Separate names with a comma.
Discussion in 'UK Railway Discussion' started by 87015, 1 Aug 2019.
Loco hauled coaching stock?
It would make absolutely no sense to dispense with guards on the new stock - it's loco hauled stock, for a start, hundreds of yards long and none of the conditions for safe self-dispatch of such long trains exist on the routes they run on.
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.
So something of a re-run of the Darlington run away I mentioned (I trot this out whenever possible as it is the only rail fact I even half remember). In my working life giving anaesthetics in the NHS we looked hard at our rare critical incidents (you will all be glad to hear). It was always several things going wrong at the same time - the holes in the slices of Swiss cheese lining up is how it was often spoken of. So this was a mistake in coupling the train, failure to do a brake continuity test, perhaps something causing the problem with the coupling of the train (fatigue, distraction, poor training - who knows), perhaps something causing the problem meaning the brake test was omitted or misinterpreted (fatigue, distraction, poor training - who knows). It is why no fault investigation and early briefing of anyone else who might be affected are so crucial.
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?
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? 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.
That is an excellent question. The answer to which, I suspect, is "no".
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?
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.
So I'm not a professional pilot, but to give an example from gliding, before each flight there is the pre-flight CBSIFTCBE checks:
Controls - full and free movement without interference
Ballast - weight of pilots, equipment and luggage is within aircraft limits. Any additional ballast is correctly and securely fitted.
Straps - tight and secure, all seats, even if unoccupied
Instruments - check for broken glass, reading zero or reading sensibly (to the extent that such checks are possible while on the ground and not moving)
Flaps - if fitted, check movement. If not fitted, positively confirm that you are flying an aircraft without flaps
Trim - full and free movement, puts pressure against stick. Set to takeoff position.
Canopy - down and locked, resists positive upward pressure.
Brakes - both airbrakes extend fully and equally, up and down, in control all the way. Locked closed after checks.
Eventualities (not called emergencies because this stuff will eventually happen to you) - plan what you will do in the event of a cable or rope break at each stage of the takeoff.
There are similar checks for each stage of flight. Pilots are encouraged to not just rattle through them, but actually check the thing. Touch each instrument when checking it, that sort of thing. A student pilot or someone on checks who is clearly just reciting the checks without really paying attention (even if the checks pass) would get called out for it.
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.
working from memory, when I was taught to prep 442's, there was something in the process where by we had to vent the brake from the other unit to confirm brake continuity (I only prepped a 442 once after being taught and it was years ago). surely to safeguard from this happening again a dump valve could be fitted in each coach with a air gauge, with the process being to drop the brake pipe pressure by say 1/2 bar from the rear coach and watch the pipe charge again?
Pretty much the same then.
A lot of what we do is regulated by some sort of rule or procedure. When I couple a unit there are specific checks I must carry out. When I prep a unit there are specific checks I need to carry out too.
Less so as you are driving but that too is regulated by driving policies or the rulebook. A 'running brake test' is specified in the rulebook and has been discussed in this thread already.
Depending on what unit you are driving, you can get warnings in the cab.
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.
That depends on your definition.
Weren't 4TC type formations fitted with EP brakes?
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.
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?
Was it that quick, considering the train went through the station and 650m beyond?
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.
(Apparently the same for Electrostars as well)
Wired systems are much more amenable to self checking than pneumatic systems like this.
The obvious solution would have been to wire the train through with TDM control and use those to control the brakes.
That has a "brake not isolated" channel built into the standard and requires only three wires using a pre-existing standard.
At what speed was the train traveling and where was the Guard relative to where the brakes were activated ?
I was interpreting
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.
My understanding is the train passed through the Waverley at around 40mph..
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 says
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.
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.
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.
The BP is charged by the brake control unit, only the leading power car charges the BP, but both vent it.
Just to clear up some points.
The sleeper arrives at Carstairs, then the Edinburgh loco goes on the back end. Then the train is split and the Glasgow portion departs.
The Glasgow portion does not need a brake test as the brake continuity has not been broken. As drivers on here know you build up the air and trap it then the shunter/guard destroys the air and should check the brakes are on. The air cock (red) is then closed and the driver builds his/her air back up.
The train 1B26 departs Carstairs at 0640 after the cross country service departs towards Edinburgh. As Carstairs is not on a gradient the driver would be sitting with just the engine brake on waiting on the signal.
In between the brake test and departing it looks like the air cocks have been closed between the engine and the coaches. So the brakes on the coaches are still off as the air has been built up and as they are brand new coaches there would be absolutely no leaks at all.
Driver sets off but there is absolutely nothing to tell him the cocks have been closed. By luck or bad luck he’s had proceeds all the way to Edinburgh and would only have realised something was up when he applied the brakes.
The fast acting guard / train manager, having realised something was up, would have pulled the passcom/brake valve releasing the air in the coaches, which brought the train to a stand.
Very very fortunate that this was not a disaster .
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 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.
'Provided everything is done correctly' isn't a terrible thing to use as part of a safety case. The whole industry runs on the basis that every worker should be competent and adhering to the correct rules and procedures. There are safety systems in place to mitigate against dangerous occurances yet these dangerous occurances still take place (as the number of incident reports on the RAIB website demonstrate).
This incident was dangerous and had the potential to be very serious indeed. However, events of this nature are relatively rare so although there will rightly be improvements abd recommendations brought about in the aftermath of this, there has to be a bit of realistic thinking about how much money the industry is prepared to spend to safeguard against a rare occurance which can be safeguarded against by other means.