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https://assets.caselaw.nationalarchives.gov.uk/ewhc/admin/2023/3338/ewhc_admin_2023_3338.pdf 3.17. We have determined that the Applicant has not demonstrated equivalence, or better, in risk control and therefore has not provided cogent justification and reasoning why it should not progress...
There must be a study somewhere of energy losses vs an equivalent 25kV installation ( I'm sure there's some at the RSSB, but I'm apparently particularily bad at searching the research archive these days ) - does anyone have one or the results of one handy?
Network Rail estimated in 2012 that up to 27% of power input was lost in the DC transmission system and track power. Hundreds of millions of pounds every year going to waste. It's really not a sensible system for long distance use
Given the number of disruptions caused by damaged overhead power supply systems and the complexity of any track alterations once it's up I wonder what would be gained by making a change other than some increases in speed and the perceived safety aspect.
Cost of the change is why it's not being seriously proposed. Electric trains should have been running to Swansea and Bristol long before now. If that can't be afforded wiring up the huge Southern track network plus the trains and all else is a total non-starter.
Once electrification is suitably complete elsewhere it would make sense to swap over the outer areas of DC land to 25KV. Better for freight (eg Southampton), more power (eg Portsmouth Direct), fewer icing problems.
But swapping over the metro areas would be heroic - imagine doing Clapham whilst trying to keep services going,and all the bridges and tunnels across four or more tracks, finding room for piles avoiding all the 3rd rail gear, finding room for new power supplies….
Just doing the deveg in inner suburbia would cause political Armageddon
This goes back to the bigger 'investment in electric' discussion though. Yes, 25kv OHLE is better than third rail on many levels, yes we should be working on expanding electrification. In an ideal world we'd have the expansion of electrification and replacement of DC with overhead AC (all new build DC units have the capacity for AC conversion), but I'd rather the former happen than the latter, one pot of money after all.
The problem, moreso than the use of 3rd rail technology, is the use of top contact. There are more than a handful of turnkey metro solutions that come with third rail as standard, but none of them have the same risk profile. Yes, there is typically better ingress protection for metros as well - something else to consider.
If third rail is so bad why does no one talk about replacing the fourth rail on the London underground? whilst not as extreme as the underground, the loading guage and other gantries prevent OHLE from being installed on the former southern region.
If third rail is so bad why does no one talk about replacing the fourth rail on the London underground? whilst not as extreme as the underground, the loading guage and other gantries prevent OHLE from being installed on the former southern region.
Because most of LUL's network is in tunnels, there are no level crossings (foot or vehicle) and limited wildlife accessinging and shorting out on it. Whereas that isn't the case for the miles of 3rd rail outside London.
It's a commendable long-term aim, but I can't see it happening to any significant extent in my lifetime. The LB&SCR had the right idea all those years ago, mind.
Because most of LUL's network is in tunnels, there are no level crossings (foot or vehicle) and limited wildlife accessinging and shorting out on it. Whereas that isn't the case for the miles of 3rd rail outside London.
in a ideal world where all third rail national rail lines were suddenly abolished and became OHLE, what would happen to situations like the northern city line then? third rail becoming a proprietary system? and all the tunnels over the south east that are too small in loading gauge to cope with the ohle, just because 99% of the coast is in open air that doesn't mean ohle can magically fit in all tunnels and under every bridge.
Imo I think redesigning the third rail system to be more energy efficient and safer would be better long term for the third rail network.
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in a ideal world where all third rail national rail lines were suddenly abolished and became OHLE, what would happen to situations like the northern city line then? third rail becoming a proprietary system? and all the tunnels over the south east that are too small in loading gauge to cope with the ohle, just because 99% of the coast is in open air that doesn't mean ohle can magically fit in all tunnels and under every bridge.
Imo I think redesigning the third rail system to be more energy efficient and safer would be better long term for the third rail network.
There were plans to continue it to Brighton, but grouping of the companies south of
London into the Southern Railway which included the LSWR where electrification had been started using a 3rd rail system chosen following on a tour of American urban railway systems. Hence the large network of electrified track based on a decision to copy US urban practice with US levels of safety 'provision'.
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That would only reduce the icing and possibility of inadvertent human contact. All the gross inefficiency of power delivery and overcurrent protection would still be there even after a massive conversion cost and decades of severe disruption. A waste of funds compared with converting to a proper electrification scheme.
There were very small areas where DC 750v OHLE was installed - primarily in freight yards and branches where shunters needed to be on the track to split up or couple freight trains. Certainly Angerstein Wharf had a section and I think Plumstead goods yard reception roads as well to my local knowledge. These were used by the E5XXX (Class 71) electric locos. The life of this OHLE was short-lived as the 'Electro-diesels' E6XXX (Class 73) were introduced not long after.
I'd wager even if there was political will to do it, the nightmare of planning and executing would bite us in the butt again. HS2 was unable to get past Birmingham, and I'd argue a project like this trumps HS2 scale-wise purely due to the extent of the 3rd rail network, and the closures necessary to complete this work.
3rd rail sucks, but it's here and it works. I'd like to see someone try convincing the hundreds of thousands of commuters on the network that the case is there to make the conversion worth it.
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There were plans to continue it to Brighton, but grouping of the companies south of
London into the Southern Railway which included the LSWR where electrification had been started using a 3rd rail system chosen following on a tour of American urban railway systems. Hence the large network of electrified track based on a decision to copy US urban practice with US levels of safety 'provision'.
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That would only reduce the icing and possibility of inadvertent human contact. All the gross inefficiency of power delivery and overcurrent protection would still be there even after a massive conversion cost and decades of severe disruption. A waste of funds compared with converting to a proper electrification scheme.
I agree with you in that most of the network should be wired sooner, so wonder why you suggested "Maybe at some stage it will be worthwhile to convert to side contact It will be akin to re-electrification though.", as that would be a long time after at least some existing DC routes are made ac given that they would then benefit from the full range of bernefits rather than just a couple of minor improvements.
At £4m per single track kilometre, you are never going to be able to get the capital for conversion to 25kV electrification.
Even Network Rail, that long made delusional claims that renewable of third rail equipment would cost more than conversion to 25kV, have stopped pretending that 25kV is cheaper than third rail for new installations.
There must be a study somewhere of energy losses vs an equivalent 25kV installation ( I'm sure there's some at the RSSB, but I'm apparently particularily bad at searching the research archive these days ) - does anyone have one or the results of one handy?
Energy losses are not really a major driver on installation cost, and in any case require a lot of assumptions that are difficult to substantiate in simple models.
And in any case, progress with DC superconducting feeders on the continent and elsewhere (Japan etc) will likely enable heavily reduced third rail losses in the relatively near future.
Essentially everyone has given up on significant conversion of DC electrification to 25kV in any case.
You could have one or the other, I don't think you can have both... a lot of the problems are from using 650v. 25kV 3rd rail obviously isn't a sane idea
Some amount of batteries would make conversion easier, although it'd also help mitigate some of the 3rd rail performance problems ( but there's threads about that already ). You'd need less substations for HV AC, but you'd also have to go and replace pretty much all the signalling I think.
You could have one or the other, I don't think you can have both... a lot of the problems are from using 650v. 25kV 3rd rail obviously isn't a sane idea
Some amount of batteries would make conversion easier, although it'd also help mitigate some of the 3rd rail performance problems ( but there's threads about that already ). You'd need less substations for HV AC, but you'd also have to go and replace pretty much all the signalling I think.
And your HV AC substations cost orders of magnitude more, so there isn't that big a saving in substation terms!
The losses from third rail are likely to be cut dramatically if French and Japanese experimetns with superconducting feeders at 1500V pan out.
Indeed, even a 0V superconducting return conductor would cost losses substantially, as well as eliminating the vast majority of the current leakage issues.
And your HV AC substations cost orders of magnitude more, so there isn't that big a saving in substation terms!
The losses from third rail are likely to be cut dramatically if French and Japanese experimetns with superconducting feeders at 1500V pan out.
Indeed, even a 0V superconducting return conductor would cost losses substantially, as well as eliminating the vast majority of the current leakage issues.
So far, ambient superconductors have many mentions of being possible but without documented proof, real progress is about as fast as nuclear fusion* that was promised give us all "free electricity for life"!
* The UKAEA Zeta project in 1957 was trumpeting "free electricity for life". To date no such thing has even been demonstrated outside a lab.
Superconductors ( and yes, room temperature superconductors always seem the same 20 years away as fusion reactors ) would of course also help HV AC, if rather proportionately less. I'm not sure how that really helps energy loss in the conductor rails though unless you want *them* to be superconducting.
Also superconducting battery cars/trucks would possibly murder any case for long distance rail completely as well as making electrical aircraft practical, without the costs of fixed infrastructure.
So far, ambient superconductors have many mentions of being possible but without documented proof, real progress is about as fast as nuclear fusion* that was promised give us all "free electricity for life"!
* The UKAEA Zeta project in 1957 was trumpeting "free electricity for life". To date no such thing has even been demonstrated outside a lab.
They aren't ambient, they use liquid nitrogen cooling.
My earlier and unclear reference to "uninsulated" was in the electrical sense. I thought it was confusing so removed it, if that is the cause of your confusion.
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Superconductors ( and yes, room temperature superconductors always seem the same 20 years away as fusion reactors ) would of course also help HV AC, if rather proportionately less. I'm not sure how that really helps energy loss in the conductor rails though unless you want *them* to be superconducting.
The superconducting technology allows the effective distance from the substation to be cut.
If you have a superconducting cable in parallel with the track it can be coupled to the rails or return conductors every few hundred metres without the necessity of a substation or other equipment. That would slash the total losses from the system.
The couplers could potentially be spaced more closely than the train's length
It would also make it possible to operate the entire third rail system in parallel using superconducting backhaul which would also eliminate the section arcing issues.
Also superconducting battery cars/trucks would possibly murder any case for long distance rail completely as well as making electrical aircraft practical, without the costs of fixed infrastructure.
How do superconductors help cars and lorries?
Actual (operational) superconducting cables are being installed at Paris Montparnasse as we speak, and several actual real world trials have been run already
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