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Unread 28-05-2019, 15:40   #6
Mark Gleeson
Technical Officer
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Join Date: Dec 2005
Location: Coach C, Seat 33
Posts: 12,652

So 10 hours on the system is still not fixed, while Irish Rail says it is using 'manual signaling' it really means without the computer, we are not talking about flags and lamps. It is perfectly safe (in fact there is no difference vs normal)

The main signaling console which controls Dublin Heuston to Athy/Athlone/Limerick/Cork failed at 0530 this morning and reversion to some form of backup took about 2 and a half hours, even longer in the case of Athlone.

The system is mostly automated and a computer reads the timetable and tells the signaling system how to route the trains, this is called auto route setting, ARS is the industry. Signaling staff mostly supervise and intervene for delays or other disruptions.

If this fails the signaling staff perform everything through a computer terminal relying on the train describer to know which train is which, each train has an id number which is shown in the internal timetable and the number alone is normally enough to know the trains type and destination. It is possible to maintain a full service here with some care.

If the train describer fails then things become challenging and itís back to pen and paper, easy on a single tracks route, very challenging at a major terminus or junction. Some routes operate in this manner permanently.

If the computer goes down, and bearing in mind the computer has no safety function at all there are emergency control points around the network usually in a container or block house.

Inside there is an old style mimic panel (pre 1995) or a computer terminal. The signalman turns a switch in the room to local which means the computer cannot control anymore but can see what is going on. the signal person controls locally relying on old style bell communication to the adjacent signal box. In this case while possible to maintain full service it is extremely challenging and it assumes Irish Rail has sufficient staff trained.

In all cases itís just a different way to tell the signaling system how to route a train, the signaling system itself provides the safety critical protections not the control centre computer

All of this relies on adequate trained and experienced staff. Fully manual control from the emergency control point is very rarely used. This is the problem lack of experience.

Last edited by Mark Gleeson : 28-05-2019 at 16:14.
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