OFF PLATFORM INDICATOR what for?

[merlodlliw]

While waiting to collect a passenger off the three o clockish arrival from Cardiff on platform 2 at Wrexham General yesterday(2x 150 plus 2x 158s) there was
a good number of passengers awaiting the 3.27? W/S departure for Marylebone due on platform 3 soon after the ATW had left.

Anyhow I noted a brand new UP departure board on platform 3, which reads OFF both sides when illuminated, I persuaded my friend to go & have a coffee at the W/S cafe, due to the ATW having no trolley service & packed with passengers under enthused with the pair of 150s provided for the 5 hour plus journey.

I decided to watch the arrival of the W/S which had about ten minutes on platform 3 before returning to Marylebone(the loudspeakers bi ling never say LONDON Marylebone, another wag directive one wonders), I noted the train manager about two minutes before departure go to a box under this new 27KG OFF sign,he appeared to press a code in, then after a minute the sign lit up
OFF, and the train departed, my question is what is the main use of this off indicator, it also appeared some coloured lights had been removed from the up end of platform 3. Does it simply mean like in the old days, the signalman had pulled off, as the porters used to say.
BTW the train from platform 3 passes over the down line for a few hundred meters before switching to the up line and through the Giant Maelor base hospital level crossing at Cross Newydd,

M

 

[CarterUSM]

While waiting to collect a passenger off the three o clockish arrival from Cardiff on platform 2 at Wrexham General yesterday(2x 150 plus 2x 158s) there was
a good number of passengers awaiting the 3.27? W/S departure for Marylebone due on platform 3 soon after the ATW had left.

Anyhow I noted a brand new UP departure board on platform 3, which reads OFF both sides when illuminated, I persuaded my friend to go & have a coffee at the W/S cafe, due to the ATW having no trolley service & packed with passengers under enthused with the pair of 150s provided for the 5 hour plus journey.

I decided to watch the arrival of the W/S which had about ten minutes on platform 3 before returning to Marylebone(the loudspeakers bi ling never say LONDON Marylebone, another wag directive one wonders), I noted the train manager about two minutes before departure go to a box under this new 27KG OFF sign,he appeared to press a code in, then after a minute the sign lit up
OFF, and the train departed, my question is what is the main use of this off indicator, it also appeared some coloured lights had been removed from the up end of platform 3. Does it simply mean like in the old days, the signalman had pulled off, as the porters used to say.
BTW the train from platform 3 passes over the down line for a few hundred meters before switching to the up line and through the Giant Maelor base hospital level crossing at Cross Newydd,

M

More or less. The off indicator signifies that the signal ahead is 'off' and i'm guessing that the train manager pressed the Train Ready To Start (TRTS) button in the wee box to which you refer. This lets the signalman know the train is manned and ready To depart, at my location, this button should be pressed around 2 minutes before departure. Check railsigns excellent site, it is full of interesting and concise information about lineside signals, indicators, boards etc.

 

[krus_aragon]

The OFF indicator is provided to help a dispatcher know if the signals have cleared, as, due to station layout etc., they can't see both the full length of the train and the signal in question at the same time. The curved platforms at Llandudno Junction have these indicators, but the curvier Colwyn Bay ones don't as the station's in the middle of a block section (no signal to see).

 

[merlodlliw]

The OFF indicator is provided to help a dispatcher know if the signals have cleared, as, due to station layout etc., they can't see both the full length of the train and the signal in question at the same time. The curved platforms at Llandudno Junction have these indicators, but the curvier Colwyn Bay ones don't as the station's in the middle of a block section (no signal to see).

thanks both, all we want now are arrival boards, as Wrexham Gen is also a terminus for five London services(4 down/one up), after booking office closes, one as no idea if the services are on time, or in the VT case, if it will marry with the up stopper. PS railsigns is excellent.

M

 

[mumrar]

This post has made me think of something else, the unique signals at Kings Cross. They're positioned on the right hand side of the tunnel mouths if you were leaving the station, and they light up showing the platform number of trains arriving from the tunnels. Certainly never seen anything like it elsewhere, would be useful at New Street lol.

 

[merlodlliw]

This post has made me think of something else, the unique signals at Kings Cross. They're positioned on the right hand side of the tunnel mouths if you were leaving the station, and they light up showing the platform number of trains arriving from the tunnels. Certainly never seen anything like it elsewhere, would be useful at New Street lol.

I am sure they had some kind of platform number indicator on the way into Euston, pretty sure I saw this, cant recall the date.Could be years ago.

I have since received this information via helpful local contacts in the trade, below (ref Off sign)
........................................................................................................

Not to be attributed to me - an explanation as follows.


Prior to the “Off indicators” the train crew rang the signalman to let them know they were ready to depart. The OFF indicator is better (quicker comms). With the Croes Newydd project Network Rail put them in on three and one. Two minutes prior to departure you “bell out” (or “press the plunger”) this identifies to the signal man that you are ready for departure, the two minutes should be sufficient time for him to give you the path which will be identified by the green proceed aspect and the “OFF” indication which are linked together (the “OFF“ is halfway down the platform so clearly visible to the Train Manager”.

.................................................................................. and another
The OFF signal is in effect a repeater for the starter signal which is now relocated off to the right of the line and cannot be seen by platform staff because the loco or dvt is in the way.
the guard will have advised CN box the train is ready to depart and, if all other factors are in place, the green will be given to the driver and repeated by the OFF.
The alternative for an OFF indicator is ON meaning a red will be showing on the signal although I don't think the ON is shown at WXH Gen platform 3.
.................................................................
Now I know chapter and verse.

M

 

[Aictos]

May I point out as a dispatcher the very basics of the Off indicator?

If it is lit and reads OFF then it means a proceed signal is available for that route regardless if TRTS is used or not.
If it is not lit then it means the signal is at danger and the dispatch process should not under any circumstances be started unless under the express permission of the signaller.

Take Stevenage for example, they have a OFF indicator for Platforms 1 and 4 because a 8 car blocks the signal on Platform 1 and 4/8/12 cars blocks the signal on Platform 4.
Also note no TRTS is available at Stevenage as the OFF indicator is controlled by whatever the signalman sets the connected signal for.

 

[jopsuk]

There's a whole page on these indicators at Rail Signs

Platform/route indications are widespread- see here for more information
(it's a fantastic site, if difficult to search)

 

[Tomnick]

Not aware of such a thing as an 'ON' indicator - as stated already, an 'OFF' indicator informs platform staff/the Guard when the platform starter is showing a proceed aspect, which is what they need to check before dispatching. They don't specifically need to know that the signal is at Danger (i.e. 'on'); in any case, that'll be inferred by the absence of an 'OFF' indication (thus, it's also failsafe).

 

[GB]

They don't specifically need to know that the signal is at Danger

They do indeed need to know if the platform signal is at danger to prevent them signalling to the driver to proceed.

 

[TDK]

The OFF indicator is better (quicker comms). With the Croes Newydd project Network Rail put them in on three and one. Two minutes prior to departure you “bell out” (or “press the plunger”) this identifies to the signal man that you are ready for departure, the two minutes should be sufficient time for him to give you the path which will be identified by the green proceed aspect and the “OFF” indication which are linked together (the “OFF“ is halfway down the platform so clearly visible to the Train Manager”.

There isn't an "OFF" indicator on P1 at Wrexham but there is a TRTS. this TRTS was installed to minimaise the time the barriers are down at Wavely Road crossing

The OFF signal is in effect a repeater for the starter signal which is now relocated off to the right of the line and cannot be seen by platform staff because the loco or dvt is in the way.
the guard will have advised CN box the train is ready to depart and, if all other factors are in place, the green will be given to the driver and repeated by the OFF.
The alternative for an OFF indicator is ON meaning a red will be showing on the signal although I don't think the ON is shown at WXH Gen platform 3.

I have never seen or heard of an "ON" indicator, would be interesting if someone could tell us where one is?

 

[Aictos]

They do indeed need to know if the platform signal is at danger to prevent them signalling to the driver to proceed.

I disagree, the OFF indicator should not display OFF if the signal is at danger so there is no need to see what the signal is displaying, in most cases the OFF indicator is there because the view of the signal is restricted.

No dispatcher in their right mind and this goes for guards would dispatch a train from a platform using such equipment and it wasn't displaying OFF unless of course in exceptional circumstances which if that's the case a certain set of guidelines for that location comes into play.

 

[ainsworth74]

I have never seen or heard of an "ON" indicator, would be interesting if someone could tell us where one is?

Railsigns suggests that it no longer exists on the national network.

 

[charlesn132]

The alternative for an OFF indicator is ON meaning a red will be showing on the signal although I don't think the ON is shown at WXH Gen platform 3.

On indicators don't exist any more according to railsigns: http://www.railsigns.co.uk/sect22page1/sect22page1.html

 

[merlodlliw]

I have never seen or heard of an "ON" indicator, would be interesting if someone could tell us where one is?[/QUOTE]

a bit about it here. http://www.railsigns.co.uk/sect22page1/sect22page1.html

 

[ainsworth74]

I find it funny that 3 of us have all said the same thing, and 2 of us have linked to the same web page!

 

[GB]

I disagree, the OFF indicator should not display OFF if the signal is at danger so there is no need to see what the signal is displaying, in most cases the OFF indicator is there because the view of the signal is restricted.

No dispatcher in their right mind and this goes for guards would dispatch a train from a platform using such equipment and it wasn't displaying OFF unless of course in exceptional circumstances which if that's the case a certain set of guidelines for that location comes into play.

I never said it should display "off" if the signal is still at danger as this would negate the point of such an indicator.

 

[Tomnick]

They do indeed need to know if the platform signal is at danger to prevent them signalling to the driver to proceed.

They need to know when the starter's off in order to dispatch the train - a specific 'ON' indication is unnecessary as the absence of an 'OFF' indication is sufficient if they check for that before dispatching. Interesting to see that 'ON' indicators were originally used though, although they quickly became obsolete.

 

[90019]

and i'm guessing that the train manager pressed the Train Ready To Start (TRTS) button in the wee box to which you refer.

I'm assuming that this is what's used to activate the crossing at Kingsknowe for trains heading towards Glasgow that stop there?

 

[GB]

They need to know when the starter's off in order to dispatch the train - a specific 'ON' indication is unnecessary as the absence of an 'OFF' indication is sufficient if they check for that before dispatching

That is what I ment. They do need to know if the signal is on but a sepertate "on" indication is not required.

 

[Tomnick]

It looks like we're agreeing! My point was that a positive off indication was the crucial part; although they obviously need to avoid dispatching against a red, they'd be assured of that if they waited for the 'off' indicator to illuminate.

Many AHBs with stopping/non-stopping controls (as at Kirknewton, i.e. interlinked with the signal in rear) are simply designed with a timer on the approach track circuit, so that in theory the barrier sequence starts in time to allow the signal to clear as the train would normally be ready to start. I don't see why a TRTS plunger couldn't be provided instead for stopping trains; indeed, that might well be the case somewhere on the network.

 

[CarterUSM]

I'm assuming that this is what's used to activate the crossing at Kingsknowe for trains heading towards Glasgow that stop there?

Yes, spot on, Kirknewton also.

 

[First class]

Is there not an 'On' indication on the Lakeside & Haitherwaite railway at Haitherwaite under the footbridge, attached to the semaphore??

 

[142094]

The OFF indicator is provided to help a dispatcher know if the signals have cleared, as, due to station layout etc., they can't see both the full length of the train and the signal in question at the same time. The curved platforms at Llandudno Junction have these indicators, but the curvier Colwyn Bay ones don't as the station's in the middle of a block section (no signal to see).

Doesn't just have to be platform despatchers, Northern guards at Newcastle and other stations self-despatch, so they press the plunger to get the signaller to put the platform starter as off. The OFF then illuminates to let the guard know they can shut the doors. If the platform starter stays as on, the guard most of the time waits with doors open at the platform. As you say it also happens at curved platforms, but not always.

Was at York on a Northern service once, about 15 minutes after we were timetballed to leave the guard came on to say that we were waiting for the signaller to give us a path - apparently we had missed our slot as either no-one had pressed the plunger or the signaller had forgotten about us.

 

[Railsigns]

Re. "On" Indications:

As mentioned on my website, the Southern Railway used them. Here's an extract from the 1928 resignalling notice for London Bridge:

Another notice issued in 1942 refers to the abolition of the "On" indications at Cannon Street and Charing Cross stations.

London Underground signalling isn't really my thing, but somewhere I've seen a reference to an "On" indicator at Moor Park. Maybe LU still use them?