Thameslink Core pantograph strike

[dub]

ETCS has a function to lower pantographs (if implemented).

According this thread from the last time this happened it's meant to be linked to the balises to automatically drop the pan

Thameslink ‘Core’ major disruption (04/04)

I’ve just arrived at London St. Pancras to see all Thameslink trains at a standstill, due to overhead wires damage between St. Pancras and London Blackfriars. Thameslink services starting to queue up on the MML, heading into London now, too. Picture from Twitter appears to show damaged...

www.railforums.co.uk

 

[jdp30]

Was this an in service train, or one coming out of the siding south of Farringdon? Believe the pan dropping is handled automatically at Farringdon, so usually this happens when a driver is coming out of the siding and forgets they have to do it manually.

 

[Peter Mugridge]

Was this an in service train, or one coming out of the siding south of Farringdon? Believe the pan dropping is handled automatically at Farringdon, so usually this happens when a driver is coming out of the siding and forgets they have to do it manually.

It was an ecs from Kentish Town to Sevenoaks.

Sorry to be a pedant, but neutral section isn't the right term here. A neutral section is provided to prevent a phase-to-phase fault due to the train's pantograph bridging the gap between two separate electrical feeds which are out of phase. I think what you're thinking of is a de-energised run-off, where the pan runs onto a dead section of contact wire, the height of which gradually increases until the pantograph overheights and is lowered back into the pan well (this is not the same as an auto drop device (ADD) activation which detects damage to pantograph carbons).

Thank you; I knew there was something not quite right with the phraseology but I couldn't think what it was!

 

[Samzino]

According this thread from the last time this happened it's meant to be linked to the balises to automatically drop the pan

Thameslink ‘Core’ major disruption (04/04)

I’ve just arrived at London St. Pancras to see all Thameslink trains at a standstill, due to overhead wires damage between St. Pancras and London Blackfriars. Thameslink services starting to queue up on the MML, heading into London now, too. Picture from Twitter appears to show damaged...

www.railforums.co.uk

The only issue is what is the fail safe if the auto fails.

 

[AM9]

Are the trains not collecting third rail power when this happens, otherwise they would stop on the incline before the pantograph strikes anything anyway?

I was assuming that switching over to DC drops the pantograph anyway, just like happens at Farringdon, (intentionally). Or is it possible for the train to be driven with the pantograph up anywhere over 3rd rail?

 

[haltendehand]

Correct - I am suggesting a long neutral section from the end of the present overheads into the full length of Blackfriars station for the sole purpose of preventing any defective or forgotten pantograph from rising and striking the buildings between City and Blackfriars.

If one does happen, it would be visually obvious to any staff in the form of a raised pantograph at Blackfriars and if it still isn't spotted and the driver alerted at that point, any continued raising would happen beyond the station and hopefully the automatic drop detection would have time to react before it hit any of the signal gantries beyond the station.

On this occasion, the pantograph seems to have struck the office building that bridges the railway - which, ironically, is occupied by RDG and part of Network Rail. So proceeding all the way to Blackfriars before checking would seem to be impossible.

 

[Deepgreen]

I was assuming that switching over to DC drops the pantograph anyway, just like happens at Farringdon, (intentionally). Or is it possible for the train to be driven with the pantograph up anywhere over 3rd rail?

Given that the OHLE monitoring lights on the carriage roofs stay on everywhere, I imagine the pantos can be raised too (only joking!).

 

[Supercoss]

The dual voltage section from Farringdon platform to City Thameslink has Southbound trains arrive with pans raised and pick up shoes in contact with conductor rail ,
Northbound a train arrives at City Thameslink with shoes in contact with conductor rail , the pan is then raised but as the shoegear is non retractable the train continues on AC mode with shoes still in contact with 3rd rail until it departs Farringdon where conductor rail ends .

Original plan is if you can not change AC to DC train empties out then shunts forward over crossover near Smithfield and returns North on AC
-
if you can not change DC to AC you either empty out at city Thameslink Then either return south on DC or shunt into Smithfield sidings on DC.

Aside of failing to lower pantograph southbound a few Northbound trains have failed to change over and departed Farringdon on DC mode only to loose power in Clerkenwell Tunnels

 

[Somewhere]

ETCS has a function to lower pantographs (if implemented).

It obviously doesn't work, then!

 

[Samzino]

It obviously doesn't work, then!

Note in brackets he did say "if implemented" assuming this isn't some form of satire.

 

[Somewhere]

Note in brackets he did say "if implemented" assuming this isn't some form of satire.

Perhaps it ought to be implemented!

 

[Samzino]

Perhaps it ought to be implemented!

Agreed, however they'd still need a backup fail safe for when that fails. Hence why it will need to be implemented with a redundancy feature mostly physical.

 

[ComUtoR]

I was assuming that switching over to DC drops the pantograph anyway, just like happens at Farringdon, (intentionally). Or is it possible for the train to be driven with the pantograph up anywhere over 3rd rail?

You can raise the pant manually anywhere you want. What will happen is that the pan will raise till it goes 'over-height' and it will drop automatically.

The only issue is what is the fail safe if the auto fails.

The Human

In any case; what most likely happened here is that the Human failed first. The 'Auto'matic system still needs the Human squishy bit to make a decision and then trigger the 'Auto'matic system.


The pictures don't look that bad compared to previous incidents.

 

[Elecman]

Sorry to be a pedant, but neutral section isn't the right term here. A neutral section is provided to prevent a phase-to-phase fault due to the train's pantograph bridging the gap between two separate electrical feeds which are out of phase. I think what you're thinking of is a de-energised run-off, where the pan runs onto a dead section of contact wire, the height of which gradually increases until the pantograph overheights and is lowered back into the pan well (this is not the same as an auto drop device (ADD) activation which detects damage to pantograph carbons).

What is meant I think is a permanently earthed section of OLE after a Beau trap section which can raise at a suitable point. Tina point where the overheight detection on the pan operates and drops the pan automatically

 

[Samzino]

You can raise the pant manually anywhere you want. What will happen is that the pan will raise till it goes 'over-height' and it will drop automatically.




The Human

In any case; what most likely happened here is that the Human failed first. The 'Auto'matic system still needs the Human squishy bit to make a decision and then trigger the 'Auto'matic system.


The pictures don't look that bad compared to previous incidents.

Problem is the Human seems to be a factor regularly in these incidents so they can't be the only fail safe anymore.

 

[Supercoss]

signage exists at Farringdon and city Thameslink ( pictured) on both platforms , the ' end of wire' is at far end where daylight is
you could install APC magnets here at south end of city Thameslink platform but that would just cut power not cause pan to lower
APCo Balise now these are gaining popularity to force pan to lower May be better .to remove human factors issues
I wonder if train was being driven manually or was it in ATO / ETCS mode as it only came from Kentish Town ?

 

[TUC]

Always the same with the rail industry. Now even the pantographs are on strike ...

 

[ComUtoR]

APCo Balise now these are gaining popularity to force pan to lower May be better .to remove human factors issues
I wonder if train was being driven manually or was it in ATO / ETCS mode as it only came from Kentish Town ?

The balise will trigger the auto changeover.

Unfortunately, the Human needs to trigger the balise AND still set the train up correctly for auto mode.

 

[bahnause]

Note in brackets he did say "if implemented" assuming this isn't some form of satire.

No satire, tons of options and national values in ETCS you can use, not use or abuse.

 

[Robski_]

I notice on RTT that the train allegedly failed to stop at either Farringdon and City Thameslink. On TrackIT, the reporting messages for arrival and departure at both locations were within seconds of each other, also indicating that the train did not stop. I'm fairly sure the class 700 does not support doing a power changeover on the move - as when City Thameslink is shut, northbound trains still have to stop to change power modes before continuing to Farringdon. Happy to be corrected though.

 

[OscarH]

No satire, tons of options and national values in ETCS you can use, not use or abuse.

Given this is the UK rail industry, it'll be lots and lots of abuse I'm sure

 

[aem7ac]

What about a shunt resistor like on the Great Northern 313s and 717s? So signals are held at red at changeover points until the pantograph is dropped?

 

[43096]

I notice on RTT that the train allegedly failed to stop at either Farringdon and City Thameslink. On TrackIT, the reporting messages for arrival and departure at both locations were within seconds of each other, also indicating that the train did not stop. I'm fairly sure the class 700 does not support doing a power changeover on the move - as when City Thameslink is shut, northbound trains still have to stop to change power modes before continuing to Farringdon. Happy to be corrected though.

The fact it was an ECS working is a contributory factor - driver may well have been thinking he had no stops as it was empty, but that over-rode the need to change systems. Easy to mistake to make, in those circumstances.

 

[class717]

I notice on RTT that the train allegedly failed to stop at either Farringdon and City Thameslink. On TrackIT, the reporting messages for arrival and departure at both locations were within seconds of each other, also indicating that the train did not stop. I'm fairly sure the class 700 does not support doing a power changeover on the move - as when City Thameslink is shut, northbound trains still have to stop to change power modes before continuing to Farringdon. Happy to be corrected though.

This is right. Train did not stop at all through the core.

 

[Bald Rick]

Given the number of times this has happened now, would it not be an idea to put a neutral section of the overhead in as far as Blackfriars?

Granted, that wouldn't completely stop something being struck further down but the risk would be much lessened as, once clear of the roof at Blackfriars, it's some way to the first signal gantry and at the relatively slow speed from starting away wouldn't the automatic drop detection have a greater chance of kicking in before any damage is done?

How rarely is "it happens rarely" given that we seem to have something like this reported every few months?

I think this is the third or fourth time with a 700 - ie in the last 7 years. IIRC all the other incidents have been trains exiting the sidings just north of City TL.

One thing I should ask - how far south of Blackfriars is the first signal gantry that a pantograph could foul should the issue not be spotted at Blackfriars, and could it easily be protected against a strike?

As you’ve found out yourself - about 20 metres.

Putting OLE through Blackfriars - even unenergised, is a non trivial piece of work.


The design of the system is such that the train automatically drops the pantograph, but this can be overriden by the driver. Something odd about this one, and I suspect that someone is having a no tea no biscuits conversation tomorrow.

 

[Samzino]

The fact it was an ECS working is a contributory factor - driver may well have been thinking he had no stops as it was empty, but that over-rode the need to change systems. Easy to mistake to make, in those circumstances.

This would make the most sense considering that the driver would possibly have been in a mode of autonomy and just forgot indeed that although they're not a stopper they still indeed need to stop for that power change over.

But then again one would question why didn't the safety system in place regardless still catch this error and assuming it did then was it overridden? That will be a big question.

I'm wondering how hard it would be to integrate a TPWS similar emergency break application if you pass a magnet etc. at the point of bounds where the Pan should be down. Of course it would require detecting if the Pan is Up in some form sensor wise plus if that Pan is drawing any energy as the two comparators for a positive detection.

 

[800301]

Just throwing it out there, are we sure this was because the Pan was not dropped/power changeover commenced? And not a fault with with the Pan itself? Ie flipped over, not seated correctly?

 

[class717]

Just throwing it out there, are we sure this was because the Pan was not dropped/power changeover commenced? And not a fault with with the Pan itself? Ie flipped over, not seated correctly?

The pan was not dropped. The train didn’t stop at either City TL or Farringdon so no auto changeover commenced.

 

[Nicholas Lewis]

The pan was not dropped. The train didn’t stop at either City TL or Farringdon so no auto changeover commenced.

Was it an 8 car? Surprised it got so far up the incline after losing traction supply.

Also surely they need to have a standing rule that even ECS have to stop at Farringdon to do a changeover

 

[Bald Rick]

Also surely they need to have a standing rule that even ECS have to stop at Farringdon to do a changeover

There is!