Great Heck

[ThinLizzy]

Hi
I've been on a ourse the last 2 days learning about the mechanical side of a 455 {third rail EMU, used on commutter services out of London}. One of the key points of the course was to check the position and condition of a bit called 'the life guard'. This is a metal rod that hangs down in front of the leading wheels of the unit, and will deflect most objects on the track that would otherwise go under the wheels.
The trainer kept refering to the Great Heck incident, and he seemed to think that the life guards should of smacked that land rover of the line.
I'd like to discuss this please.

[buffy500]

Personally I would have thought that a Land Rover is probably pushing it a bit !
A log or general debris maybe, but a friggin 2 ton car ? I doubt it somehow, think he is being a bit over hopeful of what it could do, certainly at that speed.

[wookey]

arn't they just there to knock small objects off the line, stones, bricks, dustbins, luggage trolly's etc. sorta thing?

i mean hell, that landrover? that would probably have smashed into the front of the train and lifted it off the rails before it even got as far as the
life guard things,
besides i think it would be a lot to ask of them to push a two ton vehicle off the line.

[southcoasttrains]

Missles, that should clear the way.

[Goingnorth]

Interesting accident Great Heck...I did see a report that the train wouldn't have derailed if it wasn't for Bogie straps...Maybe TL might like to explain this. The Lifeguards are really supposed to deflect smaller objects: Bricks, Stones, Logs that sort of thing...not so much cars...although bits of cars maybe.

The DVTs have 50 ton capacity deflector shields (In addition) on the front which under normal circumstances would have dealt with the Landover. The thing about Heck was the Landover was trapped at the site of the cutting, and the DVT ran over the motor block...derailing it slightly, then completely at the points. Only to be hit by an oncoming train. A very unlucky accident indeed...

[wookey]

mm,

very sad all the factors came together as they did,


ahh, i see why the front of the land rover was missing now,
i didnt realise the DVT actually ran over the engine block

[numnutz]

HI southcoasttrains I cannot see how hurling religious texts at an obstruction would clear it

[spartacus]

Dunno, some of 'em are pretty hefty!

[GavinW]

Life guards (which are fitted to 91's and DVT's) would not have prevented Great Heck.

I was at Haymarket in 1984 when the Polmont accident happened and the DBSO that hit the cattle was fitted with life guards and the DBSO still derailed. The DBSO's were fitted with "cowcatchers" after this (fitted behind the buffer beam, so not visible) to prevent the same thing happening again.

Not sure (as it has been 5 years since I worked on them) if the DVT's have similar fitted, but I think they do.

[ThinLizzy]

I have heard some nasty rumors about these DVT's and crashes. Ie they are not as heavy as a loco and so are more likely to ride up and over and object.
Bogie straps.
Yeah heard about some crash i didnt know about, in 1992? a slam door unit hit something, and the bogies got ripped off. Apparently this caused alot more injuries than if they had stayed on. Basically there is a massive metal bolt that is attached to the body, and slotted down through the bogie and then secured by a nut and a split pin to stop the nut becoming dangerously loose. But in this crash the bogies were just ripped straight off. Going by what Going North said, it might be a different design on a 91 set.
An example of what i mean happened to a 3 cop? At an un protected farm crossing down the south central network somewhere. This low loader got stuck on the crossing, and the train didnt know. The train hit it at full speed and the front bogie was ripped clean off.
Gtg to dinner, if you lot dont undertsand the above, say so and i will knock up a little diagram.

[mattvince]

Hi
I've been on a ourse the last 2 days learning about the mechanical side of a 455 {third rail EMU, used on commutter services out of London}. One of the key points of the course was to check the position and condition of a bit called 'the life guard'. This is a metal rod that hangs down in front of the leading wheels of the unit, and will deflect most objects on the track that would otherwise go under the wheels.
The trainer kept refering to the Great Heck incident, and he seemed to think that the life guards should of smacked that land rover of the line.
I'd like to discuss this please.

'Life Guards' are common on SR EMUs, as you probably know better than I. Whats on new DMUs and 25kV EMUs are 'object deflectors', big bumper-style things running across the width of the underframe in front of the leading bogie. The SR EMUs were exempt from having these, as it was assumed that with 3rd rails around, no dumb kid would dare put stuff on the tracks, lest they recieve a 'nasty shock' (pun intended). However, I think Electrostars and Desiros have them anyway, they are probably a part of the stucture.

As for Heck, my impression is that the DVT hit the LR side on, and almost exactly perpendicular (at a right angle). The size of the vehicle meant the DVT hit the LR with the buffers, rather than the air dam. Had it been a Eurostar set, the outcome might be different. Yes, the nose would probably be trashed, but the shape of it, and the protruding Sharfenburg (hidden under the doors) would have upset the balance, forcing the LR to one side and out of the alignment. The articulated design of the train would have kept the coaches in alignment. The big problem with Heck was the facing points, which put the derailed, but upright, DVT, into the 66s path. On Eurostar noses, there's a number of them lying around on North Pole, spares obviously.

[ThinLizzy]

Yeah, i got told off for calling 'object deflectors'.... 'cow catchers'.
I guess as alot of people said, a landrover isnt a common obstruction on a railway line, and there for you shouldnt expect trains to be able to deal with them.

[basildd]

Had it been a Eurostar set, the outcome might be different. Yes, the nose would probably be trashed, but the shape of it, and the protruding Sharfenburg (hidden under the doors) would have upset the balance, forcing the LR to one side and out of the alignment. On Eurostar noses, there's a number of them lying around on North Pole, spares obviously.

There was a southbound Eurostar set which passed that very point some 6 minutes before the incident, working a returning overnight test train on the ECML. The shape of the actual scharfenberg coupling wouldn't necessarily have pushed the vehicle aside - there is probably more risk of it having punctured the side of the vehicle and then dragged more of it in front with the bogie riding over the debris causing a more severe derailment (had the Plasmor sidings points not been where they were, it is highly likely that this accident would have been a minor derailment). The noses 'lying' around' at north Pole are castings made for such an eventuality, so that they are readily available rather than having to get one specially manufactured. It made sense at the time to use the existing tooling to make them.

As for the DVT weight, the vehicle actually has a concrete and steel slab built into the floor of the vehicle which is designed to provide the same sort of protective weight as a locomotive and was extensively tested at Washwood Heath for crash worthiness. Unfortunately you cannot legislate for every type of possible incident, especially as in Great Heck where a number of unrelated incidences came together to cause the tragic events.

Oh and as for the comments re slam door stock, it has nothing to do with bogie design and everything to do with coupling design. The reason that scharfenberg fitted trains are safer is that they are designed to stay in a straight line (such as happened with the 155mph Eurostar derailment south of Lille, which stayed on the track (apart from both power cars). The same with buckeye type couplings - the problem Steve was referring to was likely to be the Cannon Street accident where an EPB unit hit the buffer stops in a low speed collision, but the couplings used were not of the modern type, allowing the vehicles to come together and the design of the coaches meant that the body of one slid from the frame and into the body of the next vehicle, crushing it. This was remedied by the monocoque construction of modern stock which means there is a much reduced incidence of crush accidents and even where they are derailed at high speed (Potters Bar for example), they remain virtually intact.

[anamorph]

The thing is, as everyone has said, these accidents are one-offs that it is just not possible to protect against. Interestingly the two most horrifying, Polmont and Great Heck, were caused by outside factors (Vandalism and a car leaving the road - which in the case of Polmont, was a vandalized fence which allowed the cow on the line). Life guards, tho, have been fitted almost universally since the dawn of railways, but realistically they are only effective at low speeds. Above about 30-40 mph, forget it. Peppercorn Pacific "Saja Jirau", on an up special christmas parcels from Waverley to King's Cross in 1957 hit a turnout that had fell off a freight train. Since it was dark, it wasn't seen, until the train (a BIG engine with a 12 coach train) hit it at 60mph. The engine ended up upside down on the embankment facing Edinburgh - a complete somersault - so if an engine of that size travelling at 60 gets flipped, a 90 tonne diesel or electric doing a ton or more hasnt got a chance....

[ThinLizzy]

Dale, i only heard s hsort bit about this accident, so i dont know if its the one your talking of at Cannon Street. There was talk a few years ago, of fitting all slam door stock {class 400 southern emu's basically} with 'cup and coning' and to try this idea, 2 connex units had their couplings converted. i think it was scrapped A because of the cost, and B because you could only run 2 units joined together due to you not being able to corridor connection with the new couplings. Dale probably knows more on this.