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Tube Trains Collide

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Investigation under way after Tube train collision


An investigation is under way after two of London Underground's (LU) new trains collided when the tracks moved.

The collision happened on the District Line between East Putney and Southfields stations and caused minor damage to carriages.

Manager Kevin Bootle said the two trains had been temporarily withdrawn from service during investigations.

A transport union said the incident highlighted "cuts to track inspections and maintenance."

...or highlights transport union members, responsible for maintaining and checking tracks, not doing their jobs properly.

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Tracks moved? Is this a stupid way of saying the points changed at the wrong time, or that they actually shifted (as will happen particularly on bends)? Still, no real harm done so I hope (but expect to be disappointed) that there won't be a load of crying, people wetting themselves, and loads of stupid, pathetic, paranoid, expensive "measures" put in place and instead there will just be an acceptance that sometimes shit happens.

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My point in the OP was that the union was quick to capitilise on the incident without considering the possibility that negligence by their members, rather than 'cutbacks' was the root of the problem.

An inquiry will I hope reveal the cuase of the accident.

While railwaymen may or may not be justified in striking to bring tube services to a standstill, I think they were a little too quick to deflect the blame in this case.

Riedquat, while you may be not concerned with rail safety, I am.

I prefer a service where the trains do move, and the rails don't.

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My uneducated guess is it's more likely this occurred due to inadequate rail checks than negligence. After all, rails don't look like the most complex pieces of equipment to check over. They either move or they don't. The rail system must take an enormous amount of constant maintenance thanks to it's age and workload. Cut back staff, check the lines a little less and this is what happens.....

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Riedquat, while you may be not concerned with rail safety, I am.

I prefer a service where the trains do move, and the rails don't.

There's being concerned with safety and then there's being overly obsessed with it.

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There's being concerned with safety and then there's being overly obsessed with it.

For a very long time, Britain built the world's railways. We even came up with a bizarre railway track width called a gauge, which we exported across the Empire and beyond.

By an ingenious set of calculations called "adding up feet and inches" great minds such as Brunel, Stephenson and their proteges came up with an amazing system whereby two trains of a certain width could pass each other on adjacent tracks, and not hit another! A truly astonishing intellectual achievement

The principle of operation is this: Train wheels are a defined distance apart (The aforesaid 'gauge'). Rails are set the same distance apart, for obvious reasons. Otherwise, the rails would be superfluous, and trains could be driven everywhere. We wouldn't want that, now, would we?

Having invented trains and tracks, the early railway engineers discovered a fundamental problem. You can successfully operate two trains, on the same track, running in opposite directions, as long as those directions do not result in the two trains heading towards each other. If that happened, (which it did, 50% of the time) they reached a point of proximity whereby neither train would successfully operate. Ever again.

They cracked this problem eventually by having parallel tracks so that the trains could pass each other.

In order to fit into tunnels, trains are a particular width, as are the tunnels (the tunnels are made slightly larger than the trains, for reasons that should be fairly obvious.) To be precise, I believe the trains came first, and then they came up with the idea of making the tunnels wider than the trains. That way, the trains would fit in the tunnels. There is a sort of fiendish logic to it.

Where two trains get close to each other, on parallel tracks, the principle is that the adjacent tracks are a certain minimum distance from each other. I.e. there should be a 'gap' between tracks, and consequently, between trains. This utilises the engineering theory that if you keep a 'gap' between objects, they will, by definition, not come into contact with each other.

This 'gap' concept may be difficult to grasp, but is essential to smooth operation of trains without crashing them into each other. One could say it is one of the more fundamental principles of operating vehicles comprising hundreds of tons of metal carrying hundreds of people at high speed, especially when converging from opposite directions. Many engineers would hold that these 'gaps' are rather important. Even more so, if you value human life.

It would seem that maintaining this 'gap' is beyond the monkeys who operate the London Underground, and more astonishing still, you do not appear to be disturbed by this revelation.

I deduce that you either have a death wish, or you do not use the London Underground.

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Look, things go wrong from time to time. Accept it. No-one was hurt, not a big incident. Railway tracks can shift a bit. You're blowing a minor incident out of proportion, and don't try to defend that with a load of "what ifs" unless you've got good reason to believe it's just pure luck that meant it wasn't more serious and wasn't just a good chunk of unlikely bad luck that caused this in the first place. Having a bit of a sense of proportion isn't having a death wish.

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Look, things go wrong from time to time. Accept it. No-one was hurt, not a big incident. Railway tracks can shift a bit. You're blowing a minor incident out of proportion, and don't try to defend that with a load of "what ifs" unless you've got good reason to believe it's just pure luck that meant it wasn't more serious and wasn't just a good chunk of unlikely bad luck that caused this in the first place. Having a bit of a sense of proportion isn't having a death wish.

:D Consider yourself trolled.

Though, more seriously, when trains collide, it's not 'bad luck'. It's something that should NEVER be tolerated on a railway.

I don't really think you have a death wish.

What I really think is that you work for London Underground. ;)

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Work for the London Underground? That would involve working in London - suggesting that really is trolling!

Trains can collide through bad luck. Track shifts (particularly on corners) unless it's fixed to something solid (will be in the tunnels, don't know enough about the Tube to know if this location is or not). That's the sort of thing maintenance really should deal with but it would very much depend upon the specific circumstances how bad that is. The other way I can think of is if a train has been stopped too close to points, so that there isn't room for another to pass (think of a train diverging from the main line but coming to a halt with the back not having moved forward enough to give enough clearance). I think that signalling should prevent that from happening on running lines but it might be possible in a yard, in which case it deserves a slap on the wrist for someone but that's about it.

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I'm with HR on this- it simply should not happen. TBH if the rails shifted so much that the trains were able to touch then it seems to me that it was very lucky that one of both of them did not derail. The consequences of the train on the inside of the bend derailing into the train on the outside could have been absolutely catastrophic.

It's not as if this is a recent problem. We know full well what happens when rails go out of gauge and trains derail.

http://en.wikipedia.org/wiki/Grayrigg_derailment

http://en.wikipedia.org/wiki/Hatfield_rail_crash

http://en.wikipedia.org/wiki/Bexley_derailment

etc.

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tracks can move in the vertical plane too.

Imagine a tight curve, and a subsidence occurs between the tracks...the inner train would sway into the outertrain, and vice versa...sufficient subsidence could cause a collision.

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Then there's the possibility of meteroites.

But one's man's 'luck' is another man's ignorance of what is inevitable if only you had known, another's probability of outcomes and yet another's chaos theory.

then there is the possibility that the subsidence was like on a sponge...the tracks fell, the trains hit, the scene is back to normal....call Clouseau!

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It's not as if this is a recent problem. We know full well what happens when rails go out of gauge and trains derail.

http://en.wikipedia.org/wiki/Grayrigg_derailment

http://en.wikipedia.org/wiki/Hatfield_rail_crash

http://en.wikipedia.org/wiki/Bexley_derailment

etc.

None of those sound like they're comparable with this (although the original article doesn't really contain any useful information. Grayrigg was point stretcher bars missing, Hatfield a broken rail, and Bexley bad track. The last of those is the most similar, but there's no information to say whether they're at all comparable either. None of those examples are about out of gauge track.

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None of those sound like they're comparable with this (although the original article doesn't really contain any useful information. Grayrigg was point stretcher bars missing, Hatfield a broken rail, and Bexley bad track. The last of those is the most similar, but there's no information to say whether they're at all comparable either. None of those examples are about out of gauge track.

So... what railway company do/did you work for then?

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So... what railway company do/did you work for then?

Never worked for any railway company. And I'm not trying to justify the fact that my model derails too often as being realistic either :)

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It's not like they're not constantly warning you to 'mind the gap'..

Is there a bigger gap between trains than the gap they actually warn you about?

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Never worked for any railway company. And I'm not trying to justify the fact that my model derails too often as being realistic either :)

I am now very concerned for the safety of the imaginary people who travel on your model trains, particularly as some of my relatives (Aunt and Uncle) are imaginary.

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Now we're talking about something you should be worried about. Fortunately the passengers are safe, since the doors don't actually open so they can't board the trains in order to get in any danger. A sensible precaution.

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