renegademaster
Member
Has "very short range" battery EMUs been tried? Ones that could switch at line speed to the battery to zoom under a bridge and put the panto back up ?
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Should the ORR be friendlier to third rail?
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devon_belle
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This sounds like a recipe for disaster!
renegademaster
Member
I know it sounds mechanically fragile but don't the bimode Azumas do it on a few bridges on the Great Western mainline? I vaguely remember reading about it a while back but can't seem to find the details
AFAIK they did it at one bridge that had a very specific set of circumstances where the wire height gradient was not compatible with 125mph running.
If it's only the length of the width of a bridge you don't need batteries unless the linespeed is very low, as you could just coast under like you do a neutral section. And OLE stopping at problem bridges would bring it's own problems for tensioning and whatnot that would require more fiddling to resolve (by no means impossible, just extra faffing and therefore cost).
Steventon Bridge. https://www.railengineer.co.uk/steventon-bridge-overcoming-the-obstacle/ Is a good article on the issue and the work done to have electric trains running under it.
Buttsy
Established Member
Reading through this thread, it seems to be that if 3rd rail is to be extended, all foot crossings would need to be replaced by bridges and additional measures required at platform ends and at level crossings to avoid the possiblity of someone ignoring the signs and walking down the line onto the 3rd rail. I am assuming that the above is the reason why 3rd rail extenstions aren't economic (as well as teh outdated points made).
In a recent Modern Railways, Alan Williams worked out that, economically and enviormentally speaking, the extention to Headbolt Lane would be better in the long run to have electrified it 3rd rail due to the extra costs of replacing the batteries in the units, the additional carbon emitted in building replacement batteries and the extra cost of electricity (and potentially extra carbon emitted in producing it) for lugging around said batteries for the next 30+ years.
As others have mentioned, there are routes that the ORR should consider as being allowable for 3rd rail, subject to stringent and specific safety requirements. I would consider the follwoing to be reasonable:
North Downs
Marshlink
Uckfield (and any potential extension to Lewes)
Kirkby - Wigan Wallgate
Ormskirk - Burscough Bridge (new link allied to Preston - Ormskirk services being diverted via Burscough Bridge to Southport)
Ellesmere Port - Helsby
There are a couple I would conisder as a 50/50, due to potentail for the routes to be OHE instead:
Reading - Basingstoke - Salisbury
Salisbury - Redbridge/Eastleigh.
In a recent Modern Railways, Alan Williams worked out that, economically and enviormentally speaking, the extention to Headbolt Lane would be better in the long run to have electrified it 3rd rail due to the extra costs of replacing the batteries in the units, the additional carbon emitted in building replacement batteries and the extra cost of electricity (and potentially extra carbon emitted in producing it) for lugging around said batteries for the next 30+ years.
As others have mentioned, there are routes that the ORR should consider as being allowable for 3rd rail, subject to stringent and specific safety requirements. I would consider the follwoing to be reasonable:
North Downs
Marshlink
Uckfield (and any potential extension to Lewes)
Kirkby - Wigan Wallgate
Ormskirk - Burscough Bridge (new link allied to Preston - Ormskirk services being diverted via Burscough Bridge to Southport)
Ellesmere Port - Helsby
There are a couple I would conisder as a 50/50, due to potentail for the routes to be OHE instead:
Reading - Basingstoke - Salisbury
Salisbury - Redbridge/Eastleigh.
HSTEd
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There are several sections where there are only limited numbers of footbridge crossings et al. (I've gone on about it enough, but the Aylesbury to Amersham section is an obvious example, it only has four foot crossings I believe).
The greater issue is the practices involving staff trackside with the electrification live.
One of the reasons LU is exempt from the third rail ban is because they have adapted their working practices to mitigate against the risk of staff electrical shocks from the traction equipment.
It is likely that a total change in operational practice would be necessary to bring additional third rail to network rail lines.
(Or just transferring them wholesale to LU).
The greater issue is the practices involving staff trackside with the electrification live.
One of the reasons LU is exempt from the third rail ban is because they have adapted their working practices to mitigate against the risk of staff electrical shocks from the traction equipment.
It is likely that a total change in operational practice would be necessary to bring additional third rail to network rail lines.
(Or just transferring them wholesale to LU).
Bartsimho
Member
Could it be worth it to transfer the Chiltern services to Aylesbury to TfL under the London Overground brand then. Although it's not in London but the way the lines are it would be a nice separate section away from the rest of the NR network with the exception of Platform 3 at Aylesbury. Especially as it received service by LPBT (London Passenger Transport Board) and it's successors until 1961. If it had maintained service until the 1964 cuts it could have moved over to London Transport in a fuller capacity.
So my idea would be transferring services from Marylebone to Aylesbury via Harrow and Amersham to London Overground and extending the 3rd/4th rail all the way to Aylesbury Vale Parkway.
Not entirely unlike the South Wales Metro electrification, missing out the wires where it's inconvenient to put them up and usiung batteries for those bits, changing from battery to overhead power on the fly.
That was done by going over to diesel though, not batteries.
(Pedantic note - GWR doesn't have Azumas - that's LNER).
No, never. However, I wonder if a sensible half way house exists. Build the fourth rail out to Aylesbury Parkway, pay TfL to manage it, but have Chiltern run the services. Chiltern have to find suitable stock and drivers, TfL can do the safety training. Build a new fourth rail depot for Chiltern north of AVP and sell the current one for housing.
randyrippley
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It is to badgers and they are a protected species
renegademaster
Member
And I'm sure wind turbines kill endangered birds but they are still a net benefit over the alternative
That is a shame about the badgers. However I imagine that badger casualties will be far fewer than those resulting from the culls instigated to control bovine TB.
33,000+ killed in the 2022 cull, 100/mth from 3rd Rail on newly electrified Hastings line in 1986, so 1,200/yr. The Cull is certainly more lethal, although you'd kind of hope so. However arguments to lessen third rail safety assessment thresholds on the grounds of other more lethal risks to Badgers would be a particularly bad case given how little badger safety factors into the current decisions (sorry for the 'current' pun).
Railways and Badgers
Badgers, Electrocution, Electrified, Electrical, Death, Railways, Tonbridge, Hastings, Crossings, Fencing, Safety, Casualties
www.badgerland.co.uk
Note both sources are pro-badger.
The Badger groups have outlined some sensible measures that could mitigate the risk.
Risk to Badgers isn't what is preventing third rail installations.
devon_belle
Member
If we extrapolate to all third rail, this would be around 50,000/yr (assuming the figures for third rail mileage I found were correct). In reality it would be more nuanced than that, and as you say badgercide is not the reason for no more third rail, but that's still a lot of badgers!
There are already plenty of measures that mitigate the risk to humans - including using language to communicate the several hundred volts of electricity running through it.
Presumably if there were hundreds of badgers being killed every month on every comparable stretch of third rail, it would have made the news ?
Perhaps its one of those things wildlife learns to avoid as dangerous (like a big snake perhaps).
Presumably if there were hundreds of badgers being killed every month on every comparable stretch of third rail, it would have made the news ?
Perhaps its one of those things wildlife learns to avoid as dangerous (like a big snake perhaps).
Well you'd also have to account for a certain amount of 'learning' from the Badgers, as well as more effective mitigation methods in use today than 40 years ago.
And yet, we still have plenty of accidents. Even among humans who have been on extensive training courses about how to manage the dangers of it. But we've been through all this before. You believe the risk isn't serious enough to justify the extremely high safety threshold. The ORR disagree. Although I do wonder how the defence of 'well he/she/it should have known the rail was there' goes down with the man in the wig.
Indeed. We all know where we stand.
I have to admit, the badger situation was new to me though.
Snow1964
Established Member
It is the cost of making the third rail safe, (extra safety shielding) along with underestimation of alternative diesel costs.
What tends to happen is many of the indirect costs, maintaining diesel engines, someone getting burnt on hot exhaust, fueling spill risks etc are not subtracted from the third rail risk appraisal. It is seen as a risk project in stand alone form, not an alternative set of risks because the current diesel risks will be discontinued on that line instead.
The reality is the 171s might displace something like a class 153, and the line being electrified gets trains built to 21st Century safety and crash standards, which overall improves safety. It is this sort of indirect improvement in risk that seems to be too difficult to calculate so is often ignored
If it were the case of establishing a new third rail island, detached from existing systems then it would be quite reasonable to insist on full, modern ORR standards.
However, the likely minor extensions to a large existing network ought reasonably to have grandfather rights, substantially, in terms of safety (there are no doubt sensible improvements possible). If not then there should be proposals to eliminate existing third rail if it really is "unsafe", which I would then understand and support. LUL 4th rail is far more unsafe, with the -210V rail bisecting the existing suicide pits, yet ORR would not dare intervene.
This is in my view, the hypocrisy of the ORR stand that makes such a "safety case" unworkable. Safety decisions should not be left in the hands of the risk averse.
WAO
However, the likely minor extensions to a large existing network ought reasonably to have grandfather rights, substantially, in terms of safety (there are no doubt sensible improvements possible). If not then there should be proposals to eliminate existing third rail if it really is "unsafe", which I would then understand and support. LUL 4th rail is far more unsafe, with the -210V rail bisecting the existing suicide pits, yet ORR would not dare intervene.
This is in my view, the hypocrisy of the ORR stand that makes such a "safety case" unworkable. Safety decisions should not be left in the hands of the risk averse.
WAO
renegademaster
Member
I thought LU system was isolated from ground so nothing would happen if you touched a conductor rail and either the running rail or the ground? My electrical understanding is pretty low though
AlbertBeale
Established Member
But lines carrying a voltage need to be isolated from the ground, otherwise the voltage wouldn't last long... If you think it's safe to touch an LU conductor rail and a running rail at the same time, I'd rather not be around when you try it.
The working of a third-and-fourth rail train depends only on the potential difference between the third and fourth rails. You can change the voltage difference between these and the running rails (or the ground) and the train would not notice. But the running rails are inevitably at a different voltage from at least one of the two conductor rails (usually designed to be different from both) and if you bridge this difference it can kill you.
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I think it would make more sense to bind the 4th rail to the running rails on existing shared track similar to how the wimbledon branch operates so chiltern can just acquire third rail emus to operate the line, S stock trains are already capable of this. this allows the line to be electrified with 3rd rail.
AlastairFraser
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4th rail stock isn't much different electronically, so if ordering new DC stock, you could order stock with 4th rail shoes and 50 miles of battery capacity.
Install chargers at AVP and Marylebone - the currently unelectrified section is approx 22.75 miles, then you can bypass ORR objections completely.
The only potential issue I could think of would be the supply of current on the shared section with LU, but otherwise, it would be a great way to cascade the 165s and reduce pollution in and around Marylebone.
Blindtraveler
Established Member
I'm firmly in the camp of we need more third rail and not just for infilling the odd gaps either, I feel sure that it must be cheaper to install even if it's not necessarily cheaper to maintain but life cycle in general throughout the time it exists must surely surely surely be lower than the massive infrastructure projects we've become used to seeing with entire stations being effectively raised to the ground and started again for the sake of installing overhead wires
Not to mention tunnels and bridges requiring so many modifications
Not to mention tunnels and bridges requiring so many modifications
Falcon1200
Established Member
There can certainly be much work required for overhead electrification, in Scotland Glasgow Queen Street and Winchburgh Tunnels, for example; But I'm struggling to think of any stations which have had to be razed to the ground in order to install the wires.
I won't be trying to touch live rails on the underground.
But it depends on what you mean by isolated. Certainly there must be a suitable resistance between live and neutral to avoid excessive current from flowing but that's not what would normally be meant by isolated.
The live wire in a mains socket has a potential difference of 230 (ish) volts above neutral, which is normally at ground potential.
If you grab the live wire, you make a circuit, have a 230 V potential difference between your hands and feet and the current will flow through you to ground, which is not good.
But if you feed a transformer with the live wire and neutral and don't tie anything on the other side to ground, then in principle the voltages are now isolated from the ground as transformers don't pass DC.
This would be the normal definition of being isolated from ground.
There is a potential difference of 230 V between the two wires but not between either of the wires and ground.
So in an ideal world (which this isn't, so don't try it!) you can touch the live wire and you will be fine. The live wire will move to (near) ground potential and the neutral will now be 230 V below.
At this point the neutral is no longer safe to touch - you'll still get the full 230 V if you hold both live and neutral wires. But not, in principle, if you just touch one or the other.
In a similar manner, you can touch either terminal of a battery and not get an electric shock, but - if the voltage is high enough - you will get one if you touch the postive and negative terminals at the same time.
There is a high resistance between the two terminals (otherwise the battery would quickly discharge itself) but it's isolated from ground.
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