What happens to trains during emergency switch off?

[Rana12345]

If there is an emergency switch off, what happens to the trains that are already in motion?

 

[12LDA28C]

If there is an emergency switch off, what happens to the trains that are already in motion?

Could you be more specific? Do you mean an emergency switch off of power supply / traction current, on AC or DC lines?

 

[Rana12345]

Could you be more specific? Do you mean an emergency switch off of power supply / traction current, on AC or DC lines?

On DC lines

 

[Supercoss]

Depending on speed, DC traction will continue until air pressure drops ( through compressors not running) or gradient naturally slows train. Faster you are going further you can coast

 

[swt_passenger]

I think I read on here that DC emergency isolations can be very difficult to apply because the trains act as pretty long “shorting straps” or jump leads, if they happen to come to rest across a planned break?

 

[Surreytraveller]

Normally, the signaller will be aware an emergency switch off is going to take place, and usually trains will have been brought to a stand, in stations where possible, before the switch off is taken.
Depending on the circumstances, the switch off will be delayed to get trains into platforms, with wrong direction moves or emergency permissive working if necessary.

 

[12LDA28C]

On DC lines

Of course not all trains that traverse DC lines are electric. Presumably diesel traction would continue until being checked by signals (unless contacted by the signaller or control) although on the LU a diesel train driver would be required to stop if they encountered a Gap Indicator lit.

 

[matt_world2004]

Some of them have batteries to provide emergency lighting and in some cases air con

 

[Trainguy34]

Depending on the circumstances, the switch off will be delayed to get trains into platforms

IIRC If they can't get to a platform, I think they would get another train in and get a train to train evac done or wrong line working to get it to a previous Station.

 

[800301]

On an Electrostar as soon as traction current is lost, you will lose all traction power, you will still have lights and air conditioning briefly but the unit will go into load shedding mode shutting down various different systems of the train to preserve battery life, and depending on how good they are depends how long you get, I was in a 8 car 387 a few weeks back and the overheads tripped out, the rear unit almost immediately went into full load shed but the front unit had a lot more life left in it, ultimately if the power is going to be off for sometime you have to Aux the unit off which is essentially a full shut down or when the power does come back on the train won’t have enough power to actually be able to switch back on

 

[jfowkes]

What is the procedure for drivers if traction power is lost?
Assuming you are in motion and signalling allows you to proceed, do you coast for as long as possible? Immediately come to a stop? Something else?

 

[800301]

What is the procedure for drivers if traction power is lost?
Assuming you are in motion and signalling allows you to proceed, do you coast for as long as possible? Immediately come to a stop? Something else?

Could be different at other TOC’s but depending on formation and where the Pans are located and their own policy’s but the rule book states for a loss of line light which is what would happen if the power went off;

“If the line light goes out and you have made one attempt to reset, which was not successful, and either of the following applies.

• The only pantograph in use is not on one of the first three vehicles.
• There is more than one pantograph in use on the train.”

“You must

• operate the pantograph down button, if you are driving a train with a pantograph in the raised position
• stop the train immediately
• report the incident to the signaller.”

If you are for example driving a 4 car 387 you which the Pan would either be in the 2nd or 3rd vehicle you can coast to the nearest station providing signals allow, it would also be advisable to contact the signaller while on the move to advise them, this might not be the case at other TOC’s

There are other situations where different rules apply if for example you see someone near the OLE or damage to the OLE

 

[12LDA28C]

Could be different at other TOC’s but depending on formation and where the Pans are located and their own policy’s but the rule book states for a loss of line light which is what would happen if the power went off;

“If the line light goes out and you have made one attempt to reset, which was not successful, and either of the following applies.

• The only pantograph in use is not on one of the first three vehicles.
• There is more than one pantograph in use on the train.”

“You must

• operate the pantograph down button, if you are driving a train with a pantograph in the raised position
• stop the train immediately
• report the incident to the signaller.”

If you are for example driving a 4 car 387 you which the Pan would either be in the 2nd or 3rd vehicle you can coast to the nearest station providing signals allow, it would also be advisable to contact the signaller while on the move to advise them, this might not be the case at other TOC’s

There are other situations where different rules apply if for example you see someone near the OLE or damage to the OLE

That's great information but the OP specifically asked about DC traction.

 

[najaB]

Assuming you are in motion and signalling allows you to proceed, do you coast for as long as possible? Immediately come to a stop? Something else?

I believe that, all things considered, drivers would to coast in an attempt to reach the next station.

There was a case a few years back where a driver managed to coast all the way from Bushey to Euston (https://www.standard.co.uk/news/lon...london-euston-after-a-power-cut-a3748781.html).

 

[12LDA28C]

I believe that, all things considered, drivers would to coast in an attempt to reach the next station.

There was a case a few years back where a driver managed to coast all the way from Bushey to Euston (https://www.standard.co.uk/news/lon...london-euston-after-a-power-cut-a3748781.html).

Apart from on the LU if an illuminated Rail Gap Indicator is encountered.

 

[ASharpe]

I was on a crush loaded 333 a couple of years ago that coasted from Kirkstall to the through line between 11 and 12 at Leeds. Another 100 yards and we would be mostly platformed. I could only laugh. The driver and signaler must have tried so hard to make it happen.

 

[Elecman]

Normally, the signaller will be aware an emergency switch off is going to take place, and usually trains will have been brought to a stand, in stations where possible, before the switch off is taken.
Depending on the circumstances, the switch off will be delayed to get trains into platforms, with wrong direction moves or emergency permissive working if necessary.

Depends on the need for the emergency switch off, someone in contact with the live supply then the switch off is immediately that the ECR gets advised

 

[zwk500]

Depends on the need for the emergency switch off, someone in contact with the live supply then the switch off is immediately that the ECR gets advised

And of course there's any number of situations where the breaker might trip without ECR being able to do very much.

 

[Elecman]

And of course there's any number of situations where the breaker might trip without ECR being able to do very much.

Indeed but they will try and reset it twice

 

[Meerkat]

Indeed but they will try and reset it twice

Isn’t that potentially rather dangerous for those at/near the cause of the problem?

 

[Elecman]

Isn’t that potentially rather dangerous for those at/near the cause of the problem?

There is a deliberate time delay before realising the breakers to give time for an Emergency call

 

[Meerkat]

There is a deliberate time delay before realising the breakers to give time for an Emergency call

What if it doesn't involve railway staff though, maybe at a station or level crossing?
The public are more likely to be less wary and think “well it’s stopped sparking, it must be off now”.

 

[najaB]

Isn’t that potentially rather dangerous for those at/near the cause of the problem?

Given that there is no meaningful difference between the fault current and that drawn by a couple of EMUs accelerating hard, it's more likely that a trip is a false positive than an actual danger condition.

 

[Surreytraveller]

What if it doesn't involve railway staff though, maybe at a station or level crossing?
The public are more likely to be less wary and think “well it’s stopped sparking, it must be off now”.

I don't think the public would give that any consideration. And there's a gap in the conductor rail at level crossings

 

[edwin_m]

Given that there is no meaningful difference between the fault current and that drawn by a couple of EMUs accelerating hard, it's more likely that a trip is a false positive than an actual danger condition.

Noting that this is a DC thread, but to be clear for anyone reading this post without that context, it applies to third rail DC but not to 25kV. The higher voltage means a very high current flows through a short circuit, way more than that drawn by several trains in normal operation.

 

[Meerkat]

I don't think the public would give that any consideration. And there's a gap in the conductor rail at level crossings

I may well be misunderstanding the physics but I was thinking if someone fell on the 3rd rail, and when someone might think it’s safe to move them.

 

[Falcon1200]

Having only worked with 25kV OLE and never third rail, what kind of area is affected when an emergency switch off is imposed on the latter? (With OLE it is often a huge area, far greater than outsiders might expect).

 

[Annetts key]

I may well be misunderstanding the physics but I was thinking if someone fell on the 3rd rail, and when someone might think it’s safe to move them.

It’s made very clear to railway staff that you don’t put your own life at risk. You wait until you have confirmation that the third rail (or indeed the OLE) is safe before helping any injured person.

 

[Surreytraveller]

It’s made very clear to railway staff that you don’t put your own life at risk. You wait until you have confirmation that the third rail (or indeed the OLE) is safe before helping any injured person.

Railway staff who have PTS training. I don't think it's mentioned to others