Great Western Coffee Shop

Just breaking news of a collision between a TGV and a regional express. Location currently no more specific than southwest France. Presumably if a regional train is involved it is not on an LGV, so I do hope this is not too severe.

http://m.bbc.co.uk/news/world-europe-28358137 (http://m.bbc.co.uk/news/world-europe-28358137)

edit - added URL & title updated

Reports say that the TER ran into the back of the TGV at 17:38 CET(S). Both had left Pau towards DAX and then Paris. So far casualties are given as about 20 injured, 3 gravely. I-Tele has a picture of the TER (http://www.itele.fr/france/video/collision-tgvter-3-blesses-graves-88660).
(http://www.itele.fr/content/upload/redactor/images/53c81479908edTERSudOuest.jpg)

I see nice evidence preservation and nice cordon enforced.

The latest figures are 40 injured, 4 seriously. Earlier, there were contradictory accounts of an announcement made in the TGV. Now, it seems that the TGV stopped and restarted very slowly, due to signalling problems. This in turn was attributed to the temperature (35C or more).

So once again it starts to sound a bit familiar. The director of safety at SNCF, Alain Krakovitch, has said that a signal was stuck on red. The procedure for passing this would have limited the TGV to 30 km/hr, but the TER struck it at 90 km/hr. So the question becomes: what did the TER driver see, or what were his communications with control?

He also said "it was an absolutely exceptional accident - unprecedented even", which can't be true. He, of all people, ought to appreciate that, when you manually override a safety system, human error comes back in as a potential cause of accidents. 

Here's a better English-language report, though its content is yesterday's: from IRJ (http://www.railjournal.com/index.php/europe/french-investigate-rear-end-train-collision.html).

This, from 20 minutes (http://www.20minutes.fr/societe/1419895-collision-ter-tgv-pres-de-pau-suivez-les-explications-de-la-sncf-et-rff-en-direct), is an update (in French).

It says that a previous TER and the TGV followed procedure when they found a signal stuck on red - stop, call the control centre, and get permission to proceed with caution (able to stop on sight). The following TER did stop, but then set off again at full speed. No reason for this is given.

The obvious reason (speculating slightly) would be that the fault cleared itself. You need a procedure that can cope with that - e.g. a call from control to warn this driver before he gets there. This report does not say explicitly that no call to control was made, nor mention a call from control.

As ever, we'll just have to wait for more facts.

Shame the BBC still cannot get the basic facts correct though, 24 hrs on and they still have the TGV running into the local train.

Paul

It's an odd signalling system that clears a fault and then sets a signal to off when the next section is occupied.

Does the TER stock have in-cab signal display like the TGV?

OTC

Female officer, standing astride a rail, no high viz but sporting a pistol on her thigh ... yes, that works.  ;) :D ;D

I think you are reading too much into my comment. I was really just referring to any recovery process from a fault, which may be not 100% engineered into the equipment and need human intervention and well-designed procedures as well.

Specifically, I think this line uses axle counters. When reset, or powered down and up, these always start with zero nett count - i.e. "clear". Something has to turn that into showing "unsafe" (i.e. there may or may not be a train in the section; there is no way of knowing). That can be built into the axle counter system, or into the surrounding system.

I have seen a recovery process that requires a train to go through the section and have the nett count go up and back down to zero before the section can be signalled as "clear". I also understand there has been a long-running debate about whether this reset process can be automatic, or done by signallers, or whether it needs a signals technician to do it.

It is also true that this may actually be an odd system, in that it is the French "BAPR" or "Block Automatique ^ Permissivit^ Restreinte". This is a simplified version of a full automatic block system ("BAL" in France), for lightly-used rural lines, and includes some provision for passing danger signals with caution. That would have been important before cab radios, and where getting a technician out to look at a fault could take ages. 


I'm sure this line just has the basic BAPR/BAL signalling, and any other signalling systems in either train will not be operating here.

I can only find two minor points to add from reports: the signal was installed in 2008 (but if that's just the signal head, it is hardly relevant), and there is a statement that the signal did clear to green before the TER set off.

However, that comes from the CGT (the main railway union),and they also say that neither the driver nor the signal technician working on this signal at the time was at fault - "respected all the safety procedures". They go on to say the cause was evidently a deficiency in the system, and that RFF and SNCF are trying to pass the buck to the individuals concerned.

I'm not sure whether that "signal cleared" is an agreed fact, but the rest of this looks like a knee-jerk CGT response in such a case.

http://florent.brisou.pagesperso-orange.fr/FicheToulouse-Dax.pdf (http://florent.brisou.pagesperso-orange.fr/FicheToulouse-Dax.pdf) confirms that Pau - Lacq has BAL signalling.

From SNCF (http://www.sncf.com/fr/presse/fil-info/TGV-TER-lescar-112241).
SNCF now say the false green signal was caused by rats nibbling the insulation off wires in a lineside cabinet. (For some reason the pictures in that report don't include the one just shown on TV news, of the nibbled wires in closeup.)