Nationwide GSMR outage 19/05

[choochoochoo]

Our TOC supplies telephone numbers for signallers in case of emergency. TVSC are happy to be contacted that way if necessary. So long as you have GSMR-GB you will still receive RECs. What happened the other day for my TOC was that most if not all trains were held at signals. Protocol dictates use of GSMR, portable GSMR, SPTs then mobile. A call to control informed me of the problem. A call to the signaller then set expectations. It was over in 30 minutes.

I'd have thought work mobile over SPT makes more sense. It’s safer than going on or near the line to make a call (unless SPT at a station). Then you’re relying on the SPT actually working when you try to use it.

 

[E27007]

I am not aware of any indications on a panel, including the train describer displays, that are dependent on the GSMR. I understand that the GSMR gets data from the train describer, but not the other way around.

I do not have detailed knowledge of the working of GSMR, at the start of a journey, and when opening up the cab, the Driver registers with the signalling system with detail of the headcode of the movement and the number of the signal if berthed at a signal, a wildcard number if there isn't a suitable signal. At the end of the journey, the Driver deregisters the headcode, the system is geographical in operation, but not foolproof, just one example phoning a Signaller while standing at Peckham, a Victoria panel area, Romford box responded.

 

[Belperpete]

I do not have detailed knowledge of the working of GSMR, at the start of a journey, and when opening up the cab, the Driver registers with the signalling system with detail of the headcode of the movement and the number of the signal if berthed at a signal, a wildcard number if there isn't a suitable signal. At the end of the journey, the Driver deregisters the headcode, the system is geographical in operation, but not foolproof, just one example phoning a Signaller while standing at Peckham, a Victoria panel area, Romford box responded.

The train describer system (in panel boxes this is usually a standalone system, in vdu control centres it is now just one part of the control system software) is what moves the 4 character train descriptions around the panel as the trains move. The descriptions are usually entered manually by the signaller at the start of the journey, but in those boxes with Automatic Code Insertion the train describer may do it automatically. As far as I am aware, the train describer does not rely on the GSMR for its operation, the train describer will keep happily working without GSMR (and many TDs were installed before GSMR even existed).

The GSMR system knows the unit identity of the train it is installed in, but that is not how signallers usually contact the train. They know trains by their train description as displayed on the panel by the train describer, or its position at a certain signal, they won't readily know what unit that train is being worked by, or it's GSMR "phone number" At the start of a journey, the driver therefore has to register the train description for that service with the GSMR system. The GSMR system can then correlate the train's "phone number" with the unit number, train description and location (the train describer berth that description is currently being displayed in, usually based on the signal number). As the train moves along it's journey, the train describer will keep the GSMR system updated with the location of it's train description. So if at any point, if the signaller wants to contact train 1A23 or the train standing at signal S456, the GSMR will know which GSMR radio unit to call.

Likewise if the driver asks to call the signaller, the GSMR should know where that train is in railway terms, i.e. which signal berth it's description is stored in, and therefore which signaller is responsible for it. I suspect that the reason that you may occasionally get the wrong signaller could be because say both Victoria and Romford have trains with the same train description on their patch.

 

[crablab]

The GSMR system can then correlate the train's "phone number" with the unit number, train description and location (the train describer berth that description is currently being displayed in, usually based on the signal number). As the train moves along it's journey, the train describer will keep the GSMR system updated with the location of it's train description. So if at any point, if the signaller wants to contact train 1A23 or the train standing at signal S456, the GSMR will know which GSMR radio unit to call.

GSM-R is just railway specific 2G. When dialling a handset GSM already knows which cell to route to because the handset is registered with the network via one or multiple cells (ie. a tower)

I believe* the geographical information available from cell registration is used for call routing (eg. to the correct signaller for a section) and things like REC (which is a cell broadcast to handsets registered on that cell).

Again, these are "features" of GSM and have nothing to do with signalling or train describers .

 

[GraphitProjekt]

How does automatic code insertion work, which I also believe is a lot older than GSMR?

 

[150219]

How does automatic code insertion work, which I also believe is a lot older than GSMR?

Way off topic for this, but putting it very simply it's either hardwired by programming code (ACI) or the more revolutionary (WACI) which works it all out by logic (mostly!).

 

[edwin_m]

How does automatic code insertion work, which I also believe is a lot older than GSMR?

In IECCs it's done from the timetable that the Automatic Route Setting uses, which knows the planned next working. I assume it's similar in other VDU-based systems with automatic route setting.

 

[Belperpete]

GSM-R is just railway specific 2G. When dialling a handset GSM already knows which cell to route to because the handset is registered with the network via one or multiple cells (ie. a tower)

Correct about it being 2G. However, as previously explained, the signaller does not dial the train's mobile phone number. They will select the train description or the location of the train that they want to call, and the GSMR system will convert that into the mobile number based on information it gets from the train describer.

I believe* the geographical information available from cell registration is used for call routing (eg. to the correct signaller for a section) and things like REC (which is a cell broadcast to handsets registered on that cell).

While in most cases the location derived from cell registration could be used to identify the correct signaller, there are many places where it can't, e.g. at signalbox boundaries, or where routes controlled by different control centres run close or cross one another.

Again, these are "features" of GSM and have nothing to do with signalling or train describers .

However, as explained previously, these features require information from the train describer system to function correctly.

To get back to the original point, however, I am not aware of any way in which a GSMR outage or fault could affect the indications on a signallers panel.

 

[crablab]

They will select the train description or the location of the train that they want to call, and the GSMR system will convert that into the mobile number based on information it gets from the train describer.

AIUI this is a lookup table; at registration of the handset the headcode is associated and can be used as a call alias.
Call routing in GSM is not dependant on the signalling system, which is what your post above seemed to be suggesting

 

[Horizon22]

I do not have detailed knowledge of the working of GSMR, at the start of a journey, and when opening up the cab, the Driver registers with the signalling system with detail of the headcode of the movement and the number of the signal if berthed at a signal, a wildcard number if there isn't a suitable signal. At the end of the journey, the Driver deregisters the headcode, the system is geographical in operation, but not foolproof, just one example phoning a Signaller while standing at Peckham, a Victoria panel area, Romford box responded.

GSMR is based on cells which are crudely geographically circular in nature. Hence Railway Emergency Calls (REC) can knock out adjacent but completely unconnected lines. In normal running they are normally more specific, but not infallible..

 

[merry]

I'd have thought work mobile over SPT makes more sense.

The SPT gives a signaller an absolute fix on the driver’s location, to the exact signal post (although it may serve multiple lines, the options are limited). A mobile phone requires extra conversation to confirm the train location which represents an extra risk of misunderstanding.
Therefore heirarchy is most to least precise: GSMR (gps and vehicle/ID exactly), SPT (exact location, train ID by voice description), mobile phone (all details by voice).

 

[Mattplans]

What's causing all of these outages, is it just coincidence?

SWR responding to SWR watch (passenger interest group) about recent GSMR incident:

Full document here: https://x.com/swtrains_watch/status/2063982646409953314

2. Prevention and Security

Network Rail Position: Traced to a faulty hardware card installed during an overnight upgrade. It was a technical fault, not a security breach, and safety was never compromised.
Do you have any further information to add to help passengers understand what went wrong and what is being done to reduce the chance of this happening again?
The actual cause was a GSM-R base station control failure. Teams are putting additional resilience in to minimise the risks of this happening again.

 

[68000]

AIUI this is a lookup table; at registration of the handset the headcode is associated and can be used as a call alias.
Call routing in GSM is not dependant on the signalling system, which is what your post above seemed to be suggesting

Call routing in non-Train Describer areas and unregistered trains is Location Dependent Addressing (LDA) which is essentially cell based routing. Every cell will be configured to route calls to a certain signaller. Call routing in TD areas and registered trains is enhanced LDA (eLDA) which uses the TD berth information to route the call to the signaller.