GSMR - what do signallers see when a headcode is registered?

[martin2345uk]

As a driver I don't know what happens at the signaller's end when we register the head code into the GSMR... when you look at any of the online signal maps like Trays or Open Train Times, you see the train's head codes but they show even before registering so I guess it doesn't control that, what actually happens at the signaller's end when I enter say 9519 into the radio? Can they see I have done it? Does it just mean they can call me directly by dialling the head code?

 

[Port Road]

In older NX boxes the signaller inputs the headcode when they are ready to do so. In more modern 'boxes the system changes the incoming headcode to the next working headcode automatically. When you register on GSMR as far as I remember all that happens for the signaller is that your train headcode becomes 'live' on the GSMR touchscreen dialpad. (That is also a map, like Traksy, and there are numerous functions available, 'emergency call', input a recorded message, 'wait for signal' etc. Also we could make on board announcements on some trains in certain circumstances. To call a driver (or train manager on some trains) you just press the headcode on the touchscreen and select what you want to do.

 

[martin2345uk]

So if when you register the train tells you it's already allocated, ie maybe someone has inputted the wrong number into their train, could the signaller see which train that is and call them?

 

[RiverDon]

I don't know specific details of what they can and can't do but during my training I was taken to see a signalbox and the signaller showed us the GSM-R screen and how it works for them. If you don't get an answer here it might be worth trying to arrange a visit to your local signalbox through your DTM?

 

[martin2345uk]

I think I'd have more chance of arranging a visit to the Kremlin but we will see

 

[Geeves]

Certainly at my station we often have calls via the back to back radio to go to platform x "because the driver has not registered the gsmr". To me that says they can see from the head code on the GSMR terminal if a driver is in the cab or not? Maybe it comes up a green colour? I am going to arrange a trip to the ROC myself too and I will ask the questions ha. I have many

 

[RiverDon]

I think I'd have more chance of arranging a visit to the Kremlin but we will see

I must say in fairness details of the GSM-R didn't leave much of an impression on me because the whole thing was a bit overwhelming. All I can tell you is it's a touchscreen and they have a list of the trains in their area arranged by headcode (I didn't see a map but maybe that's on a screen we weren't shown?).

I have no idea how signallers manage to do that job, it looks immense. But the ones we visited were very friendly and patient in trying to answer questions. Good luck arranging something!

 

[Supercoss]

You may find this of interest whilst newer gsm-r signaller consoles are available the basics are the same -

 

[RailwayRookie]

So if when you register the train tells you it's already allocated, ie maybe someone has inputted the wrong number into their train, could the signaller see which train that is and call them?

As a signaller I was told it is possible for two trains to be registered with the same head code as they would be occupying different berths (albeit the same GSM-R cell area).
Ive never seen it myself as they try to avoid the same headcode on different trains in the same region anyway.

A note on your original post is a signaller should be able to call any cab thats 'on' regardless of registration by dialing the unit number.
It gets tricky of you have three 4 car MU's as theres 6 possible GSMR units and the signallers system wont tell you which one is on.

But essentially once you are registered you can be called from your headcode as the most common/easier way to do it

 

[D365]

It gets tricky of you have three 4 car MU's as theres 6 possible GSMR units and the signallers system wont tell you which one is on.

Is it necessary for a signaller to know which cab is opened? Given that it won’t be an intermediate cab.

 

[RailwayRookie]

Is it necessary for a signaller to know which cab is opened? Given that it won’t be an intermediate cab.

Only if they cant contact the driver via a registered headcode.

Theres no easy way of knowing which cabs are in the middle, the order of the units yes, but not if the A or B end is leading on that unit (unless you can extrapolate from TRUST or similar)

So for a pair of multiple units, it could conceivably be any of the 4 cabs leading. Obviously if its more than two MUs you can ignore the centre sets cabs, unless the driver is particularly talented...

 

[godfreycomplex]

I think I'd have more chance of arranging a visit to the Kremlin but we will see

PM sent

 

[endofthetunnel]

As a driver I don't know what happens at the signaller's end when we register the head code into the GSMR... when you look at any of the online signal maps like Trays or Open Train Times, you see the train's head codes but they show even before registering so I guess it doesn't control that, what actually happens at the signaller's end when I enter say 9519 into the radio? Can they see I have done it? Does it just mean they can call me directly by dialling the head code?

So in simple terms the registration of the train is to allow the system link your cab’s terminal to a specific berth in the signalling system. You tell it where you are, it checks there’s a head code there that’s the same, and then the two are linked.
It allows the signallers terminal to correctly show the location of the train and for it to ‘pair’ with the right base station when moving along the route.

Signallers don’t actually see anything until you are successfully registered. If they have put the wrong headcode in, the system will error, and then you call and they can change it and you’ll be fine. But the signaller won’t know it’s failing until you tell them.

If you register with a ‘wildcard’ the verification step is skipped, so you can register in a yard or siding for example where there are no headcode berths for the signaller to show. The risk of this (and why you in theory need permission) is that the system doesn’t know exactly where you are so there are many places with coverage of multiple GSMR masts and it won’t know the right one to pair with, just the closest. So this could be an issue if a REC went out for example.

Most freight and yard moves register like this, and that’s fine. Once they get properly on the network it can link the cab with the headcode and all is well, but until then a driver will ring through to their nearest mast rather than the appropriate one - especially an issue in complex locations, or for example big depots near the main lines.

There’s a lot more to it than that, if you want more details I can elaborate!

Edited to add - also always very happy to arrange drivers a visit to ROC, PSB or little lever frame box in my world, depending on your area of the country, welcome to PM

 

[68000]

Emergency calls go to every train radio in pre-determined cells whether registered or not. Registering means the signaller can see (& search) the headcode on the trains & mobiles list (it will show unit number if not registered). In train desriber areas, registering also allows calls to be routed to the controlling signaller.

 

[martin2345uk]

What exactly are "train describer areas"?

 

[PZ 08895]

Train Describer areas are the geographical area of track reported by a particular Train Describer (TD). The list of TDs is in the public domain and can be viewed here: https://wiki.openraildata.com/index.php/List_of_Train_Describers

Generally a small area signalling centre will have a TD, a larger signalling centre / ROC will have multiple TDs and a geographic 'cluster' of mechanical signal boxes will be reported by one TD, typically in a fringe signalling centre.

GSM-R uses a process called Location Dependent Addressing (LDA) to route non-emergency calls to the signaller associated with the TD berth the train is occupying when it makes the call. Therefore a call from a train should go to the signaller responsible for that train at the moment of time the call is made. Similarly, the signaller can consult the train list on their GSM-R terminal to see what trains they have in their are of control. LDA works using the initial radio registration process described by endofthetunnel above, which unless a wildcard is used, checks that the train description and signal berth entered by the driver at registration corelates with the TD data. If when registration is attempted the signaller at the train start location has not yet interposed the train description into a signal berth (in some locations done automatically) this called registration will fail initially as it will not corelate, as again described by endofthetunnel, this is fixed by the signaller then adding the train description into the applicable berth. After registration the GSM-R Fixed Terminal System will keep track of the train as it steps from signal berth to signal berth throughout its journey to enable calls to be routed correctly. As the TD system does not have sufficient safety integrity, Railway Emergency Calls (REC calls) uses cell-based routing. This associates the GSM-R cell where the REC call was made with a signaller's terminal - most of the time this will be the correct signaller, but it is straightforward to deal with if not.

​