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Braking issue on Caledonian Sleeper causes train to "run away" at Edinburgh
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It's been a fascinating thread to read, mainly because I don't think I've ever seen so many well intentioned but slightly baffling posts using half understood knowledge of train brake systems. I guess that's not a subject that interests many enthusiasts which is probably understandable. I've also learned some things too about passenger stock I'm not familiar with.
Just for accuracy, I'm not aware of any current container flats that are not single piped. As has already been said on freight wagons the yellow main reservoir pipe is only ever used for auxiliary things such as opening discharge doors etc.
Single piped wagons don't run out of air under any kind of normal braking and are not limited in any way in terms of how often you can apply and release the brakes. The limitation is in how long you have to wait for the brakes to fully release throughout the consist before adding power again. Obviously in situations such as hill starts you do apply power against brake but generally try to avoid it otherwise.
A brake test is performed after remarshalling a train, with certain exceptions, and in some other specific situations without overcomplicating things. It shows brake pipe continuity throughout the train by trapping air in the brake pipe, this then being released from the rear (normally) It checks the brakes on the last vehicle apply and release as they should, which proves continuity. The brake pipe is then overcharged to equalise the distributors. This will show nearly all of the issues that could have caused this incident so likely either the brake test was not carried out correctly or the integrity of the brake pipe was not maintained after the brake test was carried out.
Just for accuracy, I'm not aware of any current container flats that are not single piped. As has already been said on freight wagons the yellow main reservoir pipe is only ever used for auxiliary things such as opening discharge doors etc.
Single piped wagons don't run out of air under any kind of normal braking and are not limited in any way in terms of how often you can apply and release the brakes. The limitation is in how long you have to wait for the brakes to fully release throughout the consist before adding power again. Obviously in situations such as hill starts you do apply power against brake but generally try to avoid it otherwise.
A brake test is performed after remarshalling a train, with certain exceptions, and in some other specific situations without overcomplicating things. It shows brake pipe continuity throughout the train by trapping air in the brake pipe, this then being released from the rear (normally) It checks the brakes on the last vehicle apply and release as they should, which proves continuity. The brake pipe is then overcharged to equalise the distributors. This will show nearly all of the issues that could have caused this incident so likely either the brake test was not carried out correctly or the integrity of the brake pipe was not maintained after the brake test was carried out.
EE Andy b1
Established Member
The brake pipe cock was accidentally knocked and isolated the air trapped in the brake pipe after the brake test when other cables were being attached, hence brakes released, train moved off, running brake test done, train slowed by dynamic brake on loco. Next event was a runaway, no train brake as isolated from Class 92, loco brake only, until guard realised it was a runaway operated the shunting lever and released the air trapped in the brake pipe and train eventually came to a stop.
43096
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So are the cocks not latched in the same way as a standard air brake pipe is? If so, it sounds rather like the incident at Darlington four decades ago.
EE Andy b1
Established Member
Yes they are latched on the Class 92 bufferbeam but you then have them pipes coupled to the dellner coupler. If you look at that photo I posted on #70 you can see. I don't know if there are other isolating cocks on the dellner, can't tell.
43096
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Sorry, I wasn’t clear - I was referring to the pipes attached to the Dellner, rather than the standard air pipes.
swt_passenger
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Perhaps you can’t (or don’t want to) supply the overall train’s hotel services through the coupler head, or you want to limit the modifications to the locos. AIUI when a pair of EMUs or DMUs are coupled it’s only control and indication circuits that pass through the head, there’s nothing that you’d call high powered.
Crikey haven't seen those for a long long time. W you're sat patiently waiting for 30+ wagons worth of reservoirs to fill up from empty you do wish you still had the old system two pipe system though...
I can understand the ETS being required to be a seperate jumper, but the auxiliary/comms jumper could have been put on the coupler face
BRX
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If the isolating cock can be knocked accidentally during the coupling procedure then to me it would seem the problem is either or both of
(a) the continuity test being carried out before all the coupling/connecting is completed and there is no longer a risk of the lever being moved
(b) a design that makes it possible for the lever to be moved unintentionally.
(a) the continuity test being carried out before all the coupling/connecting is completed and there is no longer a risk of the lever being moved
(b) a design that makes it possible for the lever to be moved unintentionally.
High Dyke
Established Member
I believe someone stated BBC News as the source. Then again just last week during the hot weather a passenger on a train stranded at Peterborough was quoted as saying the air-con failed when they turned the engines off. Poor reporting of the fact that the electric wires were down and therefore no train supply...but the media and seemingly others don't understand that!
It's given me a chuckle to pass a Sunday afternoon turn.
It would seem to me if this is the case that there is a design defect in the brake pipe cock - whether its fitted to the loco or vehicle, my experience of 'standard' brake pipe cocks is that they are self-venting, so for this scenario to pan out both cocks would have to have been shut.
Sleeperwaking
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Dellners
EE Andy b1
Established Member
I agree normally coupling brake pipe to brake pipe and leaving one isolating cock shut and one open, the air from the brake pipe would vent!
I don't know myself how it works on Mk5s via the dellner coupler, not a normal configuration for loco hauled stock.
The truth will out! as they say.
Bassman
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Irrespective of the speculation documented here of the technical and/or protocol issues which caused this event.
As a lay passenger it remains clear to me that the sleeper, appears to have run without a failsafe procedure for splitting the train. This failure has happened with potential dangerous consequences. It has happened within a relatively small number of working experiences (one failure of safety out of perhaps 100 times the new train has been split, which is a significant occurrence in probability terms!) .
It seems the scoping of failsafe procedures has not been thought through comprehensibly beforehand. If it was, then the incident would not have happened.
No matter the reassurances of learning from mistakes, unfortunately there are major implications of damage to reputation of trust and safety . Especially with another emergency braking incidence in recent history.
I am thankful this problem has come out before train splitting and new coaches were let out on the highlander. Is it safe to do so?
The problem now is increasingly reputational and perhaps becoming potentially more political rather than technical.
I can speculate that the reasons are within the franchising and bidding system itself.
As a lay passenger it remains clear to me that the sleeper, appears to have run without a failsafe procedure for splitting the train. This failure has happened with potential dangerous consequences. It has happened within a relatively small number of working experiences (one failure of safety out of perhaps 100 times the new train has been split, which is a significant occurrence in probability terms!) .
It seems the scoping of failsafe procedures has not been thought through comprehensibly beforehand. If it was, then the incident would not have happened.
No matter the reassurances of learning from mistakes, unfortunately there are major implications of damage to reputation of trust and safety . Especially with another emergency braking incidence in recent history.
I am thankful this problem has come out before train splitting and new coaches were let out on the highlander. Is it safe to do so?
The problem now is increasingly reputational and perhaps becoming potentially more political rather than technical.
I can speculate that the reasons are within the franchising and bidding system itself.
kingqueen
Member
It's still not down as an incident under investigation on the RAIB website.
kingqueen
Member
I guess, but the fact we now (presumably) know what occurred generally wouldn't stop a RAIB investigation. They are generally very good at looking at the further underling causes that resulted in a situation, and I would normally expect them to be particularly interested where were it but for luck and quick thinking / action by signaller, driver and guard, this could have been a very significant crash.
TractiveEffort
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If there is a definitive cause and plan to deal with it, I am not sure what the RAIB could add, I have seen quite a few incidents over the years that they walk away from, when there is one and only one cause, that can be addressed by the company concerned.
RAIB have published an update today and are carrying out an investigation:
Nice to have some clarity over exactly what happened as well!
Nice to have some clarity over exactly what happened as well!
JonathanP
Member
No system can ever be "failsafe" in the sense that it can never fail. When the term "failsafe" is used in a railway environment, it means that in the event of an unexpected occurrence(power failure, air leak), it will fail in a "safe" way.
Railway Systems are generally designed with the expectation they are operated by trained professionals, so overrides and isolators are available, whilst consumer equipment might simply stop working in the event of a fault. If rolling stock was designed so that the braking system was impossible to isolate, then in the event of a fault with the braking system, the only way to get it back to a depot would be to lift it off the track with a crane.
Surreytraveller
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Which is effectively what happened on Friday with all the 700s North of the Thames, with the drivers unable to reset the trains themselves.
swt_passenger
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Overtaken by publication now, but these initial RAIB statements often do take around a fortnight to appear. Lack of an early update on their website isn’t at all unusual.
Surreytraveller
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Yes. Good job they haven't been replaced by untrained non-safety critical staff. I wonder if doing away with guards has been considered as part of the introduction of the new stock?
Bletchleyite
Veteran Member
I doubt it - complications like this (and the driver being unable to access any part of the train without walking along the ballast, I guess?) would mean DOO is non-feasible on LHCS.
Having said that, the Germans and Swiss do.
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