378 De-Pantographed at Olympia

[Bald Rick]

So - does my idea of a physical inverted ramp fixed to the underside of bridges to 'catch' and guide downwards raised pantographs under the bridge (rather than the bridge simply hitting and destroying it) have any merit? I would have thought it would be a cheap and fool-proof (through being a fixed physical rather than systems item) means of saving at least significant damage, to the extent that trains could still continue in service after an encounter.

It would need to be a long ramp - ie long enough so that at linespeed a pan would be forced down at a rate it can cope with. Likely to be at least 50 metres long.

And then you'd need another ramp at the next bridge, and then the next, and the next...

Surely better just to have a system on the train that drops the pan when DC power is selected.

 

[Islineclear3_1]

Surely better just to have a system on the train that drops the pan when DC power is selected.

And a driver's reminder device at the changeover point if there isn't one already?

 

[Deepgreen]

It would need to be a long ramp - ie long enough so that at linespeed a pan would be forced down at a rate it can cope with. Likely to be at least 50 metres long.

And then you'd need another ramp at the next bridge, and then the next, and the next...

Surely better just to have a system on the train that drops the pan when DC power is selected.

If it's 50 metres then forget it (I'm not familiar with the maximum lowering rate achievable), but I would imagine the first one should be enough to trigger a warning for the driver or automatic lowering meaning that only the first bridge need be fitted.
If the system you mention is affordable and can be done in a sensible time - even better. I imagine the full cost of pantograph strikes must be pretty high - the disruption costs plus repairs to both train and infrastructure.

 

[notadriver]

The changeover is done on the move. To my knowledge this is the only location this takes place on a regular basis.

 

[rebmcr]

If it's 50 metres then forget it (I'm not familiar with the maximum lowering rate achievable), but I would imagine the first one should be enough to trigger a warning for the driver or automatic lowering meaning that only the first bridge need be fitted.
If the system you mention is affordable and can be done in a sensible time - even better. I imagine the full cost of pantograph strikes must be pretty high - the disruption costs plus repairs to both train and infrastructure.

You could have it only on the first bridge, and include a small spike to rupture the carbon and trigger the ADD. Furthermore, these would only be required in locations where the first bridge is close enough to the changeover to out-speed the overheight sensor.

 

[ComUtoR]

You could have it only on the first bridge, and include a small spike to rupture the carbon and trigger the ADD. Furthermore, these would only be required in locations where the first bridge is close enough to the changeover to out-speed the overheight sensor.

Once you've successfully managed to damage the pantograph. How do you get it back up an back into service.

Might as well have smashed it into the bridge rather than engineer a system to deliberately break it.

 

[tsr]

Might as well have smashed it into the bridge rather than engineer a system to deliberately break it.

To be fair there are plenty of safety systems on the network which are engineered so that you/a mechanical device deliberately breaks something, to sacrifice it for the greater good of network operations or give a reaction to an event which should only be carried out as a last resort.

This applies to all sorts of things ranging from derailer devices to egress handles. I'm not saying it's ideal, but a controlled, predictable piece of damage in an emergency is probably far preferable to unpredictable levels of damage requiring bespoke repair and recovery.

 

[Deepgreen]

Once you've successfully managed to damage the pantograph. How do you get it back up an back into service.

Might as well have smashed it into the bridge rather than engineer a system to deliberately break it.

Can't agree with this - a managed element of damage which would allow the train to continue in service on DC supply and then to a siding for enough repair to allow it to return to depot is better than a catastrophic failure requiring a service suspension to deal with (as happened yesterday), not to mention the cost of repair - a new pantograph vs. a small element replaced. All this, of course, should be a last resort after driver/system interventions have failed.

 

[aleggatta]

Surely some sort of alarm could be put in place at the end of the OHL, triggering signals to Danger and forcing the driver to contact the signaler? However it does seem strange to have happened, Electrostar changeovers seem to be pretty fool proof (not being able to have the pan raised with DC select) so I would suspect a fault occurred one way or another.

 

[Class 170101]

Good question, given that although southbound changeovers normally take place at Farrngdon, the wires now terminate just south of City Thameslink...

Thameslink has OLE as far as City Thameslink as should the pan drop not be working the unit can be sent back north all using the OLE power supply.

 

[Bald Rick]

Can't agree with this - a managed element of damage which would allow the train to continue in service on DC supply and then to a siding for enough repair to allow it to return to depot is better than a catastrophic failure requiring a service suspension to deal with (as happened yesterday), not to mention the cost of repair - a new pantograph vs. a small element replaced. All this, of course, should be a last resort after driver/system interventions have failed.

It doesn't cost that much, and it happens only about once or twice a year. It would cost a lot more to install some bespoke system (with all necessary design, technical and safety approvals).

 

[ComUtoR]

Can't agree with this - a managed element of damage which would allow the train to continue in service on DC supply and then to a siding for enough repair to allow it to return to depot is better than a catastrophic failure requiring a service suspension to deal with (as happened yesterday), not to mention the cost of repair - a new pantograph vs. a small element replaced. All this, of course, should be a last resort after driver/system interventions have failed.

The cost is not just about replacement parts or direct repair. Your taking a unit out of service. That has a cost to the TOC. I would also be concerned that without a pantograph the unit may get stranded. There may be no opportunity to return the unit to depot as your then stuck on DC.

I do see the point with small damage vs large but your still creating more problems rather than resolving any. Shouldn't the solutions start with the premise that incident should be prevented rather than mitigated.

 

[Deepgreen]

The cost is not just about replacement parts or direct repair. Your taking a unit out of service. That has a cost to the TOC. I would also be concerned that without a pantograph the unit may get stranded. There may be no opportunity to return the unit to depot as your then stuck on DC.

I do see the point with small damage vs large but your still creating more problems rather than resolving any. Shouldn't the solutions start with the premise that incident should be prevented rather than mitigated.

Couldn't agree more, but after all this time of AC/DC switching, it still happens too often, so that doesn't seem to have worked. If instructions don't address the problem, then perhaps a physical solution is needed. Or just live with the events when they occur and hope they remain non-injuring.

Incidentally, I wonder if the risk of damaged pantographs falling off onto passengers on platforms has been accounted for - yes, I know it's a tiny risk, but so are a host of others on the railway which have mitigation measures in place.

 

[ComUtoR]

Just like everything else on the railway it is deemed an acceptable level of risk and the cost to implement anything is higher than the cost to replace the pantograph.

The number of times it happens is insignificant. Our last one (that I'm aware of) was a unit going into Smithfield. A move that is unusual and not regularly done since the new wires went up. They implemented a new procedure and its never happened since.

No engineering solutions required, almost zero cost.

 

[Deepgreen]

Bald Rick's view is somewhat different : "A regular occurrence, and the pans almost always come to grief on the Westway Bridge. Every incident I am aware of there has been due to the driver forgetting to drop the pan, and I'd be surprised if this wasn't."

However, obviously, if procedural changes can fix the problem then that is the answer, but some would say that the problem remains significant.

 

[swt_passenger]

Thameslink has OLE as far as City Thameslink as should the pan drop not be working the unit can be sent back north all using the OLE power supply.

Thanks, I know about all that but didn't want to include yet another discussion of the way the northbound and southbound routines differ since a couple of years ago...

 

[ComUtoR]

Bald Rick's view is somewhat different : "A regular occurrence, and the pans almost always come to grief on the Westway Bridge. Every incident I am aware of there has been due to the driver forgetting to drop the pan, and I'd be surprised if this wasn't."

All due respect to the man with the cunning plan... Think of it in terms of how many trains go through the procedure every single day. We have a constant battle over things like this where we say "its a regular occurrence" and in terms of incident it happens often and new policies and procedures get implemented and people get disciplined. The other side of that is the view that statistically when you look at the big picture it becomes insignificant.

 

[Pumbaa]

Quite. In the grand scheme of things, it is uncommon. Normally has isolated consequences and doesn't result in wider failures.

Appropriate mitigation may well be a bigger sign.

 

[Bald Rick]

Of course the incidents on the WLL only really started to become regular (albeit not at all frequent) when LOROL started dong the changeover on the move. This was done partly to speed journeys, and partly to avoid a previous issue where drivers would release the doors at the changeover point.

One safety and performance issue solved, another one emerges. I would argue that overall risk has reduced though.

 

[redbutton]

a previous issue where drivers would release the doors at the changeover point

Are 378s like 377s in the way that the SDO system will refuse to release the doors outside of GPS-defined station limits?

If so, then the doors would only actually release if the driver goes through the whole emergency release procedure, which seems unlikely.

Perhaps in the light of these pantograph collision incidents LOROL should explore going back to the old changeover procedure and live with the slight risk of an attempted door release.

 

[Skoodle]

Are 378s like 377s in the way that the SDO system will refuse to release the doors outside of GPS-defined station limits?

They do. With the new SDO/CSDE equipment, you can't accidentally release the doors when not at a station.

 

[Bald Rick]

They do. With the new SDO/CSDE equipment, you can't accidentally release the doors when not at a station.

Correct, but this wasn't the case previously. Hence the provision of signs and Mitre Bridge advising drivers not to release the doors (not sure if they are still there for Southern?)

 

[redbutton]

(not sure if they are still there for Southern?)

I don't sign it so I couldn't say.

 

[43096]

Bald Rick's view is somewhat different : "A regular occurrence, and the pans almost always come to grief on the Westway Bridge. Every incident I am aware of there has been due to the driver forgetting to drop the pan, and I'd be surprised if this wasn't."



However, obviously, if procedural changes can fix the problem then that is the answer, but some would say that the problem remains significant.

How is "regular" defined? Daily? Weekly? Monthly?

Putting yet another system in place is not the answer: the railway costs enough to run without adding yet more cost and complexity.

 

[redbutton]

How is "regular" defined? Daily? Weekly? Monthly?

Putting yet another system in place is not the answer: the railway costs enough to run without adding yet more cost and complexity.

But that's how safety works in transport industries. Incidents happen, we learn from them, then put processes in place to minimize the risk of recurrence.

All those "costly" and "complex" procedures are the main reason there hasn't been a fatal accident (excluding level crossing and platform incidents) in over a decade.

 

[edwin_m]

It's a question of proportionality, aka the ALARP principle. Losing a pantograph may be regular but it's probably not particularly frequent, causing operational disruption but relatively low likelihood/severity of safety consequences. Any system to operate the pan automatically could itself be subject to false alarms or problems that cause the train to be stuck without power.

Anyway, I think we established some pages back that ERTMS includes a function to raise/lower pan, so if such a system is needed that sounds like the best way to provide it.