Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie

DART+ (DART Expansion)

1368369371373374393

Comments

  • Moderators, Motoring & Transport Moderators, Technology & Internet Moderators Posts: 23,517 bk
    Mod ✭✭✭✭


    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.



  • Registered Users, Registered Users 2 Posts: 4,348 goingnowhere
    ✭✭✭


    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



  • Registered Users, Registered Users 2 Posts: 2,186 Economics101
    ✭✭✭


    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.



  • Registered Users, Registered Users 2 Posts: 2,361 KrisW1001
    ✭✭✭


    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+.



  • Registered Users, Registered Users 2 Posts: 2,810 AngryLips
    ✭✭✭


    "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.



  • Advertisement
  • Registered Users, Registered Users 2 Posts: 2,361 KrisW1001
    ✭✭✭


    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.



  • Registered Users, Registered Users 2 Posts: 91 A1ACo
    ✭✭


    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).



  • Registered Users, Registered Users 2 Posts: 19 LastCall


    Does anyone have a higher quantity version of this paths per hour diagram. And is it still feasible if PP are granted and built in full.



  • Registered Users, Registered Users 2 Posts: 4,348 goingnowhere
    ✭✭✭




  • Registered Users, Registered Users 2 Posts: 2,810 AngryLips
    ✭✭✭


    In light of the disaster of the recent timetable changes, is this just pie in the sky aspirational stuff here?



  • Advertisement
  • Registered Users, Registered Users 2 Posts: 4,348 goingnowhere
    ✭✭✭


    They are only putting 3 trains an hour into GCD to terminate, thats a lot more realistic than the current timetable(s)

    No use of the link from the Northern Line to the new Spencer Dock station is interesting



  • Registered Users, Registered Users 2 Posts: 19 LastCall


    Wouldn't there be sufficient demand for 2-3 trains per hour to travel from Malahide to Maynooth via Spencer dock.

    Trains drive into Spencer Dock, and then the driver switches to the rear cab and it becomes the front end for the trip to Maynooth.

    As someone who lives on the Maynooth line, even 2 direct northerly trains per hour would be amazing.

    Rail experts, is this technically feasible under the Dart Plus plan?



  • Registered Users, Registered Users 2 Posts: 744 loco_scolo
    ✭✭✭


    The Spencer Docks plans only include a single alignment connection from the Northern line into Spencer Dock. Not sure why they've done that, but that's what's in the plans.

    Given this, having trains travel that direction would create conflicts between North Strand junction and Clontarf Road, while trains wait for a clear path.



  • Registered Users, Registered Users 2 Posts: 248 PlatformNine
    ✭✭


    Ah thats really interesting. I like that they plan on sending some Maynooth services to Bray, though I am surprised if they are doing that, they aren't sending at least one HH past GCD.

    I hope 4 tph to Greystones includes one going to Wicklow town., I think 4 tph of just Greystones services would mean 7 minute paths through Bray head? Which even with all the upgrades we might see around Bray head, I feel like 7 minute paths is insane unless they plan on some adding more upgrades then what was mentioned in the last study.

    I think its interesting that they plan on having ALL Drogheda DARTs running to Bray, but it makes sense if they can use regen braking to charge the batteries as much as possible before having them go to Drogheda. Also I do find the Drogheda-Laytown service funny, I understand why its there and hopefully it will show there is capacity for 6 tph of just DART services.



  • Registered Users, Registered Users 2 Posts: 19 LastCall


    Why is there 1 hourly Drogheda Laytown service? Can't image demand would be high for an hourly service. Perhaps more if a Betty'stown station was built.



  • Registered Users, Registered Users 2 Posts: 248 PlatformNine
    ✭✭


    Ah sorry, should have said why they are doing it. It is meant to be a trial service to prove Drogheda has capacity for 6 DARTs per hour. If all goes well it could mean 6 DARTs to/from Drogheda rather than 5, though if I had to guess it would probably replace one of the Malahide or Clongriffin services. I don't know if it will be possible to run that frequency before OHLE are installed, it depends on the charging capacity at Drogheda, either way it is good for them to test 6tph before throwing at it and hoping it works.



  • Registered Users, Registered Users 2 Posts: 15,518 loyatemu
    ✭✭✭✭


    It says 3/4 per hour to Greystones. Only 3 per hour alternating in each direction will be possible even with the planned passing loop. Possibly they plan to run 2 in a row in one direction at rush hour which already happens with Dart and Commuter/IC.



  • Registered Users, Registered Users 2 Posts: 248 PlatformNine
    ✭✭


    I assumed 3/4 means the 4th train would be run back-to-back with a Greystones service. My point was more that I hope they aren't hoping to attempt 4 paths per hour per direction, and use 3 as the backup plan. The diagram was made 2 years after the upgrade report which I believe still only allowed for 3 paths per hour per direction reliably. However I just assume the 4th train, ran back-to-back with a Greystones service, would be the hourly Wicklow town service. It doesn't show the Wicklow service on the diagram, but I think it's the only time to feasibly schedule it without otherwise extending one of the 3 Greystones services.

    However I did notice that diargram shows Rosslare services ending at Greystones, which I believe with the upgrade could technically make 4 paths per hour per direction possible. However I think ending Rosslare services in Greystones isn't a good solution, and even then I still don't think 4 paths per direction is practically possible. There just isn't enough room for error.



  • Registered Users, Registered Users 2 Posts: 15,518 loyatemu
    ✭✭✭✭


    Wexford trains currently run straight behind or before a Dart, so removing them doesn't really allow extra bidirectional services.



  • Registered Users, Registered Users 2 Posts: 248 PlatformNine
    ✭✭


    Practically? no it doesn't make enough of a difference and 6 paths per hour and 3 per direction is the way to go. However in terms of number, the gap between the two back-to-back trains is still a few minutes(shortest I found was 4 minutes), and above 6 paths per hour a few minutes is a massive difference. With the improvements from the report the single track section is supposed to take 5 minutes, which technically makes a 7 minute path possible if each path is a single train. But if a second train tries to use the same path then it would need at minimum a 10 minute path. Removing the back-to-back service technically makes it possible to get 7 minute paths and 4tph per direction possible.

    All that said, 7 minute paths for a 5 minute travel time is not practical. It's such a small difference that 4tph per direction is possible in the same way the August 26th timetables were possible. Its technically possible with the changes, but practically it only takes a small delay before everything falls apart. Thankfully after that disaster I doubt they will try something that insane again.



  • Advertisement
  • Registered Users, Registered Users 2 Posts: 15,518 loyatemu
    ✭✭✭✭


    they still haven't published the plan for Greystones/Wicklow, but I don't think they're implementing the full Jacobs report. The recent presentation to (I think) Engineers Ireland showed just a passing loop south of the tunnels. Everything else I've seen suggests 3 tph is their target. They're barely able to manage 2tph at the moment despite there being loads of leeway in the timetable. I see myself spending a lot of time sitting in that passing loop in the future (if they have it built before I retire).



  • Registered Users, Registered Users 2 Posts: 4,348 goingnowhere
    ✭✭✭


    Greystones/Wicklow wasn't in the plan at all, it was tacked on by politicians later



  • Registered Users, Registered Users 2 Posts: 4,348 goingnowhere
    ✭✭✭


    Bray Greystones supports 5tph currently, reliability is poor as any delay breaks things

    The 'plan'

    Shorten platforms, 1+3 at Bray to ~170m+90m

    Fit a crossover in from platform 1 to 3 and this gives 2 tracks through Bray station, currently there is a short single track section at the end of platform 1 which holds up trains

    Build a second track between tunnel 4 and the first road bridge at Greystones, close the level crossing with an underpass

    Post edited by goingnowhere on


  • Registered Users, Registered Users 2 Posts: 9,301 SeanW
    ✭✭✭


    In the UK they mainly have catenary-diesel and catenary-3rd rail changeovers to worry about, and the catenary is always 25kv AC at 50hz (excluding the Tyne and Wear Metro around Newcastle Upon Tyne). These types of changeovers can easily be done in stations: have the train raise or lower its pantograph while stopped at the station. A change between different voltages on catenary wire is always going to involve a short "dead" section between the two, although I think there are some border stations on the European mainland where the voltage delivered to catenary can be switched, so that "local" trains from either side of the border can go into the station.

    If hypothetically the entire line from Dublin to Belfast were to be electrified with a mixture of voltages/currents, IMO the most likely outcome would be dead section on some flat stretch of line just North of Drogheda with 1500VDC below that and 25kv AC at 50hz North of that.

    It is very practical to do it this way, in North America for example the Amtrak services on the North East Corridor between Washington DC and Boston change voltage and frequency many times during the journey (all between different voltage/frequency of AC on catenary) while local services like New York's Metro North Railroad New Haven Line changes from 3rd rail DC to overhead wire AC at Pelham - and trains run through that changeover at speed.

    https://u24.gov.ua/
    Join NAFO today:

    Help us in helping Ukraine.



  • Registered Users, Registered Users 2 Posts: 2,810 AngryLips
    ✭✭✭


    How does switching at Drogheda affect the prospoects of future commuter services to north Drogheda?



  • Registered Users, Registered Users 2 Posts: 2,361 KrisW1001
    ✭✭✭


    Any such DART services would have to be operated by dual-voltage EMUs, or by battery EMUs, as the core DART stock would be unable to run on the 25 kV railway. This isn't really a downside, as at for a Drogheda-Dublin all stops service, the regular DART trains would not be suitable, and it could be served using inter city EMUs.



  • Registered Users, Registered Users 2 Posts: 248 PlatformNine
    ✭✭


    https://www.nationaltransport.ie/news/iarnrod-eireann-unveils-first-train-of-brand-new-dart-fleet/

    The first new DART set has been assembled and is about to begin testing! The NTA published an article that has a good bit of detail, including some technical specs!



  • Registered Users, Registered Users 2 Posts: 1,474 p_haugh
    ✭✭✭


    DART+ Coastal South

    Connolly to Greystones

    Emerging preferred option being developed

    Public consultation commences early 2025

    Also contains confirmation that the public consultation for Dart+ Costal South (or what remains of it) being pushed back yet again.



  • Registered Users, Registered Users 2 Posts: 15,518 loyatemu
    ✭✭✭✭


    it's always just around the corner. Ann Graham told Wicklow councillors just a few weeks ago that it would be in November.



  • Advertisement
  • Registered Users, Registered Users 2 Posts: 232 scrabtom
    ✭✭


    I was just thinking about the amount of development that is planned for the Dart + South West corridor over the coming year. Between Adamstown, Clonburris, the City's Edge stuff, the Railworks at Inchicore and the LDA stuff at Heuston (which I'm a bit dubious about), there'll probably be about 100k more people living along the corridor within the next 20 years.

    Interesting to think about, and good to see us making use of our transport infrastructure to facilitate development in the right places.



Welcome!

It looks like you're new here. Sign in or register to get started.
Advertisement