'X' Signals

[Ex LT]

Can anyone give a description of a normal well so called normal 'X' signal the one referred to as the last automatic signal before a controlled area which it is not always the case.

 

[Dstock7080]

‘normally’ the last automatic, not always.
To prevent a driver applying the appropriate Rule and entering a controlled area and potentially locking-up the signal frame.

X-signals were also in areas where auto-running could be applied, sun-surface train detectors and in floodgate areas.

 

[bramling]

Can anyone give a description of a normal well so called normal 'X' signal the one referred to as the last automatic signal before a controlled area which it is not always the case.

It is generally the last auto before the *sighting point* of the first semi. This is why it isn’t always the last one, though often is.

 

[Ex LT]

‘normally’ the last automatic, not always.
To prevent a driver applying the appropriate Rule and entering a controlled area and potentially locking-up the signal frame.

X-signals were also in areas where auto-running could be applied, sun-surface train detectors and in floodgate areas.

Dstock7080 yes although those other ones you mention are specific and there have been many more TRX, PNX being just two so you could easily explain them but the normal one I use the term lightly like you say was to stop the driver applying the rule and locking up the signals but some areas did not have any at all. A 'FNX' as an example you would say is a floodgate signal but an 'X' signal would you just say it's an 'X' signal can it be briefly explained.

It is generally the last auto before the *sighting point* of the first semi. This is why it isn’t always the last one, though often is.

bramling now what you say is interesting as I have never heard that explanation before can you tell where you heard it please.

 

[bramling]

Dstock7080 yes although those other ones you mention are specific and there have been many more TRX, PNX being just two so you could easily explain them but the normal one I use the term lightly like you say was to stop the driver applying the rule and locking up the signals but some areas did not have any at all. A 'FNX' as an example you would say is a floodgate signal but an 'X' signal would you just say it's an 'X' signal can it be briefly explained.


bramling now what you say is interesting as I have never heard that explanation before can you tell where you heard it please.

Can’t remember to be honest, however it would have been from inside the signalling fraternity, so a reliable source. It makes perfect sense, and accords with what exists on the ground.

 

[Dstock7080]

Very simply they were automatic signals that you did NOT want the driver to apply the automatic signal stop & proceed Rule on.

The only plain “X” with no cabin code i know is at Barons Court eastbound X647C which would remain at danger if the surface stock train detector was broken.

 

[Ex LT]

Very simply they were automatic signals that you did NOT want the driver to apply the automatic signal stop & proceed Rule on.

The only plain “X” with no cabin code i know is at Barons Court eastbound X647C which would remain at danger if the surface stock train detector was broken.

Dstock7080 sorry I did not make myself clear I did not mean X by itself the ones that have the code for the area i.e. MBX etc would you just say that is the last automatic or give another explanation sorry for the confusion. Unless they have been renumbered I can think of 2 more that are just plain X, Waterloo SB Bakerloo X341 and Hounslow West WB X412A which is like Barons Court.

Can’t remember to be honest, however it would have been from inside the signalling fraternity, so a reliable source. It makes perfect sense, and accords with what exists on the ground.

Thanks for that and yes makes perfect sense.

 

[Mojo]

Dstock7080 yes although those other ones you mention are specific and there have been many more TRX, PNX being just two so you could easily explain them but the normal one I use the term lightly like you say was to stop the driver applying the rule and locking up the signals but some areas did not have any at all.

There’s a few more on the Picc. On the T5 extension, X402 on the Westbound and X399 on the Eastbound are to prevent multiple trains entering the same section because of intervention/ventilation shaft in the area, there are also X400a, X400b, and X400c approaching (and part way into) the platform at T5 Westbound. Further up the line on the Eastbound you have X855 between Manor House & Turnpike Lane and X883/X887 between Wood Green & Bounds Green. These are/were to protect the former Piccadilly East End Computer Signalling system (Peecs), as two trains entering the same track circuit section and then the one ahead leaving caused the system to throw a wobbler.

A 'FNX' as an example you would say is a floodgate signal but an 'X' signal would you just say it's an 'X' signal can it be briefly explained.

Does the ‘N’ refer to Northern, as the floodgate signals on the Picc are all FPX? I’m guessing as the Bakerloo line signalling was done/rationalised more recently that is why the floodgate signals are X signals, as in X341 as you’ve mentioned, additionally X signals on the Bakerloo X355 approaching Embankment, and X345/X326 approaching Waterloo. Interesting the Victoria line uses the suffix ‘F’ to denote floodgate signals; not sure what the equivalent signal numbers were before resignalling.

 

[Ex LT]

There’s a few more on the Picc. On the T5 extension, X402 on the Westbound and X399 on the Eastbound are to prevent multiple trains entering the same section because of intervention/ventilation shaft in the area, there are also X400a, X400b, and X400c approaching (and part way into) the platform at T5 Westbound. Further up the line on the Eastbound you have X855 between Manor House & Turnpike Lane and X883/X887 between Wood Green & Bounds Green. These are/were to protect the former Piccadilly East End Computer Signalling system (Peecs), as two trains entering the same track circuit section and then the one ahead leaving caused the system to throw a wobbler.


Does the ‘N’ refer to Northern, as the floodgate signals on the Picc are all FPX? I’m guessing as the Bakerloo line signalling was done/rationalised more recently that is why the floodgate signals are X signals, as in X341 as you’ve mentioned, additionally X signals on the Bakerloo X355 approaching Embankment, and X345/X326 approaching Waterloo. Interesting the Victoria line uses the suffix ‘F’ to denote floodgate signals; not sure what the equivalent signal numbers were before resignalling.

Yes the 'N' does indicate Northern and the Piccadilly is FPX like you say on the Bakerloo they resignalled many years ago and just had 'X'. X341 as far as I know is nothing to do with the floodgates but it can be maintained at danger from Baker Street CR.

The Victoria line used FX before the upgrade.

The Piccadilly line had many problems at the east end until they put those signals in. T5 another issue I had forgotten about.

 

[REVUpminster]

As said before it is the last automatic before a controlled area and if passed at danger (RED) the train could find the semi automatic ahead at green and the train would approach lock the points. The signaller could not return the signal to normal so that he would be unable to move the points although he can get the lever far enough back to display a red signal.

Provided the train had stopped short of the points, or track locking would come into play, the signaller can take a release which takes a few minutes.

Approach locking, Route/ back locking, and track locking are all to stop a signaller operating the points as a train passes over. mechanical locking is within the frame to prevent the signaller making a conflicting move.

Approach and route locking work when the semi is green. track locking when the signal is red.