutions rather than "rule-perfect", but I want more than red/green!  I'm also pretty good at electronics so making different things happen isnt a problem, but I'm not pedantic about "scale models", so getting a good enough signal is sufficient.

Signal A - 3 Aspect (R/Y/G) over 3 Aspect (R/Y/G)?
R over R - Stop
Y over Y - Branch - but no indication of advance sections
G over R/Y/G - Main

Signal B - I have no idea. 2 Aspect (R/Y - because it's joining back to the main?) over ....?
R over R - Stop
Y over ? - .....  How do I indicate Main vs Branch?

Any suggestions?
  KRviator Moderator

Location: Up the front
Both signal A and B would be standard 6-aspect double-colour light signals.

Any turnout indication says you're taking the branch line, any other proceed indication means your going down the main. Just because you're going through a set of trailing points doesn't mean you need a turnout indication. You can happily depart the loop on two greens.
  M636C Minister for Railways

As far as the Sydney examples go, "yes". They don't so much change colour as different LED's inside the signal light up as appropriate. So both of the examples pictured can show all of the signal indications as appropriate for the location, from full clear, preliminary medium, medium, caution and stop.
Raichase


While I'm not certain about Sydney Trains signals, I haven't observed any "black" LEDs when I have looked at signals fairly close up. In theory, if different LEDs lit up for different aspects, two thirds of the LEDs would be dark at any time, and these would be seen in between those lit up.

I know that for models, LEDs are available which show red with DC on one polarity, green on the other DC polarity and with both of these colours  illuminated with AC applied, it appears to be yellow. It would seem logical that a signal where the brightest light available would be wanted in daylight using all the LEDs with varying current would be the preferred option.

M636C
  HeadShunt Chief Train Controller

Just because you're going through a set of trailing points doesn't mean you need a turnout indication. You can happily depart the loop on two greens.
KRviator

True. Both setups can be found in NSW double light colourlight areas. I prefer an upper green for trailing points, with the yellow reserved for facing junctions.
  awsgc24 Minister for Railways

Location: Sydney
True. Both setups can be found in NSW double light colourlight areas. I prefer an upper green for trailing points, with the yellow reserved for facing junctions.
HeadShunt


The colours for trailing junction depends on the speed of the turnout compared to the line speed.

At the ARTC loop at Glenfield, the turnout appear to be high speed and the starting signal from the loop shows G/G.

At Gordon, the X40 turnout from the loop platform (P1) shows Y/Y as the line speed is 80.

At Chatswood, inconsistantly, the X80 crossover from P2 to the city shows Y/Y even though the line speed is probably 80km/h as well. Go figure.

There can also be a difference between a standing start from a deadend siding or platform and a through route from a branch line.
  HeadShunt Chief Train Controller

The colours for trailing junction depends on the speed of the turnout compared to the line speed.

At the ARTC loop at Glenfield, the turnout appear to be high speed and the starting signal from the loop shows G/G.

At Gordon, the X40 turnout from the loop platform (P1) shows Y/Y as the line speed is 80.

At Chatswood, inconsistantly, the X80 crossover from P2 to the city shows Y/Y even though the line speed is probably 80km/h as well. Go figure.

There can also be a difference between a standing start from a deadend siding or platform and a through route from a branch line.
awsgc24


It sounds logical. If only it were consistently applied. As you said, some have upper greens and others upper yellow, irrespective of the speed reduction required.

The other thing is that with a trailing junction there is only one route option. Under route signalling, drivers are supposed to have route knowledge, i.e. firstly to know that the points are there and secondly to know their speed. If there is only one route option, the speed through the points is effectively the line speed for that short section, and it should be well known by anyone on the footplate, just as they should be well aware of sharp curves that require hefty brake applications. Reliance on route knowledge can be taken too far and route signal indications can become ambiguous, e.g. Foxhall Junction 27 September 1967 and Concord West NSW, but they were overspeed derailments on facing points, not a convergence.

In fact, there are even some facing junctions or trailing junctions with trap points where I think an upper green would be more appropriate (ignoring the few "high speed" junctions in NSW). Again, where there is only one main route option, approach speeds are low or from a standstill, but it seems that since points are required reverse for the movement, it "must" have an upper yellow. There really is no need for the "whoa, slow down, points ahead!" cautionary effect of the upper yellow in such cases.

I suppose it might be cheaper to provide a Y/R+Y/R signal than G/R+G/Y/R/g, possibly with route indicators. Taking that further, it is probably also cheaper to simply hold the signal in rear at medium than resorting to the approach control method used in the UK. Having said that, I doubt the odd looking NSW single colourlight turnout signals combined with fixed reds found at converging junctions are cheaper than a standard three light signal head, which in many cases I'm sure could be substituted quite satisfactorily given the low speeds involved where many of them are used. Their four aspect capability would provide more information about the condition of the line ahead.
  awsgc24 Minister for Railways

Location: Sydney
There can also be a difference between a standing start from a deadend siding or platform and a through route from a branch line.
awsgc24


Thus IIRC the starting signal from the dead-end platform P1 at Macarthur shows R/Y/G towards the Up Main and R/BoY/PulsatingBoY to the down main. Turnout speed unknown.

Thus the starting signal from the dead-end platform P2 at Lindfield and P1 at East Hills show RR/YR/YY to the Up Main. Turnout speed unknown. Go figure.

The starting signal from platform P4 at Hornsby through X80 crossover shows Y/Y.
  rgmccau Junior Train Controller

Location: Canberra
Thank you all. 3 aspect over 3 aspect sounds like the simplest answer.

Ross McConchie
Canberra
  awsgc24 Minister for Railways

Location: Sydney

At Chatswood, inconsistantly, the X80 crossover from P2 to the city shows Y/Y even though the line speed is probably 80km/h as well. Go figure.
awsgc24


Correct after site visit: X75 not X80. Not sure what line speed on straight is.
  Raichase Captain Rant!

Location: Sydney, NSW
Correct after site visit: X75 not X80. Not sure what line speed on straight is.
awsgc24

80. There's a speedboard at the end of P1.
  awsgc24 Minister for Railways

Location: Sydney
80. There's a speedboard at the end of P1.
Raichase


So difference in speeds of 80 and X80 is less than 10 km/h, so the signal from P2 could be G/G.

However, should 4 tracks be extended from Chatswood to St Leonards and the second harbour rail crossing, G/G will be on the straight and Y/Y on the X85.
  Aurora8 Assistant Commissioner

Location: Sydney
So difference in speeds of 80 and X80 is less than 10 km/h, so the signal from P2 could be G/G.

However, should 4 tracks be extended from Chatswood to St Leonards and the second harbour rail crossing, G/G will be on the straight and Y/Y on the X85.
"awsgc24"

No G/G because there is a route straight ahead, but only for the terminal road. Although the speed may be X75 for the crossover, you're still crossing over onto another track hence turnout indication (Y/Y) on the signals.
  HeadShunt Chief Train Controller

No G/G because there is a route straight ahead, but only for the terminal road. Although the speed may be X75 for the crossover, you're still crossing over onto another track hence turnout indication (Y/Y) on the signals.
Aurora8


No doubt that is the case, but our point is that an upper yellow is not necessary where little or no reduction in speed for the points is required. As I said above, there are locations where an upper yellow is provided even where there is only one main route and little or no braking is necessary. If there is no need to brake, there is no need for the cautionary effect of the upper yellow, although its meaning as a simple route indication (obviating the need for a proper route indicator) is understood.
  FullSeries Assistant Commissioner

Location: Sydney, NSW
No doubt that is the case, but our point is that an upper yellow is not necessary where little or no reduction in speed for the points is required. As I said above, there are locations where an upper yellow is provided even where there is only one main route and little or no braking is necessary. If there is no need to brake, there is no need for the cautionary effect of the upper yellow, although its meaning as a simple route indication (obviating the need for a proper route indicator) is understood.
HeadShunt

Whatever they choose, it needs to be consistent. Cabramatta on the up, G/G with a Route Stencil. Even though its X80 for the Main South and 90 for the Old South.

Chatswood, Down Shore, G/G 80 for P4, Y/Y 80 for P3. Go figure.
  KRviator Moderator

Location: Up the front
Whatever they choose, it needs to be consistent. Cabramatta on the up, G/G with a Route Stencil. Even though its X80 for the Main South and 90 for the Old South.

Chatswood, Down Shore, G/G 80 for P4, Y/Y 80 for P3. Go figure.
"FullSeries"
Probably because platform 3 is located on the Down ECRL, not the Down Shore, and as we operate under a route signalling philosophy in NSW, requires the identification that you are diverging from the Down Shore to the Down ECRL?

Sponsored advertisement

Subscribers: Raichase, seb2351, wurx

Display from:   

Quick Reply

We've disabled Quick Reply for this thread as it was last updated more than six months ago.