Comparison of safety between overhead line vs third rail electrification systems

[XDM]

If you look at HSTed's figures again - (they are analysed at post 35) they show that third rail electrification is not just "marginally" more dangerous but 16 times more dangerous (happy to be corrected).

This has been stated repeatedly before, but the Network Rail figures claiming dc is more dangerous than ac are entirely a desk top assessment of risk. They are NOT based on the actual death stats from ac versus dc electrocution. Despite asking a regular ac poster about a year ago for the real stats he was quoting he did not produce them. NR is not an impressive organisation, it has failed too many times,despite some very talented & energetic people working for it. For a long time NR were very pro ac & anti dc, and a desk top risk assessment can easily produce the conclusions that managers want, rather than real world figures. But now I sense that a few at NR are feeling slightly warmer towards dc electrification, if only because it is easier for a failed organisation to manage than complicated ac overhead.

 

[edwin_m]

I don't disagree about AC. But at the same time when did we last hear of a DC upgrade going wrong in any way at all? If any have run seriously late they haven't had much publicity...

In terms of new DC electrifications, the only one this century of any size would be the East London Line, not on Network Rail infrastructure and with the benefit of a long blockade. There have been significant power supply upgrades to the existing network when people realised that Electrostars and Desiros would break the system, and even since then they are current limited on DC. I don't know how those did relative to budget.

 

[HSTEd]

If you look at HSTed's figures again - (they are analysed at post 35) they show that third rail electrification is not just "marginally" more dangerous but 16 times more dangerous (happy to be corrected).

The argument is that both of those statements are true.
It can be 16 times more dangerous but still not be particularily dangerous.

Borderlands will be one of the last lines to be electrified unless the Welsh Government decided to fund it which is highly unlikely. It has been talked about for decades without any real progression.

It is also a handy line in DC territory that wouldn't be catastrophic for the local economy if the project went badly.

Wigan Wallgate to Skelmersdale and or Kirkby would be better as AC. While linking Skelmersdale with Liverpool is the primary object of the new line plan it would be odd to rule out services to Manchester. Merseyrails new rolling stock has been designed to be converted to dual mode

Do Merseyrail trains catch fire if they go into Greater Manchester or something?
Why can't the conversion point simply be at Wigan Wallgate and have all trains run by Merseyrail using an add-on to their order from Stadler (who made their name making small numbers of units regardless.
Or even run the services between Skelmersdale and Manchester with dual voltage units..... like those 319s already deployed with Northern?

and half of services from Liverpool would terminate at Kirkby in the event of either simple electrification to Wigan or building the Skelmersdale link. The main limitation to AC conversion on Merseyside is the loop and link tunnels height. I wouldn't guarantee that the existing Merseyrail network will stay 3rd rail let alone be expanded. Liverpool South Parkway to Hunts Cross would very likely be converted to AC if the CLC is electrified. Merseyrail would either have to use dual mode trains or stop serving Hunts Cross.

Or more likely any through-CLC trains will simply use dual voltage units and things will stay as they are?
Given that the CLC Is not the fastest route between Liverpool and Manchester any electrification scheme would likely see the route cut in half at Warrington Central anyway.
Warrington Central to Hunts Cross would then be electrified at 750Vdc and turned over to Merseyrail to operate as an extension of Hunts Cross services.

Even before the AC electrification programme hit the rocks it was extremely unlikely that anyone was ever going to actually pay money to rip out good DC electrification equipment to replace it with AC [look how the Electric Spine went down like a lead baloon]- and now it is most certainly not going to happen.

We are swimming in dual voltage units.

 

[Elecman]

In theory yes but you should never assume. there was an incident a while ago were a driver was electrocuted after coming in contact with some downed wires (he survived).

In that case the downed wire was not fully down on the ground or touching anything that was earthed hence why it remained live.

 

[Chester1]

It is also a handy line in DC territory that wouldn't be catastrophic for the local economy if the project went badly.

Even using a very optimistic cost estimate the business case doesn't add up for any kind of electrification project. The line south of Deeside Industrial Estate is 40mph and north 60mph. If the southern section was upgraded to 75mph then several minutes could be cut which would provide a much more reliable service compared with the 0 minute turn around time at each end.

Do Merseyrail trains catch fire if they go into Greater Manchester or something?
Why can't the conversion point simply be at Wigan Wallgate and have all trains run by Merseyrail using an add-on to their order from Stadler (who made their name making small numbers of units regardless.
Or even run the services between Skelmersdale and Manchester with dual voltage units..... like those 319s already deployed with Northern?

Or more likely any through-CLC trains will simply use dual voltage units and things will stay as they are?
Given that the CLC Is not the fastest route between Liverpool and Manchester any electrification scheme would likely see the route cut in half at Warrington Central anyway.
Warrington Central to Hunt's Cross would then be electrified at 750Vdc and turned over to Merseyrail to operate as an extension of Hunt's Cross services.

Merseyrail provides a reliable service and a significant part of this is opperating in a relatively self contained network. DC to Warrington would work but why DC electrify and just half the line? In the long term express services could use AC electrification and the stops between Warrington Central and Manchester can support 2tph.

Even before the AC electrification programme hit the rocks it was extremely unlikely that anyone was ever going to actually pay money to rip out good DC electrification equipment to replace it with AC [look how the Electric Spine went down like a lead baloon]- and now it is most certainly not going to happen.

We are swimming in dual voltage units.

We are talking about a mile or two of electrification! Is there a sub station on that section? Could the third rails be used as spares?

Uckfield being electrified using DC makes sense because its surrounded by DC. Extending Merseyrail is different because apart from Borderlands Line, expansion of the DC network would be on to lines that are adjacent to AC lines which fit the Northern Rail franchise better than Merseyrail.

 

[daikilo]

Happens but we've been running overheads since the year dot.Other circumstances bring the wires down.(also)

Think they could get them up faster than third rail but I'm no expert on this and I guess it depends on circumstances also.

I've worked with overheads and I think I prefer these to third rail.

We have not been running OHLE at 25kV since year dot but rather around 1960.

As regards re-inititation, a hit on an OHLE can take out the wiring whereas a foot on a live rail is likely to at worst cause a death and a fuse failure.

 

[route101]

Maybe a bit off topic but was at Carlisle and south of the station a short strecth of line is elctrified onto the tyne valley line , is that ever used or live or regularly maintained so it can be used ?

 

[Bald Rick]

I don't disagree about AC. But at the same time when did we last hear of a DC upgrade going wrong in any way at all? If any have run seriously late they haven't had much publicity...

There have been a few, but they are got round with restrictions on power draw.

Nevertheless, the reason why DC electrification upgrades seem to go well is simply because the majority of work is off the working railway, and can be done in regular working hours by people who spend all their time installing / repairing heavy power electrical equipment. This is a relatively transferable skill in wider industry, and there is a wide supply base.

With AC electrification, most of the cash is spent on the working railway, putting up heavy electrical components above the track. It is therefore much more at the mercy of the operational railway in terms of getting it done, much more visible if things don't go to plan*, and most importantly has a much more specialised and therefore constrained supply base.

* I do want a DC project to go ahead, simply to see if anyone starts a progress thread:

Day 1 "all the pots went out last night"
Day 2 "con rail installed last night"

err, that's it.

 

[snowball]

Nevertheless, the reason why DC electrification upgrades seem to go well is simply because the majority of work is off the working railway, and can be done in regular working hours by people who spend all their time installing / repairing heavy power electrical equipment. This is a relatively transferable skill in wider industry, and there is a wide supply base.

With AC electrification, most of the cash is spent on the working railway, putting up heavy electrical components above the track. It is therefore much more at the mercy of the operational railway in terms of getting it done, much more visible if things don't go to plan*, and most importantly has a much more specialised and therefore constrained supply base.

That post may not have been intended as an argument in favour of DC electrification against AC, but it reads like one!

 

[najaB]

That post may not have been intended as an argument in favour of DC electrification against AC, but it reads like one!

It's not really. Ease of installation is only half the story.

 

[ijmad]

Personally, I think battery trains are the future, with much shorter, safer overhead sections to recharge the batteries in areas that are not accessible to the public (e.g. depots) or can be carefully guarded (e.g. above station platforms but not between stations). Will be much safer.

 

[HSTEd]

Even using a very optimistic cost estimate the business case doesn't add up for any kind of electrification project. The line south of Deeside Industrial Estate is 40mph and north 60mph. If the southern section was upgraded to 75mph then several minutes could be cut which would provide a much more reliable service compared with the 0 minute turn around time at each end.

The business case is not based on whether or not the electrification of that specific line is worth it.
It merely serves as a testbed that is nicely out of the way to perform an electrification project to see if third rail costings are reasonable.

And to determine whether the long blockade model will yield significant savings over a night-by-night scheme.

Merseyrail provides a reliable service and a significant part of this is opperating in a relatively self contained network. DC to Warrington would work but why DC electrify and just half the line? In the long term express services could use AC electrification and the stops between Warrington Central and Manchester can support 2tph.

Because it now appears that DC electrification specced to the service required would by simpler and potentailly [if the Kent route study estimates for Marshlink are accurate] cheaper than a 25kV solution.

The rest of the line between Warrington Central to Manchester can use AC and use AC units running as part of the Manchester suburban network.
In the long run all express trains from beyond Manchester and Liverpool will likely be concentrated on the fastest route.

Uckfield being electrified using DC makes sense because its surrounded by DC. Extending Merseyrail is different because apart from Borderlands Line, expansion of the DC network would be on to lines that are adjacent to AC lines which fit the Northern Rail franchise better than Merseyrail.

Being adjacent is largely irrelevant - the vast majority of the service groups that would be served by DC extensions to Merseyrail will not suffer significantly from being operated as self contained operations.
Warrington Central being the break point between high intensity (4tph) Merseyrail operations and 2tph Manchester operations does not inconvenience a very large number of passengers once the express services are concentrated on the route over Chat Moss.

Extending to Helsby has no interaction with lines that are ever likely to be electrified and in any case has seperate platforms for the Ellesmere Port line.

I could go on.

 

[ijmad]

Should be noted that overhead catenaries and UK-style third rail aren't the only games in town. Other much safer systems include the Ground-level power supply (wonder if this could be adapted for heavy rail?) and bottom running shoe systems like the Docklands Light Railway which seem to be safer.

 

[edwin_m]

Should be noted that overhead catenaries and UK-style third rail aren't the only games in town. Other much safer systems include the Ground-level power supply (wonder if this could be adapted for heavy rail?) and bottom running shoe systems like the Docklands Light Railway which seem to be safer.

Introducing something different from our existing third rail system remove the main reason to consider third rail rather than OLE for extensions in existing third rail areas. Once you go for something incompatible you might as well go for 25kV.

 

[keith1879]

The argument is that both of those statements are true.
It can be 16 times more dangerous but still not be particularily dangerous.

I'm a little uncertain of your units - but your original post appears to suggest that in a year we expect 8 deaths associated with third rail compared with 1 on the overhead (where there is double the length of route electrified).

I agree that this does not make the third rail "particularly dangerous" but it is clearly a lot more than "marginally more dangerous" than the overhead electrification.

OK -it's semantics but where we only have the written word semantics are important.

 

[LLivery]

Should be noted that overhead catenaries and UK-style third rail aren't the only games in town. Other much safer systems include the Ground-level power supply (wonder if this could be adapted for heavy rail?) and bottom running shoe systems like the Docklands Light Railway which seem to be safer.

Indeed many people are surprised to see top contact third rail in this country when coming from abroad.

Personally I take some of what the Mythbusters do with a pinch of salt.

Like peeing on the 3rd rail to start with!

Anyway I will let people make their own conclusions If after watching this video you think it is ok your more than welcome to try it personally I won't be because I know what the outcome would be.

https://www.discovery.com/tv-shows/mythbusters/videos/peeing-on-third-rail-minimyth

Wasn't there a bloke who died after peeing on the third rail at SWT's Vauxhall some years back?


As for OHLE people get electrocuted nearly always for being idiots. Every year or so on tv there is someone or a family member of someone who got electrocuted because they were dumb enough to climb on top of a train, even though its bloody obvious the wires are lethal. As for third rail its normally an idiot who thinks walking along the tracks is a good idea for "fun". I never forget the one who said "I never knew the live rail could be on the outside of the tracks" like that was at all relevant. Third Rail you're just more likely to live, but its just not as good for trains.

Its strange but for the country who created railways, people are far too ignorant of how it works. In America "third rail" has become a phrase for accidental danger, in the UK no one knows what an earth it is. Maybe its time for the railway to spell out things more clearly; I don't know how its changed but in primary school we had a Network Rail thing for like 15 mins. It was basically "this is a third rail area, 750V", "keep off the track", "trains take x meters to stop". That was it. It should be more than that, arguably a whole day on how things work, tell people what points, signals, OHLE are. The science behind signalling, infrastructure and rolling stock. You again an education for something, you tend to gain some respect for it.

 

[HSTEd]

I'm a little uncertain of your units - but your original post appears to suggest that in a year we expect 8 deaths associated with third rail compared with 1 on the overhead (where there is double the length of route electrified).

It is a Fatality Weighted Injury - so injuries are assigned a fractional value based on how serious they are, with 1 being a fatality.

I agree that this does not make the third rail "particularly dangerous" but it is clearly a lot more than "marginally more dangerous" than the overhead electrification.

Well if the entire risk is small, then the total risk of a third rail railway could easily only be marginally greater than a 25kV one.

 

[Bromley boy]

If you look at HSTed's figures again - (they are analysed at post 35) they show that third rail electrification is not just "marginally" more dangerous but 16 times more dangerous (happy to be corrected).

In terms of the bald figures, perhaps "marginally" was the wrong word to use. However my thinking was that 16 times a vanishingly small risk is still a very small risk indeed (albeit the increase is quite large in statistical terms).

However I note from post 53 that the overwhelming majority of 3rd rail incidents involve trespassers. If we exclude these from the figures, the additional risk posed by 3rd rail to those legitimately on the railway can be correctly described as marginal.

 

[Bromley boy]

In theory yes but you should never assume. there was an incident a while ago were a driver was electrocuted after coming in contact with some downed wires (he survived).

Certainly the AC PTS course (mine covered both AC and DC) requires that downed AC wire is treated as live at all times. As noted previously, if not earthed, an isolated section of wire may still be capable of delivering a lethal shock.

This is made worse by the fact there is no AC equivalent of a short circuit bar to act as a failsafe.

 

[goblinuser]

In terms of the bald figures, perhaps "marginally" was the wrong word to use. However my thinking was that 16 times a vanishingly small risk is still a very small risk indeed (albeit the increase is quite large in statistical terms).

However I note from post 53 that the overwhelming majority of 3rd rail incidents involve trespassers. If we exclude these from the figures, the additional risk posed by 3rd rail to those legitimately on the railway can be correctly described as marginal.

I find it odd that you find it necessary to omit trespassers. Electricity doesn't discriminate and if it kills and injures more people, then it is more dangerous.

 

[edwin_m]

I don't consider the equivalent of eight deaths per year to be negligible. However that is for the whole existing network, whereas the sorts of decisions that might have to be made relate to extensions to the third rail network where the extra hazard would be a lot less.

Despite what some may conclude from my earlier posts, I am yet to be convinced that third rail should be ruled out for infill-type schemes on existing third rail routes. Despite the new information in the top of this thread the evidence and risk assessment to justify ORR's view on this still doesn't appear to be publically available.

 

[Grumpy]

I find it odd that you find it necessary to omit trespassers. Electricity doesn't discriminate and if it kills and injures more people, then it is more dangerous.

Given the amount of money being spent on palisade fencing and footbridges ( at least on 25kv projects-so presumably would also be spent on 3rd rail), should there be any significant number of trespassers?

 

[Bromley boy]

I find it odd that you find it necessary to omit trespassers. Electricity doesn't discriminate and if it kills and injures more people, then it is more dangerous.

Quite simply because the railway is inherently dangerous. Unless we are going to abandon it altogether it will never be 100% safe and a compromise has to be made somewhere.

When making that compromise surely the safety we should be considering is that of passengers and those working on the railway, rather than those who deliberately choose to put themselves in harm's way.

The figures show that 3rd rail is only marginally more dangerous for the former groups. Therefore there seems to be very little justification for not undertaking small extensions to the existing 3rd rail network on the grounds of safety alone.

 

[swt_passenger]

Personally, I think battery trains are the future, with much shorter, safer overhead sections to recharge the batteries in areas that are not accessible to the public (e.g. depots) or can be carefully guarded (e.g. above station platforms but not between stations). Will be much safer.

It isn't really the future except in relatively minor specific cases. Been done to death in earlier threads though...

 

[HSTEd]

I WO der if it would be possible to adjust the results to take account of the more rural nature of the 25kV system.
Lot less people to tresspass on top of Shap.

 

[edwin_m]

I WO der if it would be possible to adjust the results to take account of the more rural nature of the 25kV system.
Lot less people to tresspass on top of Shap.

On the other hand third rail routes are required to have a higher standard of fencing to reduce the trespass risk. The general policy of pallisades with nearly everything may have evened this up across the network in recent years, but it wasn't so historically.

 

[snowball]

I WO der if it would be possible to adjust the results to take account of the more rural nature of the 25kV system.
Lot less people to tresspass on top of Shap.

On the other hand lots of major cities have 25kV, whereas only London and Liverpool have third rail.

 

[ijmad]

On the other hand lots of major cities have 25kV, whereas only London and Liverpool have third rail.

Don't forget the Clockwork Orange! (Glasgow)

 

[edwin_m]

Don't forget the Clockwork Orange! (Glasgow)

However I'd guess that trespassers breaking through lineside fencing aren't a major problem on that route...

 

[ijmad]

However I'd guess that trespassers breaking through lineside fencing aren't a major problem on that route...

True, although people falling on to the tracks from the platforms and touching the 3rd rail is a risk as it is on London Underground and National Rail.