'Split train' passengers rescued (BBC News)
 

Hundreds of rail passengers are led to safety after their train splits in two in a tunnel in south London.

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Well for once the Beeb didn't over-egg it, and admitted that it wasn't a safety issue. Makes a welcome change to see a sensible piece of reporting. :)

When a train divides there's always a long delay because you're not allowed to couple it back up until an RST (Rolling Stock Technician) has examined both trains. So the line is blocked whilst the bloke makes his way across Rush-Hour London in a van. At least now that the slam door stock has gone there's no jumper cables or air fittings to repair. On modern EMUs all normal services go through the junction boxes located underneath the couplers.

I don't know what stock it was, presumably 375 ? I do remember that a while ago Networkers went through a phase of coming apart. Connex changed the couple-up procedure by adding a 5 second push on-test to the existing 5 second pull-away test. It did the trick. (Of course they have crappy old tightlocks, whereas I believe the 375s have all been converted to Delners which are supposed to be far superior). Time will tell no doubt.

On BR if a brakepipe was disconnected or split the brakes would be applied automatically. Does this system not apply on modern stock.

As with all replies, the answer depends on the stock. ;)

If the train has a Brakepipe, then yes it will. So for loco hauled stock and multiple units like HSTs this is certainly true.

But modern EMUs don't have Brake Pipes. They tend to have Main Reservoir Pipes in conjunction with Electro-pneumatic brake systems. If a train divides, they will still have an Emergency Brake Application for a number of reasons.

Designers of modern trains often emulate the Brake Pipe concept with a "Brake Continuity Wire". This starts at the Auxilliary Supply (Battery) and runs round the train through all manner of safety switches till it gets to the desk in the leading cab. When you energise the desk by putting your key in, the electrical feed from this wire operates the motors and brakes on the train. If the wire is interrupted by the train dividing (or by any safety switch opening), the feed to the motors is cut and the brakes go into emergency, because the brake system is configured so that voltages keep the brakes OFF.

There's more to it than that, because several 'looped' safety systems are interrupted when a train divides, but they all have the same effect - they cause the brakes to come on.

HTH

Thanks HTH for the detailed information about different braking systems. It all seems a bit too complicated for me. As you get older the little grey cells get less and less.

Supposed to have been two "Networker" 4-car sets 465911 + 465914.

Oh right, they're the modified MetCams. The Networker coupling problem is supposed to be fixed.

I hope that the driver who put these 2 units together isn't going to get it in the neck for this. :eek:

networker nusence
 

this as happened a couple of times in my memory a couple of years ago fcc's class 365s decoupled while in motion then in the year's of the crappy connex this accured again then when in motion a southeastern class 465s 914/214 again split a couple of months ago,i think why dont they just update the networker couplers!
calum mclean 14:)

:confused: i meant numbers 465911&465214 sorry for schoolboy errors

This also happened to the 185's when they first started to appear.

Dumb question time. Is the driver aware that the train has split (and hence able to report it) and whats to stop the following train hitting whats been left behind as surely the signals team can't detect that it has split if the driver doesn't notice ?

There see I said it was dumb ;)

OK, there are 2 separate issues here. All modern trains are sprawling with safety systems, so something as major as the train coming apart will invoke an Emergency Brake Application *. If you read previous answers in this thread you'll find out about the Brake Continuity Wire on modern EMUs. Also Brake Piped trains like freight trains and HSTs will stop because the brake pipe pressure drops. Both halves of the train will come to a stand pretty smartish, and the Rulebook requires a driver to determine the cause ofany unsolicited brake application. So once he starts walking back down the train he'll notice that it has divided.

* It is possible to override this system to get a train moving again, but I won't go into details about this on a public forum, it might be useful to terrorists. :rolleyes:

With regard to signalling, because both parts of the train stop close to each other, there's a good chance that they'll be in the same signalling section. Additionally if it's track circuit block signalling then they'd show up wherever they are. Plus of course the driver is required to inform the signaller immediately when the train divides.

HTH

Ah, I see. So the leading unit with the driver will stop as well automatically. I had it in my mind that it would go barrelling onwards in blissful ignorance of having left something behind.:eek:

Thanks for that, very informative