Possible third rail electrifications

[najaB]

On AC it then has to go through transformers which lose up to 20% of the power before it goes into traction.

Any transformer that loses anything close to 20% of the input power is in serious need of replacement!

 

[A0]

No Poster can seriously claim that failed third rail is as disruptive as failed overhead. Yesterday & this morning Paddington was frozen by damaged overhead & 2 days before a lightening strike at Blisworth on the overheads on the WCML ruined services for 5 hours.
A Poster said he would find figures to prove third rail had more deaths than 25kv. He made his excuses and left,nothing provided.
Another Poster linked to a study showing DC used x% more kWh for the same work as AC. If you read the small print the study said it was power consumed at entry to the train,not into the motors. Totally unfair to DC,all the power goes to the motors to move the train. On AC it then has to go through transformers which lose up to 20% of the power before it goes into traction.
This no more DC attitude,using spurious arguments, means routes like ore to ashford,Uckfield to hurst green,Reigate to Guildford etc cannot be filled in.
So we have to use dated diesels. No one is advocating Third rail for anything more than fill ins. It can't deliver the power for more than about 100mph. But if the third rail is kept clear of ballast(at Paddington today I noticed NR had piled it right up to LUL's third rail from platform 14),it's economical & easily done & easy on the eye & what is wrong with that if it allows the railway to be more economic?

Your mixing two points -

1 - whether there should be an extension of 3rd rail
2 - the merits of AC versus DC

On 1 - there is a *clear* health & safety risk, no doubt. You cannot, with a straight face, claim that it is no less safe to have a live rail on the ground as opposed to 25kv wires 20' above your head.

Of the two "failures" you mention:

- the Paddington incident *appears* to be caused by passing a red signal. It will doubtless have damaged other infrastructure such as points. The only reason its affected the catenary is because of where it came off the rails. Frankly, I'd be more relieved it didn't cause a major accident, because let's be honest in most of our lifetimes there were two fairly serious incidents around there at least one of which was caused by passing a red signal.

- the lightning strike could so easily have taken out signalling equipment, which is a risk to all lines. Living in the area, I can tell you the storm which hit Northamptonshire / MK yesterday afternoon was quite huge - I've never before seen running water along a number of main roads in MK (that's despite commuting to MK for almost 15 years), yet I did yesterday, that's how big that storm was.

The AC vs DC debate is something quite different, because you could so easily have 3000v DC overhead. But there are pros and cons for each system. And given we've largely electrified at 25kv AC for the last 60 years, there would have to be an astoundingly good reason to change that to DC.

 

[najaB]

On AC it then has to go through transformers which lose up to 20% of the power before it goes into traction.

Any transformer that loses anything close to 20% of the input power is in serious need of replacement!

Plus, if your problem really is losses during AC to DC conversion, all you are doing is shifting the location of the loss from the locomotive to the trackside equipment.

 

[SpacePhoenix]

I doubt that 3rd rail would fair any better then overhead when it comes to lighting strikes

 

[najaB]

I doubt that 3rd rail would fair any better then overhead when it comes to lighting strikes

Indeed. Given that the most powerful bolts are upwards, lightning would cause a trip at the very least.

 

[Taunton]

the logical choice for what was then the Southern Region was third rail extension. H&S risks were hardly considered compared with today

I wonder what the H&S risk difference actually is. How many staff have been electrocuted in recent years on DC lines? The only RAIB report in recent times I recall on such an incident was on AC overhead near Runcorn, where the OHLE fell down.

Only today Paddington is paralysed, all 8 approach lines, because an overhead support was struck by a derailed train way over on one side of the layout. The support knocked down by a freight derailment on the North London Line not too long ago caused very lengthy disorganisation until replaced. When AC has an issue, the dislocation is out of all proportion to what it takes to fix comparable issues on DC.

 

[najaB]

I wonder what the H&S risk difference actually is.

Read the thread: it's been posted that the third-rail network contributes eight times the risk despite being less than half the size of the AC network.

 

[Taunton]

eight times the risk

I was looking for "actual" incidents rather than the "risk" of them. Unfortunately "Risk Assessment" has been completely corrupted in recent times by fictional assessments and figures plucked out of the air, invented to suit the agenda of the authors.

 

[najaB]

I was looking for "actual" incidents rather than the "risk" of them.

I don't know if that data is published anywhere, specifically breaking it down by OHLE v third-rail.

 

[Philip Phlopp]

I was looking for "actual" incidents rather than the "risk" of them. Unfortunately "Risk Assessment" has been completely corrupted in recent times by fictional assessments and figures plucked out of the air, invented to suit the agenda of the authors.

The only member of staff to die on the railways in the last two years died as a result of falling onto third rail. Non PTS trained though, for what it's worth - SWT cleaner who fell from the train onto the energized third rail.

The statistics for risk of electrocution being eight times higher comes from the number of staff who manage to electrocute themselves on the third rail and then report such an occurrence through their chain of command.

It's not magicked out of thin air, unlike some XDM's fantasy numbers concerning 25kV losses, which I can categorically state are totally wrong - all the power consumed by DC units going to the motors - just fantasy bollox.

 

[Bald Rick]

No Poster can seriously claim that failed third rail is as disruptive as failed overhead.

Those of us who work with it make that claim with some justification.

Yesterday - disruption on SE metro due to failed DC power distribution equipment.
Yesterday - disruption Clapham Jn as power switched off all lines on Southern side to deal with someone intent on doing harm (not reqd with OLE)

This stuff happens almost every day. I would report it, but we'd all get bored.
--- old post above --- --- new post below ---

Only today Paddington is paralysed, all 8 approach lines, because an overhead support was struck by a derailed train way over on one side of the layout.

Just three of the approach lines have been out of action today.

 

[Bevan Price]

Does anyone know the age & condition of the feeder stations & supply cables on the Merseyrail network, and when they are expected to need replacement ?

That is likely to be the point at which the future of 3rd rail will be given serious consideration. If big savings can be made by converting to OHLE, then that will probably happen for sections outside the tunnels. And if they can devise a way of using AC overhead conductor rails (rather than wires) inside the tunnels, that could see total conversion of the 3rd rail network.

 

[Taunton]

I wondered about that too, as I seem to remember Class 86 didn't have 6.25kV capability (maybe 81-85 didn't either?). Only the Stockport and Styal routes were originally electrified and barring the largest electric loco class from either would have been far too restrictive. I don't think electric freight could run on the GE until the 6.25kV was eliminated in the 80s.

Just to pick up these old points, reduced 6.25Kv was never installed on the West Coast, although it was originally proposed, and no 6.25Kv locomotives were ever built. Electric locos could indeed not have run on the GE until converted. The "25Kv" operation on the GE was in fact mostly at the reduced 6.25Kv, and the suburban units on the Shenfield, Southend, Enfield and Chingford etc lines hardly ever ran further out onto the full 25Kv.

Was Manchester - Crewe fully dieselised at electrification?

No, it changed over in 1959 directly from steam. It was before even the Class 40 locos were built in quantity.

some of the EMUs had a design shortfall that meant occasionally, they would not satisfactorily revert [from 6.25Kv] to the full serial 25kV configuration ... with spectacular catastrophic failures, usually involving a fire that destroyed the motor car.

This was one manufacturer's electrical equipment (not EE). No vehicles were destroyed, all were repaired, although one transformer explosion led to a passenger fatality in the adjacent saloon. Separately, the earlier 25Kv (only) locomotives did lose several over time to equipment fires.

 

[SpacePhoenix]

If the 3rd rail was struck by lightning would just the local substation trip or would a number of adjacent substations trip as well?

 

[Bald Rick]

If the 3rd rail was struck by lightning would just the local substation trip or would a number of adjacent substations trip as well?

Normally just the sub for the section affected. Depending how close the strike is, the effects can be rather dramatic.

*****
Edit:

Back to incidents caused by the third rail. Signalling failure London Bridge this morning, actually caused by a short between 3rd rail and running rail blowing track circuit fuses.

 

[Trog]

The statistics for risk of electrocution being eight times higher comes from the number of staff who manage to electrocute themselves on the third rail and then report such an occurrence through their chain of command.

Perhaps managers in AC areas are not supplied with ouija boards?

 

[Philip Phlopp]

Perhaps managers in AC areas are not supplied with ouija boards?

My dictionary says 'electrocute is to injure or kill someone by means of an electric shock'. It's from Oxford, they might change the definition when they get their own 25kV wires for GWR drivers to crash into.

 

[AM9]

Normally just the sub for the section affected. Depending how close the strike is, the effects can be rather dramatic.

It might any trains in the section a few problems also.

 

[snowball]

Here are some Glasgow details:

http://www.scot-rail.co.uk/page/electrification

http://homepages.enterprise.net/iainlogan/railway/gse1.html

The Glasgow North electric train services (The Blue Trains) came into service in November 1960, but after a disastrous series of transformer explosions, had to be temporarily withdrawn until the problems could be rectified. Services resumed again in November 1961.

 

[Philip Phlopp]

It might any trains in the section a few problems also.

It'll blow the fuses on the shoe gear circuit, which will take time to remedy - cue service going to hell in a hand basket.

25kV uses lightning/surge arresters which may require replacement after a strike, if they've suffered damage but that shouldn't otherwise preclude a rapid return to normal service.
--- old post above --- --- new post below ---

Here are some Glasgow details:

http://www.scot-rail.co.uk/page/electrification

http://homepages.enterprise.net/iainlogan/railway/gse1.html

I can't remember the last time I heard of a transformer explosion, as with most things electrical in nature, better manufacturing tolerances and advances in polymeric insulation, combined with better thermal controls and higher quality oils has tended increase transformer reliability enormously.

 

[snowball]

According to #231 the explosions were when the on-train equipment failed to switch from 6.25 to 25 kV, so it was trying to output four times the intended voltage. As there's no 6.25 left, that couldn't happen now - unless on a future 750/25000 tram-train!

 

[JohnElliott]

The report's available online: Failures of Multiple-unit Electric Trains on British Railways: Final Report

The transformer explosions weren't just caused by the equipment failing to switch from 6.25kV to 25kV -- in the case of the Glasgow units, part of the problem seems to have been the mercury-arc rectifiers backfiring, causing damage to the transformer windings. As the report points out, the long-term solution was to use semiconductor rectifiers instead.

There is also a mention (paragraph 285) of an AC locomotive selecting 6.25kV on a 25kV section, so at least some of them must have had changeover equipment.

 

[AM9]

... There is also a mention (paragraph 285) of an AC locomotive selecting 6.25kV on a 25kV section, so at least some of them must have had changeover equipment.

I think that the AL1-5 designs had four primary windings on the transformers, - by the time that the AL6s (class 86s) were commissioned, the problem had been resolved so they had single primary windings. Similarly the AM10 (class310) EMUs which were originally deployed on the LMR south services out of Euston I believe had single windings. The later class 312 was introduced specifically for the GEML post conversion to all 25kV, and to supplement the class 310s already in use on the WCML.

 

[XDM]

My dictionary says 'electrocute is to injure or kill someone by means of an electric shock'. It's from Oxford, they might change the definition when they get their own 25kV wires for GWR drivers to crash into.

The official UK dictionary,the concise Oxford dictionary, which I have before me says electrocute; 'kill by electricity. Cause death by electric shock.'
And that's it,take a look. And bollox,which the same poster used,does not exist.
Not trivial because the important stats about people killed by AC & DC have NOT been provided. And what is the source for the information that was given,thin air? I hope not. But seriously, provide the source & it will advance the argument,otherwise it is no more than the dross that blows around the Nulabor plain.

 

[AM9]

The official UK dictionary,the concise Oxford dictionary, which I have before me says electrocute; 'kill by electricity. Cause death by electric shock.'
And that's it,take a look. And bollox,which the same poster used,does not exist.
Not trivial because the important stats about people killed by AC & DC have NOT been provided. And what is the source for the information that was given,thin air? I hope not. But seriously, provide the source & it will advance the argument,otherwise it is no more than the dross that blows around the Nulabor plain.

Ignoring the abusive language, none of this dancing on the head of a pin here is going to change the position regarding 3rd rail. The stats regarding actual deaths caused by OLE vs 3rd rail are not relevant. The risk assessment is the correct tool to determine the way ahead which is that no new 3rd rail mainline routes will be sanctioned. 25kV OLE is the only viable and acceptable system approved for mainline use.

 

[najaB]

The official UK dictionary...

There is no such thing.

 

[GRALISTAIR]

Ignoring the abusive language, none of this dancing on the head of a pin here is going to change the position regarding 3rd rail. The stats regarding actual deaths caused by OLE vs 3rd rail are not relevant. The risk assessment is the correct tool to determine the way ahead which is that no new 3rd rail mainline routes will be sanctioned. 25kV OLE is the only viable and acceptable system approved for mainline use.

And this IMHO is the crux of the matter. A well balanced reply. Thank you.

 

[Philip Phlopp]

There's no official UK dictionary, but there is an official UK policy on third rail, and it's small scale infill only.

My previous extensive comment on the matter.

http://www.railforums.co.uk/showpost.php?p=2519836&postcount=35

And I think I need to apologise - DC is only four times as dangerous as AC. I'll go see if I can find the documents in question, and if they're in the public domain, I'll link to them.

 

[XDM]

If you can get those statistics,& their provenance& their assumptions it would enable everyone to draw sensible conclusions, anything else is no better than coronation street gossip. The Oxford dictionary is the only one used by the BBC I was told by a friend a few years ago. All queries about right usage are judged by the Duty Editor (their fat controller) byreference to the concise Oxford dictionary. And if any outfit is accepted as official it is the BBC. QED.

 

[najaB]

The Oxford dictionary is the only one used by the BBC I was told by a friend a few years ago...

Oh, the irony! Basing your definition of what is 'official' on something a friend told you. While ignoring the definition of 'official' in what you consider to be the 'official' dictionary: "Derived from, or having the sanction of, persons in office; authorized or supported by a government, organization, etc.; hence (more widely) authoritative; formally accepted or agreed."

The BBC doesn't have the authority to sanction the use of one dictionary over another, hence their use of the OED doesn't make it 'official' in any way.