In terms of changing between 1.5kV DC and 25kV DC in 'neutral sections' the 2019 IE Electrification report gave this example from SNCF
Regards my previous query about DART existing total power, i'd noted that i'd found a reference that the Netherlands electrical current for its 1.5kv DC system, is 4000 amperes (Amp.), so its maximum electrical power to its trains is 6MW (half the Italian power)… but the only reference to the DART was below quote from this thread:
Railway electrification — boards.ie - Now Ye're Talkin'
that stated:
'Current DART spec is for a dense 8 car service so is modeled at 2-2.5MW per train, thats roughly the power output of a 201 class locomotive'
So, this mean DART's (or if ever future electric locomotives?) would only have just under approximately half the MW power as is available to Netherland's 1.5kV DC stock?
Anyway, as other posters have said, its not uncommon to have dual, or even triple voltage railway stock, with even quad voltage possible and for some electric locomotives, and e.g. the Netherlands ICNG having three different versions depending on the different dual, or triple voltage combinations they have for cross border services (1.5kV DC / 3kV DC / 15kV AC / 25kV AC).
I've also seen references to Belgian and Italian 3kV DC railway stock going into Netherlands, and French 1.5kV systems respectively, under reduced or half-power (reduced power either mechanically in previous times, but electronically controlled in more modern traction and not so straight-forward?).
I'm also not sure if the IE electrification report synopsis about using of 3kV DC for the DART requiring a change of system equipment (a change of system equipment also cited as required for change to 25kV AC) tallies with some of the Netherland's documents which seem to indicate mostly 'additions' only to their 1.5kV DC system to change it to 3kV DC (aka addition of transformers to substations and 'down choppers' to existing rail stock if they were converted). But regardless, there would still probably be some increased clearance considerations at existing tunnels (but just less so for 3kV DC than for 25kV AC).
It is exactly the reason. The report with that conclusion is attached to an earlier post here by @A1ACo. Here's the link again:
https://www.dartplus.ie/getattachment/1b0a4eed-b96f-4752-bdff-a747d08a772b/Annex-5-1-DART-Expansion-Rail-Electrification-Assessment.pdf
The authors repeated an analysis first done in 2011 but using new population and usage projections and updated plans for the network future. They investigated and costed three general scenarios for expanding the DART system: A. extend the 1500 V network; B. keep the existing 1500 V and build the new part at 25 kV, use dual-system rolling stock (there were two versions of this approach considered); C. switch to 25 kV, replacing the existing 1500 V DC with 25 kV AC, and use AC-only rolling stock.
Of those three general approaches, the 1500 V DC option won out on cost and risk grounds. This was the same result as 2011.
Of the other options, a mixed-voltage systems were rejected because it increased the cost of implementation, increased operational risks, made the rolling-stock more expensive and prevented existing rolling-stock from ever using the extended sections of the DART network. The all-AC option was considered a good technical approach, but it would have been highly disruptive and it nearly doubled the cost of the DART+ project due to the need to re-electrify and existing electric railway, replace DC substations with (fewer, but higher-power) AC ones, and replace all of the non-life-expired 1500 V DC rolling stock (now made obsolete) with new AC stock.
The orders for DART+ rolling-stock were based on the findings of this report, and it also informed the request-for-tenders for new Enterprise stock: 1500 V DC operation would not have been needed if DART was switching to 25 kV AC.
The choice of AC versus DC also affected the design of the network itself: DC needs more substations to be built than AC, and each substation needs to be designed and be included in the Railway Order application.
"Again, we are only expanding our 1500 DC system because we've a large investment that we would otherwise lose completely"
That can't possibly be the reason. Like the decision would've been made when the order was placed surely? Orders weren't placed in a vacuum devoid of future planning.
I wasn’t suggesting this; I was probably arguing against it. And really, the only place where they possibly could have 25 kV alongside 500 V would be on the 4-track approach to Heuston, where DART and IC trains are segregated anyway, but as I said this creates an operational problem where none needs to exist.
Connolly has too many shared stretches for mixing.
I suspect we'll have a “pale” of 1500 V in Dublin, with the rest of the island at 25 kV. An odd arrangement, but nothing unsual internationally, and it has saved hundreds of millions on DART+.
Re your point about the fast lines on a 4-track section being 25KV AC and the slow lines 1500V DC, that is anon-starter. You make life impossible at Connolly if there is a mishmash of AC and DC lines: heaven knows its bad enough already. Just as with Hazlehatch, you have a point on the Northern line where everything goes from DC to AC. The DART stock can stay DC, but interciy stock wuoul be dual voltage. Dual volatge trains are pretty standard stuff: dual voltage rail lines are a total non-runner.
DART+ fleet will have fully automated on the move transitions from OHLE to battery and back again
On the move is straightforward, done probably thousands of times a day across Europe What you need is a level piece of track where the train can coast through during the transition where it won’t get stopped
It is possible to do on the move, however it does put extra strain on the OHLE and usually they have to reinforce the OHLE where it happens. There have also been cases where the rising pantograph pulled down the cables!
In the UK they avoid doing it on the move wherever possible, most of the changeovers are done statically in stations, with only a few exceptions. Given IR’s conservative nature, I suspect they prefer to do it at a station, to reduce risk.
It's not distance, it's population: number of paying customers served per substation is the measure that matters. I listed the intermediate stops up to Drogheda, and the one after it.
Nothing in NI will be 1.5kV DC. It's completely against NIR's long-term electrification plans, and against UK rail electrification practice in general. There's no problem running commuter rail on AC: most German S-Bahn services (all but Hamburg and Berlin’s hybrid Metro/S-Bahns) are on the same AC system as the national rail.
Again, we are only expanding our 1500 DC system because we've a large investment that we would otherwise lose completely (why we made that investment rather than choosing 25kV AC is an interesting discussion, but there were good reasons). If starting from scratch, as NIR is, there isn't that much an advantage.
See my reply above. My point is the Dublin - Belfast line should be considered and either do the whole lot in one voltage or maximise the distance of 25kV AC. Going with 1.5kV DC for one third and 25kV AC for two thirds doesn’t make much sense, particularly as 1.5kV DC is more appropriate for much of the 25kV AC section.
But if going with 1.5kV DC from Malahide to Drogheda, why not do the same for Drogheda to the border which is much the same distance? My point is that they are accepting the substations requirement to Drogheda, why not accept it beyond?
We wouldn't be "forcing" NIR to do anything but it would make sense for them to coordinate with us as the networks are connected (ideally planned and operated as a single network, like the electricity grid). What is done on a separate network in Britain is irrelevant.
There are stopping services from Newry to Belfast so 1.5kV DC is most appropriate there. If going with 1.5kV DC between Dublin and Drogheda, the only place 25kv AC really makes sense is between Drogheda and Newry. Given the relatively short distances involved, one voltage makes sense. It would simplify the Enterprise new stock if the plan if the dual voltage requirement was removed.
The only possible aspect that would 'force' 1500v on NI is if they wanted to electrify their own commuter lines and wanted to go DC, they 'might' choose 1500v so they could borrow DART stock for flexibility and the intercity could use 1500v as specced.
Drogheda is the logical switchover point, nowhere else makes a lick of sense
I can't see it anywhere but Drogheda. There's no point in extending a 1500 V DC network through such a sparsely-populated part of the country. Between Drogheda and Malahide you have Bettystown/Laytown (population 15,000), Balbriggian (24,000), Skerries (10,000) and Donabate (10,000). Between Drogheda and Dundalk there's only Dunleer (population 2,000).
1500 V DC is expensive over long distance; that extra cost only pays off when you've got a lot of traffic on the line: the section north of Drogheda is unlikely to every see more than 3 trains (total) an hour.
Changing from system to system while on the move is possible, but it's always preferable to do it at lower speeds.
There's an interesting, but off-topic here, question about what happens to the "fast" lines on the quad-track section into Dublin: they could be electrified at 25 kV as they'd be limited to long-distance use, but I can't help thinking that making them 1500 V too would provide a lot more operational flexibility to IÉ: basically, if all approach lines are 1500 V, then any EMU can use any stretch of track within the GDA - and you can't end up stranding a DART train due to a points error.
Even if we wanted to, we could not "force" NI to install 1500V DC. They have decided in peinciple to go 25kv AC, when the oppostunity arises. The real question is will the DC-AC changeover be at Drogheda or Dundalk (i.e the border). AFAIK, you can change from one system to the other while on the move, as elsewhere in Europe.
The new DART trains are specified and built to run on 1.5kV DC, they aren’t dual voltage, unlike the upcoming Enterprise fleet.
So if Malahide to Drogheda was 25kV AC, then our DART’s couldn’t run on the OHLE, they would need to use the batteries for the lifetime of the trains, 40+ years. I suppose you think you could retrofit dual voltage on the DART fleet, but that would be extremely costly to do and would add unwanted weight and complexity to the DART fleet.
Every 10 minutes you’d have DART’s switching pantographs at Malahide, a complete nightmare scenario for reliability.
No, this really doesn’t make any logical or economic sense. 1.5kV DC to Drogheda makes sense, it allows us to keep the DART fleet simple and reliable, just regular single voltage operation like we have already been doing for the past 40 years. While Drogheda is the perfect location for the Enterprise to switch between 25kV AC and 1.5kV DC as it stops there anyway. Keep in mind the DART fleet is much larger then the intercity fleet and also much more important. Reliability is key for commuter services. I literally can’t think of a single benefit of doing 25kV from Malahide:
And your comment about the government long fingering Drogheda electrification makes no sense, why would they long finger that, only to turn away and then approve 25kV to Malahide instead, that doesn’t make logical sense.
Why would we try to force NIR to install any 1500 V DC systems? There are no 1500 V mainlines at all in the UK (Tyne and Wear Metro is the only railway of any kind to use it), and NIR has always relied heavily on engineering guidance from other UK operators.
The decision to use 1.5kV DC in the Republic is because we have a significant investment in 1500 V rail that we would lose completely if we changed. From. NIR's point of view, deliberately starting a two system network is stupid.
Also, using 1500V means building a substation every 6-8 km. That's acceptable in a populated area where you've got towns (and stations) at the same kind of distances from each other, but it's not true north of Drogheda. For 25 kV the spacing is over 30 km, which is much more suited to a railway through a more rural area.
I was one of them for a time but was one of the fortunate ones to be able to jump onto a bus.
All I can see over the last decade as a daily user is a continual disimprovement on almost all fronts.
new carriages and signalling will increase capacity. The carriages have started arriving and the signalling has been installed on the existing Dart line.
Punctuality should (in theory) improve with the new signalling but it'll still be Irish Rail running the system and I don't have much confidence in them. I got the Dart yesterday and the morning train was 10 minutes late and the evening train 15 minutes late. This is after they rolled back their timetable changes to "improve punctuality". Meanwhile on the northside some people were trapped on stationary trains for up to an hour due to a signalling failure.
Other than waffle and costly consultant's reports, is there anything in train right now with Irish rail?
I don't mean timetables, new carriages or signalling. But something that will actually increase capacity and improve punctuality in Dublin?
The RO is one thing but it remains to be seen if that actually happens. The BEMUs make it very easy for the government to put that part of DART+ Coastal North on the long finger (other aspects of it have to happen to facilitate increase in services).
I didn't say anything about not electrifying the line so not sure why you are talking about the cost of the batteries over the next 40 years. My point is that electrification doesn't necessarily have to be to 1.5kV DC. If going with that, probably best to continue it all the way to Belfast and not needing Enterprise trains compatible with 25kV AC.
We already are the laughing stock of Europe.
The Railway Order submitted for DART+ Coastal North is for Malahide to Drogheda to use 1.5kV DC. The RO hasn't been approved yet, but assuming ABP do, then it is pretty much set in stone.
It is just 37km, it really isn't a particularly long distance. The batteries taking us to 2030 isn't the point, it is the cost of the batteries over the next 40 years or more. Replacing the batteries 4 or 5 times over a 40 to 50 year lifetime of the train versus electrification.
You also have the consider the 3 BEMU's versus 5 EMU's from Drogheda, that isn't a small matter. The options report looked at options from 5 or 6 BEMU's from Drogheda, but apparently that involved a big increase in cost as it would require building extra sidings/platforms to hold trains for recharging. So you have to balance that big cost (+ batteries over 40 years) against the electrification.
Also DC tends to be better for DART type services, it is less complicated and allows for lighter trains.
BTW The options reported goes into the cost of different options, but all the info is redacted as it was a Freedom of Information request. However the impression I get is that electrification is a serious money saver in the long term.
Yeah, I doubt there would be any issues with electrification. But that was sort of my point if something relatively easy like electrification doesn't get approved, then no hope for quad tracking as that will be more controversial. The overall point being I assume Drogheda will be electrified and that the Enterprise replacements will switch over while stopped at Drogheda.
BTW the electrification part of the DART+ West got approved by ABP without any notable issues. Just the depot that was the major issue and junction closures. I don't see electrification being a big deal on the Northern line, it should be relatively straight forward.
You fear that "if they can't get electrification through planning", is I hope unwarranted. It speaks volumes about the planning czars that there should be any possibility of electrification being blocked. We would be the laughing stock of Europe.
I was thinking that services north of Malahide would be operated using 25kV AC stock. It is probably more appropriate for that type of outer commuter service. The logic behind using 1.5kV DC is allowing for DARTification but doing that with BEMUs probably negate much of that logic now.
Regarding electrifying being cheaper in the long run, would that also apply to 1.5kV DC over such a distance? The batteries would take us well into the 2030s, really should be electrifying all Malahide - Belfast in one go at that stage.
I believe operating BEMU's in the long run is more expensive then electrifying. The engineering options report mentions having to replace the batteries every 9 years, and remember you have to do that on both the trains and the BESS in Drogheda. Cost probably adds up over time.
Plus you are limited in the number of BEMU's you can operate out of Drogheda. I'm not 100% which option they went with, but I think it is just 3 trains per hour out of Drogheda. With electrification they are planning 5 trains per hour.
If BEMUs are doing the job between Malahide and Drogheda, why would you go to the cost of electrifying at 1.5kV DC? Surely it'd be better just going with 25kV AC and doing Malahide - Belfast in one go.
From Malahide they would likely be operating at slower speed anyway. I'm sort of assuming that if you can't get electrification through planning, you are even less likely to get quad tracking of the northern line, so they will be stuck behind DART's anyway.
Or if electrification isn't extended to Drogheda, they don't even bother with 1.5kW DC at Malahide given the relatively short distance. Just operate on Diesel + Battery to Connolly. Might be a nice way to embarrass the government into getting electrification done.
Yes, but if delivered before OHLE reaches Drogheda, the transition would be Malahide.
Not sure there's as many entitled lawyers to throw JRs in against DART+ North, but nothing can be trusted here.
Doesn't the Enterprise normally stop at Drogheda anyway? Do it when stopped at the station.
Going to be interesting to see what speed (if any) they can change from OHLE <> diesel at. Putting pantographs up at speed isn't the safest thing to do.
You are correct, at least according to the tender description, it says:
Initial traction power will be Internal Combustion Engine (ICE) Battery Electric (using the existing 1.5 kV DC OHLE) with the train designed to transition to a net zero carbon operation during its life by the removal of the diesel power generation for replacement with dual OHLE power supply equipment.
So initially it will be Diesel generator + battery + 1.5 kV DC OHLE, with in future the Diesel generator being removed so Battery + 25kV AC + 1.5kV DC
The market consultation document specifically mentions that NI Railways are planning to install 25kV AC from Belfast to the border.
I suppose that could allow IR the option of either continuing 1.5kV DC from Drogheda to the border or also switch to 25kV AC from Drogheda to the border. But either way it would end up Dual voltage.
On the battery, I'd assume it will have relatively smaller batteries then the DART BEMU's. More a hybrid type battery setup, focused on enough size to take advantage of regenerative braking and allow the Diesel generators to run at a more efficient level. Maybe allow them to idle on battery while in stations and perhaps even run on battery on the approaches to stations at lower speeds. Would help cut down emissions on and near stations.
