OHLE damage

[Grumpy Git]

There seems to be a lot of OHLE damage of late and this weekends episode at Wembley cannot be put-down to adverse weather.

Is there evidence of more failures of OHLE (maybe due to more 25kv train diagrams) or are they being reported more often (i.e. more likely to be in the mainstream news)?

 

[GRALISTAIR]

I am not an expert but with a busier than ever network that has to mean more wear and tear. Now add in (and I am not sure of my facts here) more trains using multiple pantographs, then surely that has to have an affect. Now, as you repair a line, do you replace the whole wire length (which is definitely more robust - single tension lengths are always better) - or do you splice it. I suggest for a quick repair splicing will be done. However, I maintain that a splice must remain a weak point. Complex mix of factors. Now also as the network has got busier and busier, then an incident has far greater impact and gets reported on the news. Now factor in social media and twitter and instant news and you have the recipe for what we see.

My 2 pen'north

 

[Bald Rick]

The month of near constant strong winds will unquestionably have had an effect:

1) causing the wires and supporting equipment to move around more, causing more wear on the flexible components

2) causing more airborne debris to come into contact with the OLE, potentially causing minor damage (unseen) and introducing new points of weakness

3) causing routine maintenance to be deferred due to restrictions working at height in high winds.


Having said that, I don’t think OLE issues have been particularly more prevalent of late.

 

[ChiefPlanner]

I have nothing but admiration for how the NR teams have had to deal with incidents of late - remember the South Kenton problem has involved so far 3 long overnight possessions and complex works - (think of the effort to block 4 AC lines and the 2 adjacent DC lines) - with attendant earthing and so on , the personal logistics concerned , let alone the equipment and repair works. Seems there is another long night coming up for further remedial works.

Not forgetting the TOC impacts - apart from the passenger car etc issues - but rebalancing the stock , crew etc impacts and no doubt the need to get displaced sets back into their carefully programmed maintenance cycles.

And , lest we not forget , freight.

Hard railway work all round.

Bad enough picking up wind driven tree etc debris - in a domestic garden - imagine what is involved in removing similar debris from pantograph wells (in my day we had dedicated unsung heroes in the form of rolling stock technicians who used to check these areas for tree debris both on depot examinations , and in service by doing eye of sight checks during their normal work)

About the worst dewirement I can recall - was at Wembley Central where a ground warming sheet in the allotments adjacent to the DC lines - was airlifted towards the AC lines - got wrapped around a passing class 87 - wrecking the pan at about 90 mph , bringing the OLE down , the arcing set fire to said plastic sheet , which landed on some badly secured signal troughing - and burn through the signalling cables - effectively knocking out all 4 lines for a while from Harlesden Junction to at least North Wembley. Truly a terrible peak - and we had a 2 track railway for 48 hours , - but the DC , as ever saved us from worse. Whenever we had a bad peak - we used to recall this one , which pretty well trumped most incidents. About 8000 delay mins from an "external" impact.

 

[O L Leigh]

There seems to be a lot of OHLE damage of late and this weekends episode at Wembley cannot be put-down to adverse weather.

Is there evidence of more failures of OHLE (maybe due to more 25kv train diagrams) or are they being reported more often (i.e. more likely to be in the mainstream news)?

I think you're hearing more about them because they're happening on main arterial routes like the WCML where they cause a large amount of disruption. Getting them into the mainstream media is one way of alerting travellers who may be intending the use the affected route.

 

[Belperpete]

I think you're hearing more about them because they're happening on main arterial routes like the WCML where they cause a large amount of disruption. Getting them into the mainstream media is one way of alerting travellers who may be intending the use the affected route.

So why do we so rarely hear about similarly disruptive incidents in DC areas? All lines out of Waterloo shut would disrupt far more people than all lines out of Euston shut, for example.

 

[Bald Rick]

So why do we so rarely hear about similarly disruptive incidents in DC areas? All lines out of Waterloo shut would disrupt far more people than all lines out of Euston shut, for example.

Because the disruption is, usually, smaller. But it happens a LOT more often. At least daily.

 

[ComUtoR]

Because the disruption is, usually, smaller. But it happens a LOT more often. At least daily.

You drive me crazy sometimes... I'm hooked.

I live in 3rd rail land and rarely find disruption due to 3rd rail issues. Could this be because 3rd rail problems are causal in track circuit issues or because they are quickly resolved ?

OHLE tends to be severe and takes a *long time to resolve. I was caught up in the cable fire the other night but that was signalling and not DC. I can barely remember when I was caught up in a DC issue. Yet OHLE issues I can recall quite a few.

Confirmation bias ?

 

[Bald Rick]

You drive me crazy sometimes... I'm hooked.

I live in 3rd rail land and rarely find disruption due to 3rd rail issues. Could this be because 3rd rail problems are causal in track circuit issues or because they are quickly resolved ?

OHLE tends to be severe and takes a *long time to resolve. I was caught up in the cable fire the other night but that was signalling and not DC. I can barely remember when I was caught up in a DC issue. Yet OHLE issues I can recall quite a few.

Confirmation bias ?

Most D.C. issues manifest themselves as one of three things:

1) fires, which are actually bits of the D.C. kit burning (there was one yesterday) - but usually reported as a lineside fire,
2) track circuit failures due to the D.C. bonding failing - the root cause is a failure of the D.C. system and not a signalling failure (happens all the time; I’d guess that between a third and half of track circuit failures in D.C. land are caused by this) - usually reported as a signal failure
3) loss of power in specific electrical sections caused by distribution failure (also happened yesterday) - usually described as a power failure. (There is, of course, much more distribution kit to go wrong on D.C. railways, and it does!)

What can also happen is 3rd rail joints burning out, or failing - we had one of those last week - but I’d say that only happens once a month or so.

On top of that, Third Rail makes lots of other incidents worse than they would be if OLE was provided instead - any form of person on the track, any obstruction on the line, flooding, snow or frozen rain. And it makes maintenance of the track a lot more expensive.

For OLE, there are plenty of failure types which cause little to no disruption. Droppers off above contact wire, broken (or missing) return conductor; even some fairly serious faults can be got around with coasting, which is not something easily done with third rail.

 

[ComUtoR]

Most D.C. issues manifest themselves as one of three things:

Cheers and again, I find it a matter of different perspectives. From my perspective I see DC issues as those directly affecting the DC current; those appear to be quite rare. But when on AC (I miss those days) I consider AC issues to be where wires are down or something is caught in the knitting.

On top of that, Third Rail makes lots of other incidents worse than they would be if OLE was provided instead - any form of person on the track, any obstruction on the line, flooding, snow or frozen rain. And it makes maintenance of the track a lot more expensive.

Very true but when wires come down, you tend to get the entire lines restricted. If you get DC issues you can generally run with a line open and you just cruise past it. The cable fire the other night kept the slow lines open but I have found; anecdotally; that wires down or AC issues will destroy the service for a wider geographic area and kill all lines.

even some fairly serious faults can be got around with coasting, which is not something easily done with third rail.

The concern with 3rd rail has always been with bridging the circuit. I can coast just as well under DC as I can with AC.

 

[Bald Rick]

Cheers and again, I find it a matter of different perspectives. From my perspective I see DC issues as those directly affecting the DC current; those appear to be quite rare. But when on AC (I miss those days) I consider AC issues to be where wires are down or something is caught in the knitting.



Very true but when wires come down, you tend to get the entire lines restricted. If you get DC issues you can generally run with a line open and you just cruise past it. The cable fire the other night kept the slow lines open but I have found; anecdotally; that wires down or AC issues will destroy the service for a wider geographic area and kill all lines.



The concern with 3rd rail has always been with bridging the circuit. I can coast just as well under DC as I can with AC.

Not arguing with any of that; except that when the OLE comes down it is not often that all lines are closed. It does happen more often in headspan areas, but only if the headspan itself is damaged. It is, however, often the case that to put the wires back up you need adjacent lines closed, and that more often than not means all closed.

 

[ComUtoR]

Another School Day for me. The more educated I get the less I am sure which is better. DC, anecdotally, has less onboard issues too. Shoe Gear issues are rare but Pantograph issues are numerous. :/

Cheers, as always, BR.

 

[Bald Rick]

Another School Day for me. The more educated I get the less I am sure which is better. DC, anecdotally, has less onboard issues too. Shoe Gear issues are rare but Pantograph issues are numerous. :/

Cheers, as always, BR.

Just to bounce this up again, in the last week or so there have been 3 incidents of displaced conductor rail causing service suspensions. Most recently yesterday at Haslemere.

 

[edwin_m]

You drive me crazy sometimes... I'm hooked.

I live in 3rd rail land and rarely find disruption due to 3rd rail issues. Could this be because 3rd rail problems are causal in track circuit issues or because they are quickly resolved ?

OHLE tends to be severe and takes a *long time to resolve. I was caught up in the cable fire the other night but that was signalling and not DC. I can barely remember when I was caught up in a DC issue. Yet OHLE issues I can recall quite a few.

Confirmation bias ?

The chaos at Lewisham a couple of years ago would not have happened if it had been electrified on the overhead system.

 

[GB]

The chaos at Lewisham a couple of years ago would not have happened if it had been electrified on the overhead system.

Perhaps if it was OLE there could have been a problem with that type of equipment resulting in the same situation.

 

[LesF]

Another School Day for me. The more educated I get the less I am sure which is better. DC, anecdotally, has less onboard issues too. Shoe Gear issues are rare but Pantograph issues are numerous. :/

Cheers, as always, BR.

There must be a reason why Network Rail proposed to convert the southern region DC to 25KV OLE. Though that's gone quiet since the GW electrification cost over 3x the budget.

 

[ComUtoR]

The chaos at Lewisham a couple of years ago would not have happened if it had been electrified on the overhead system.

Kentish Town was under the wires.

Lewisham wasn't really down to the 3rd rail. There was a list of categorical errors that led to the Lewisham Incident. 3rd rail was part of the cause and certainly kicked off a chain of events but so much more happened than 3rd rail problems. I get the impression that 3rd rail can exacerbate an issue and the risk to passengers is higher.

I suppose that both systems have their benefits and their problems.

 

[edwin_m]

Kentish Town was under the wires.

Lewisham wasn't really down to the 3rd rail. There was a list of categorical errors that led to the Lewisham Incident. 3rd rail was part of the cause and certainly kicked off a chain of events but so much more happened than 3rd rail problems. I get the impression that 3rd rail can exacerbate an issue and the risk to passengers is higher.

I suppose that both systems have their benefits and their problems.

It was ice on the third rail that stopped the first train and triggered the whole incident. And when people started leaving the trains the third rail had to be turned off, thus stranding more trains. Neither of those would have happened with OLE. Kentish Town was ultimately caused by foliage on the pantograph, presumably collected while travelling round the leafy southern suburbs in third rail mode, so would not have happened if the whole Thameslink route had OLE.