Procedure for loss of interlock

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najaB

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Currently on 1F90 1453 Scarborough to Liverpool Lime Street and we're crawling along at c. 20-30mph. There was a 'could a member of staff...' intercom message and the guard went and checked the doors in carriage 'A', though we're still crawling along.

I'm assuming the driver got a loss of interlock warning, which prompted the intercom message to check the doors.

Is the procedure to proceed at a safe speed to the next booked calling point, or to the next station as we've passed one without stopping?

Thanks.

Edit: As I was typing we sped back up! Still curious about the procedure though.
 
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trentside

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I'd imagine that a loss of interlock would've initiated a full service brake application.

Could it possibly be a pass on operation instead?
 
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Loss of interlock would trigger a full brake application until the relevant switches were worked to isolate it. Sounds more like a passcom to me but I'm not sure on those units, was the guard checking the doors or are passcoms fitted in the doorways on those units?
 

HLE

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Passcom overrided by the driver by the sounds of it. I'm guessing this was a newer DMU?

Older units just dump the air.
 

IKB

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Loss of interlock would trigger a full brake application until the relevant switches were worked to isolate it. Sounds more like a passcom to me but I'm not sure on those units, was the guard checking the doors or are passcoms fitted in the doorways on those units?

Depends on the age of the rolling stock though, no? Not sure what units operate on that line.

Don't know about other stock, but on an Electrostar if someone pulls an egress the driver can override the brake application by depressing a foot plunger in order to coast to a stop in a safer place (max 80 second override).
For a 'Pass Comm' on the same stock the brake application can be overridden by depressing the same plunger without any time limit. If the passenger can be spoken to via intercom or via the guard then no requirement to stop. The rule book only mentions stopping 'immediately' if the train is leaving a station or if you have reason to believe the train is in danger.
 

najaB

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Sounds more like a passcom to me but I'm not sure on those units, was the guard checking the doors or are passcoms fitted in the doorways on those units?
Not sure, but he specifically said "Can I check those doors please?" to the guy who was standing near it. Maybe he leant on the passcomm.

This was a Class 185, by the way - I'm scared of their doors at the best of times!
 

driver9000

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185 passcom handles are notoriously sensitive and leaning against one can be enough to sound the alarm. The Driver can override it and I reckon the Guard was looking for the one that needed resetting or checking to see it hadn't been disturbed.

The PIS message asking a member of staff to answer the intercom is triggered if the cab to cab isn't answered.
 
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Matt Taylor

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I believe that in the event of a loss of interlock the driver has to operate the TIS (Traction Interlock Switch) and then manually check that all doors are secure before detraining at the next suitable location.
 

TheEdge

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Wont have been a loss of interlock, that would have triggered a full brake application. Much more likely a passcom and the guard checking each door as they go past.
 
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Depends on the age of the rolling stock though, no? Not sure what units operate on that line

Yes it does, however excluding Chiltern's bubble cars all DMU stock on UK rails has interlock.

That's assuming the pacers do, they must, but then again they are pacers......
 

IKB

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Yes it does, however excluding Chiltern's bubble cars all DMU stock on UK rails has interlock.

That's assuming the pacers do, they must, but then again they are pacers......

I wasn't referring to existence of interlock per se (every service train has that now AFAIK) but an immediate brake application on losing it. On more modern units you will lose traction power, but an emergency brake application can be overridden on certain stock.
 
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I wasn't referring to existence of interlock per se (every service train has that now AFAIK) but an immediate brake application on losing it. On more modern units you will lose traction power, but an emergency brake application can be overridden on certain stock.

You're definitely right when it comes to passcoms, my understanding with traction interlock was that it always bought on an immediate brake application until isolated for the train to move again.

Which units are you thinking of would be good to get it clarified?
 

IKB

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You're definitely right when it comes to passcoms, my understanding with traction interlock was that it always bought on an immediate brake application until isolated for the train to move again.

Which units are you thinking of would be good to get it clarified?

My understanding of Electrostars (375/377/387) is that during an egress activation the override mushroom will bypass the emergency brake application (provided it is depressed within 3-6 seconds) and hold the door shut (albeit with a small gap) for a maximum of 80 seconds until the driver stops the train or it is below 4mph, whichever is sooner. (obviously you cannot take power until reset).

Even on a 455 an egress activation will break interlock(and thus power) but the brakes won't come on.
 
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My understanding of Electrostars (375/377/387) is that during an egress activation the override mushroom will bypass the emergency brake application (provided it is depressed within 3-6 seconds) and hold the door shut (albeit with a small gap) for a maximum of 80 seconds until the driver stops the train or it is below 4mph, whichever is sooner.

Even on a 455 an egress activation will break interlock(and thus power) but the brakes won't come on.

Yes now you mention it, I think the turbostars are the same as their cousins, I'll have to drag the manual out.....
 

tsr

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Yes now you mention it, I think the turbostars are the same as their cousins, I'll have to drag the manual out.....

171s are the same. With the override pressed, there is an 80 second maximum delay to the doors becoming freely openable, during which the driver must try to find a suitable place to stop, and make an announcement in the mean time that passengers should keep clear of the doors. The train will then come to a stand and the doors will be able to be opened under 4mph.

Erm, in theory... I've never, ever heard of it going that smoothly in practice. The last two occasions I've heard of, the trains came to a grinding halt on the Fast lines out of London Bridge, and it was discovered interlock was actually lost due to power faults. Cue much moving of passengers, securing doors, TIS, and back to the depot via the next location for de-training...
 

tsr

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Smoothly in practice o/

Indeed ;) It's good that you don't get too many passcoms or interlock/egress issues on the 171s...

I think quite a few of the regular pax on those are now clued up enough to realise that it's a bad idea to use such things outside of a dire emergency. I've even had major fights kicking off on those units, doors not opening, suspicious behaviour and so on, and passengers simply won't push the alarm. They know they'll have to sit in the middle of nowhere for ages while someone goes to reset it*, because it makes the same noise as giving the driver "1" on the buzzer, and so they often shove the brakes on, or don't react to the opportunity to override in time. Similar problems with driver reactions and delays apply to the egress, but it's also hidden behind a "break glass" panel, which means when you lose interlock, it's usually down to a power fault meaning the unit itself can't maintain it, or a dodgy door locking component.

*usually a very annoyed Norwood driver or Selhurst conductor, and meeting either of those does not make the best customer experience on the railways!
 
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