Hi all, I'm on the Network Rail GSM-r installation team.
First of all there is a difference between the signallers response to the REC button (Railway Emergency Call) and the DSD alarm.
Pressing the REC button will set off an Emergency call to all drivers in the area (3 cells as mentioned previously) to stop immediately.
There are obvious implications to this, ie a cleaner on a depot might accidently press the button while cleaning the head.
Scotrail have been trialling the system for approx. 3 years now and due to a number of spurious REC button calls they have asked for a trial of a flap to cover the button, or a shroud with a deeper surround printed with 'Emergency Call Only' on it.
These have just been completed around the country and the feedback from drivers is being analysed.
The DSD alarm does not set off an immediate alarm, but sends an alarm to the signaller's console. The oficial wording is;
The GSM-R radio has an alarm function linked to the Driver’s Safety Device (DSD) which will alert the Signaller should the driver become incapacitated. The Signaller receives a DSD Alarm as a high priority call which sets off a distinctive alarm on the GSM-R terminal. The Signaller is required to respond with an Urgent priority call back to the cab to ascertain that the Driver is ok or needs assistance. If no response is forthcoming, the Signaller may need
to summon assistance to visit the cab and check that the driver is fit to continue.
If you are doing maintenance on the units where you usually leave the original DSD alarm sounding, wait 30 seconds until the GSM-R control panel says 'preparing DSD alarm, press X to cancel'.
If you cancel it by pressing X at this point, the DSD alrm will not go off again, and you can do your maintenance as usual.
Some depots are changing the VMI's to reflect this, some depots are instructing the maintainers to isolate the GSM-r before carrying out the checks.
Most (all?) the driver's I've come into contact with the system so far have been very positive about it. If you have any queries or concerns I'll try and answer them, or I will find out.