...is non-feasible on LHCS.
LHCS? please
...is non-feasible on LHCS.
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 Good job they haven't been replaced by untrained non-safety critical staff.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?
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.
Technically nothing was actually isolated by the sounds of things. If it was the angle cocks between the loco and first coach that were closed, that is normal. This is before we get onto the subject of a 42 wagon freight train running with the same braking system. Bearing in mind, if the loco was running light engine, the brake pipe angle cock would have to be closed to maintain a brake, a flashing light on the desk would be irrelevant. What if you had a ten coach train and the angle cocks between the 3rd and 4th coaches were closed? Would you have a system to identify that issue?However override and isolator actions should be designed to be egregious so that it is highly unlikely they could be enabled by accident or would escape detection if they were.
For example a giant flashing beacon on the driver's desk saying that part of the brake system has been isolated.
Do train drivers follow checklists like pilots? If so, how rigorously are they followed? I know in aviation there's a lot of attention on making sure checklists are followed attentively and not just lazily run through without positively checking each item.
The driver had no control of the train brake, so it was de-facto isolated.Technically nothing was actually isolated by the sounds of things.
The relevant vehicle would know that something was coupled to the autocoupler but that for whatever reason the brake isolating valve had been left in the closed condition.If it was the angle cocks between the loco and first coach that were closed, that is normal. This is before we get onto the subject of a 42 wagon freight train running with the same braking system. Bearing in mind, if the loco was running light engine, the brake pipe angle cock would have to be closed to maintain a brake, a flashing light on the desk would be irrelevant. What if you had a ten coach train and the angle cocks between the 3rd and 4th coaches were closed? Would you have a system to identify that issue?
I see why this incident would worry people (and rightly so) but the concept of a continuous brake via use of a continuous brake pipe throughout the train is old school tried and tested technology. Provided everything is done correctly (train preparation, brake continuity test and running brake test once the train is on the move) then it is an extremely safe system. Clearly something badly wrong went on here that will become clearer once the RAIB have concluded their investigation but I don't believe it will show deficiencies in the principal of conventional brake pipes.
Do train drivers follow checklists like pilots? If so, how rigorously are they followed?
What do you mean by checklists ? I have to perform a 'cab setup' and I have to follow certain 'rules' and 'procedures' If I was coupling a unit, there are a few safety checks that are required and must be carried out.
Also, should say that I'm in no way implying that train drivers don't do this sort of thing, I have no idea. Just curious.
Also not sure why freight train technology is relevant here.
There is no reason freight train equipment should affect the design of passenger equipment just because it happens to be loco hauled!
That depends on your definition.It is not "freight train technology". Its basic railway technology....the same technology that has been used for years on the WCML, ECML, GEML and any other area that uses or used LHCS.
Don't they use this technology? Isn't it just 2-pipe air brake, but with the coupler making the connections? As for 4TCs and all the other Southern (or SR stock) wasn't it the Electro-Pneumatic Brake, i.e. just substituting a wire for the brake pipe- for quicker response from the back of the train?That depends on your definition. Because 4TCs could be defined as LHCS and they didn't use it.
And just because it has been used for years does not mean it should be used here.
The vast majority of passenger operations in the UK do not use this technology.
Why was it selected here?
They already changed the coupling from traditional railway practice.
Was it that quick, considering the train went through the station and 650m beyond?Lucky the guard kept their head and acted quickly when they realised something was wrong, by the sound of it.
I am not sure about all multiple units, but Sprinters (and thus Pacers) only have a reservoir pipe through the formation. All braking is controlled electrically.Don't they use this technology? Isn't it just 2-pipe air brake, but with the coupler making the connections?
Wired systems are much more amenable to self checking than pneumatic systems like this.As for 4TCs and all the other Southern (or SR stock) wasn't it the Electro-Pneumatic Brake, i.e. just substituting a wire for the brake pipe- for quicker response from the back of the train?
Was it that quick, considering the train went through the station and 650m beyond?
I was interpretingI am not sure about all multiple units, but Sprinters (and thus Pacers) only have a reservoir pipe through the formation. All braking is controlled electrically. (Apparently the same for Electrostars as well)
as meaning LHCS. You are right, we do have a mainly D- and E-MU railway nowadays, but for parallels with MkV coaches I automatically thought of HST Mk 3 coaches and Mk 4s.The vast majority of passenger operations in the UK do not use this technology.
My understanding is the train passed through the Waverley at around 40mph..At what speed was the train traveling and where was the Guard relative to where the brakes were activated ?
a) don't know yet (but obviously not very fast if it stopped in 600 metres after the guard realised the problem, and b) the RAIB statement saysAt what speed was the train traveling and where was the Guard relative to where the brakes were activated ?
so it sounds as though each coach might have an emergency brake valve as well as (or instead of) just a passcom to the traincrew.The train was brought to a stand by the operation of an emergency device in one of the coaches by the Train Manager, which caused the train brakes to apply.
Could a single (set of) closed valve(s) stop a HST application though?You are right, we do have a mainly D- and E-MU railway nowadays, but for parallels with MkV coaches I automatically thought of HST Mk 3 coaches and Mk 4s.
On a HST, it would be unlikely to happen, as the brake would be applied after the brake test, before pulling away, so if there were isolated cocks, the rear power car would have vented the brake pipe down to whatever level the Driver had demanded, but then wouldn’t recharge the BP to release the brake.Could a single (set of) closed valve(s) stop a HST application though?
Wouldn't the MU jumpers send the brake signal to the other end of the train and then that power car would vent the isolated portion of the brake pipe?
(Does a DVT vent the local brake pipe based on TDM instructions from the locomotive and vice-versa?)
On a HST, it would be unlikely to happen, as the brake would be applied after the brake test, before pulling away, so if there were isolated cocks, the rear power car would have vented the brake pipe down to whatever level the Driver had demanded, but then wouldn’t recharge the BP to release the brake.
The BP is charged by the brake control unit, only the leading power car charges the BP, but both vent it.Does the compressor on the rear power car not recharge the brake pipe?
After all the rear power car will have a brakes released signal from the MU system.
I thought the formulation of that phrase by the RAIB was interesting. I wouldn't mind betting that what the RAIB mean is that the guard tripped an emergency door opener, as others have stated or suggested, as opposed to pressing the passcom which doesn't do the necessary.the RAIB statement says "The train was brought to a stand by the operation of an emergency device in one of the coaches by the Train Manager, which caused the train brakes to apply." so it sounds as though each coach might have an emergency brake valve as well as (or instead of) just a passcom to the traincrew.
The reason I referred to freight trains is because the vast majority of conventional air braked trains in this country are freight. Passenger services braked in that manner are in the minority. So I would find it strange to equip the small majority with your wonderful, expensive safety system yet not equip the (up to 5000 tonne) freight trains that pootle about on the same network. If what you've suggested should be made standard, it would be likely (I would have thought) that the same system would be strongly recommended to be fitted to freight train vehicles.The driver had no control of the train brake, so it was de-facto isolated.
The relevant vehicle would know that something was coupled to the autocoupler but that for whatever reason the brake isolating valve had been left in the closed condition.
This combination would trigger a system that used a continuity wire to show that the brake was continuous down the train.
Also not sure why freight train technology is relevant here.
There is no reason freight train equipment should affect the design of passenger equipment just because it happens to be loco hauled!
"Provided everything is done correctly" is a terrible thing to use as the basis for your safety case.
Administrative controls are the least reliable kind.
There is no reason this technology should have been used on a brand new self contained rolling stock fleet.
Surely the same arguments I always hear about why we can't have a standardised multiple working system for all trains equally apply here, why enforce compatibility with a freight rolling stock fleet to which it will effectively never come into contact?