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The future of the Bray-Greystones line

  • 29-04-2019 7:44pm
    #1
    Moderators, Entertainment Moderators, Science, Health & Environment Moderators Posts: 13,233 Mod ✭✭✭✭ marno21


    This came up in the Luas for Bray line and I thought it merited its own topic.

    The single track constraint south of Bray is clear at present and is only going to get worse as Greystones seems to be expanding unabated, the M11/N11 is at breaking point and the single track nature of the line severely constrains services along the route.

    Here's a thread for discussing this as it's not covered by the proposed DART Expansion project.


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Comments

  • Moderators, Computer Games Moderators, Recreation & Hobbies Moderators Posts: 9,211 Mod ✭✭✭✭ CatInABox


    Don't know how it can be fixed without a major project to provide a second tunnel/double tracking, and I just can't see that happening anytime soon, if ever. There was talk of them looking into putting a passing loop just after the tunnel, but I can't see much space there myself.


    Getting the most out of what is there though, that's something that could happen. Having the commuter trains stop at Bray, the passengers get off and walk across the platform to a waiting Dart would allow the train to return south, more than doubling the frequency of the trains to the south. Wouldn't even increase the journey time for most commuters really, as they get stuck behind the Dart anyway, particularly now that it's gone to a ten minute service.


  • Registered Users Posts: 323 ✭✭ Ireland trains


    The only way with current infrastructure would be to have a dart in greystones that leaves when another one comes in.
    Frequency would be 3tph.

    Or just run some darts to greystones really early and run them back later in morning peak and then in evening peak run a few trains to greystones and have them immediately follow behind a dart as far as bray sidings


  • Closed Accounts Posts: 13,993 ✭✭✭✭ recedite


    have a dart in greystones that leaves when another one comes in.
    Frequency would be 3tph.
    Indeed. Its not exactly rocket science.


  • Registered Users Posts: 15,803 ✭✭✭✭ LXFlyer


    The only way with current infrastructure would be to have a dart in greystones that leaves when another one comes in.
    Frequency would be 3tph.

    Or just run some darts to greystones really early and run them back later in morning peak and then in evening peak run a few trains to greystones and have them immediately follow behind a dart as far as bray sidings
    recedite wrote: »
    Indeed. Its not exactly rocket science.

    Running a single track railway at 100% occupancy leaves no resilience for delays and is completely impractical.

    Scheduling for a railway is far more complicated than you might think.

    There is already a split signal mid-route which does allow for a train to follow another in the same direction, and it does see use with the Rosslare & Gorey services following the DART services in either direction, but that's really the only scope for the operation.


  • Registered Users Posts: 5,154 ✭✭✭ prunudo


    The other far more worrying aspect of the route is the coastal erosion just north of Wicklow at the Murrough, every easterly storm erodes more and more of the shoreline. The cynic in me would say that it suits IE not to invest a huge amount in the line as it's only a matter of time before nature claims the track.


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  • Closed Accounts Posts: 13,993 ✭✭✭✭ recedite


    LXFlyer wrote: »
    Running a single track railway at 100% occupancy leaves no resilience for delays and is completely impractical.
    There's no reason (excuse) for delays if one is waiting there to leave whenever another one comes in.


  • Registered Users Posts: 15,803 ✭✭✭✭ LXFlyer


    recedite wrote: »
    There's no reason (excuse) for delays if one is waiting there to leave whenever another one comes in.

    OK I'll make this simple for you.

    If a DART is scheduled to leave Bray at xx:00 and then arrives in Greystones at xx:09, and then another DART is scheduled to leave Greystones immediately at xx:10 and arrive at Bray at xx:19, and then a southbound DART scheduled to leave Bray at xx:20 and arrive in Greystones at xx29, and so on for a full 60 minutes, what do you do at any point if the southbound DART is late arriving into Bray, as inevitably will happen?

    There is no resilience built into that kind of schedule and it would be impossible to operate without cancelling trains, as delays can and do happen.

    You simply cannot operate on a single track railway without having some inbuilt recovery. That's basic in rail operations planning. You can't work on 100% occupancy.


  • Closed Accounts Posts: 13,993 ✭✭✭✭ recedite


    LXFlyer wrote: »
    If a DART is scheduled to leave Bray at xx:00 and then arrives in Greystones at xx:09, and then another DART is scheduled to leave Greystones immediately at xx:10 and arrive at Bray at xx:19, and then a southbound DART scheduled to leave Bray at xx:20 and arrive in Greystones at xx29, and so on for a full 60 minutes, what do you do at any point if the southbound DART is late arriving into Bray, as inevitably will happen?
    That (late) train waits for the next 10 minute slot, or else the passengers disembark and wait for the Greystones train to arrive, while the empty train returns northbound.
    Not a big deal for passengers who are already well used to getting off and waiting 30 minutes.


  • Registered Users Posts: 8,229 ✭✭✭ LeinsterDub


    LXFlyer wrote: »
    OK I'll make this simple for you.

    If a DART is scheduled to leave Bray at xx:00 and then arrives in Greystones at xx:09, and then another DART is scheduled to leave Greystones immediately at xx:10 and arrive at Bray at xx:19, and then a southbound DART scheduled to leave Bray at xx:20 and arrive in Greystones at xx29, and so on for a full 60 minutes, what do you do at any point if the southbound DART is late arriving into Bray, as inevitably will happen?

    There is no resilience built into that kind of schedule and it would be impossible to operate without cancelling trains, as delays can and do happen.

    You simply cannot operate on a single track railway without having some inbuilt recovery. That's basic in rail operations planning. You can't work on 100% occupancy.

    And that allows no time for intercity units either


  • Registered Users Posts: 15,803 ✭✭✭✭ LXFlyer


    recedite wrote: »
    That (late) train waits for the next 10 minute slot, or else the passengers disembark and wait for the Greystones train to arrive, while the empty train returns northbound.
    Not a big deal for passengers who are already well used to getting off and waiting 30 minutes.

    Sorry, but that kind of approach to scheduling flies in the face of all good practice and guidelines.

    You don't design a service that is going to inevitably have mass cancellations as your approach would have.


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  • Registered Users Posts: 176 ✭✭ specialbyte


    There are some potential changes that could be made to the Bray to Greystones line that would allow for increased frequency. There is roughly 7km of single track between Bray and Greystones.

    One small option is to double track the bridge over Putland Road in Bray. Now you've added 400m of double track to your system (look where the points for the single track start). A small change for a small improvement but and improvement none the less.

    The biggest possible improvement would come from double tracking from Greystones to south of the tunnel. It's roughly 2.3km. Even if you didn't double track all it but you just added a passing loop in the green fields you'd be able to get more out of the line.

    There's potentially 2.7km of the 7km, or ~40% of the line that is potentially double trackable without going near the tunnel or the cliff. You'd get significant improvements with that. You'll never be able to run a high frequency service but if you were able to get every 15-20 minutes that would be a game changer for Greystones.


  • Registered Users Posts: 15,803 ✭✭✭✭ LXFlyer


    There are some potential changes that could be made to the Bray to Greystones line that would allow for increased frequency. There is roughly 7km of single track between Bray and Greystones.

    One small option is to double track the bridge over Putland Road in Bray. Now you've added 400m of double track to your system (look where the points for the single track start). A small change for a small improvement but and improvement none the less.

    The biggest possible improvement would come from double tracking from Greystones to south of the tunnel. It's roughly 2.3km. Even if you didn't double track all it but you just added a passing loop in the green fields you'd be able to get more out of the line.

    There's potentially 2.7km of the 7km, or ~40% of the line that is potentially double trackable without going near the tunnel or the cliff. You'd get significant improvements with that. You'll never be able to run a high frequency service but if you were able to get every 15-20 minutes that would be a game changer for Greystones.

    You’re quite correct.

    The only practical method of increasing the DART frequency between Bray and Greystones throughout the day is to install additional track work; and a passing loop south of the tunnels is the most likely option.


  • Registered Users Posts: 2,902 ✭✭✭ Vic_08


    LXFlyer wrote: »
    You’re quite correct.

    The only practical method of increasing the DART frequency between Bray and Greystones throughout the day is to install additional track work; and a passing loop south of the tunnels is the most likely option.

    I don't think a passing loop would be good enough, a full double track from Greystones to the first tunnel portal and a re configuring of the lines south of Bray as far as the Putland Road single track bridge to make them double running lines might just be enough for a workable 20 min frequency.

    This would reduce the siding space south of Bray which would create operational/stabling challenges.

    Doubling Putland Rd bridge and extending double track onto Bray head would make a 20 min frequency more resilient but how far along the head is possible without major engineering is an issue. There is no way to do more than 20 min frequency without a full double tracking and the only practical way to do that is a separate full bored tunnel away from the sea which would be very expensive.


  • Registered Users Posts: 15,803 ✭✭✭✭ LXFlyer


    It’ll all boil down to funding.

    There has already been a study on this by IE some time ago and a plan for a passing loop but funding was never forthcoming. That did propose a 20 min frequency if I recall correctly.

    Now the NTA are reinventing that wheel so we will see what happens.


  • Registered Users Posts: 13,369 ✭✭✭✭ loyatemu


    BusConnects says there will be a 20 minute frequency; the NTA are currently looking into how to provide it. There is space for a loop between the long tunnel and the minor level-crossing at the Grove but that would require fairly tight scheduling (not something IÉ are renowned for).

    Doubling all the way to the station is a much bigger job but they're going to have to spend some money, Greystones is rapidly expanding, so are Kilcoole and NewtownMK and the road options are poor. In the medium term a second tunnel is going to be necessary, they could look at the engineering requirements for that now (possibly this is included in the current NTA study)


  • Registered Users Posts: 15,803 ✭✭✭✭ LXFlyer


    loyatemu wrote: »
    BusConnects says there will be a 20 minute frequency; the NTA are currently looking into how to provide it. There is space for a loop between the long tunnel and the minor level-crossing at the Grove but that would require fairly tight scheduling (not something Iare renowned for).

    Doubling all the way to the station is a much bigger job but they're going to have to spend some money, Greystones is rapidly expanding, so are Kilcoole and NewtownMK and the road options are poor. In the medium term a second tunnel is going to be necessary, they could look at the engineering requirements for that now (possibly this is included in the current NTA study)

    The original BusConnects network plan said a lot of things that frankly were off the wall, and will have to change, not least due to the recent frequency increases on many routes.

    I wouldn’t be relying on that at all at this stage, and specifically in this case given that it will involve significant work to provide the infrastructure to enable such a frequency to operate - that won’t happen in 12-18 months.


  • Registered Users Posts: 1,207 ✭✭✭ Rashers72


    Would not rely on IE/NTA to progress installing a passing loop. 7-8 years ago a developer built an entire station for IE at Clongriffin. They installed full platforms for 2 passing loop yet by now only 1 was installed. And then in Sept they went and deployed 10 min DARTS which killed punctuality and reliability on Northern suburban line, especially in morning peak. Would have allowed much greater contingency etc. But 7 years later we are still waiting. I gather IR never even applied to NTA to fund it, despite being 1/2 built.


  • Moderators, Science, Health & Environment Moderators Posts: 17,125 Mod ✭✭✭✭ Sam Russell


    Rashers72 wrote: »
    Would not rely on IE/NTA to progress installing a passing loop. 7-8 years ago a developer built an entire station for IE at Clongriffin. They installed full platforms for 2 passing loop yet by now only 1 was installed. And then in Sept they went and deployed 10 min DARTS which killed punctuality and reliability on Northern suburban line, especially in morning peak. Would have allowed much greater contingency etc. But 7 years later we are still waiting. I gather IR never even applied to NTA to fund it, despite being 1/2 built.

    I thought Clongriffin was part of the plan for IR to extend Dart to the airport. When that was knocked on the head, Clongriffin was left as is.

    Likewise, there was some work at Pearse anticipating the DU. Same story.


  • Registered Users Posts: 8,229 ✭✭✭ LeinsterDub


    Rashers72 wrote: »
    Would not rely on IE/NTA to progress installing a passing loop. 7-8 years ago a developer built an entire station for IE at Clongriffin. They installed full platforms for 2 passing loop yet by now only 1 was installed. And then in Sept they went and deployed 10 min DARTS which killed punctuality and reliability on Northern suburban line, especially in morning peak. Would have allowed much greater contingency etc. But 7 years later we are still waiting. I gather IR never even applied to NTA to fund it, despite being 1/2 built.

    IE's issue is the loop line bridge. They are quite frankly running out of capacity


  • Registered Users Posts: 323 ✭✭ Ireland trains


    A DART branch to the airport is a no-brainer especially with dublin airport now having over 30 million passenger a year.
    Also would have a more even flow of traffic throught the day


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  • Moderators, Science, Health & Environment Moderators Posts: 17,125 Mod ✭✭✭✭ Sam Russell


    A DART branch to the airport is a no-brainer especially with dublin airport now having over 30 million passenger a year.
    Also would have a more even flow of traffic throught the day

    It is also relatively cheap. 7 km across open countryside, with a few bridges - I think €100 million to €200 million was . If it was done before Metrolink, it would be in service quickly, and could be planned to fit in with Metrolink at the airport.

    As for Bray Greystones, they could reposition the TBM after it finished the ML tunnel, to do its bit for Bray to Greystones.


  • Moderators, Entertainment Moderators, Science, Health & Environment Moderators Posts: 13,233 Mod ✭✭✭✭ marno21


    A DART branch to the airport would be a colossal waste of money. Metrolink will serve the airport, the Northern Line is constrained enough and so is the Connolly area without blowing €300m on a second airport link with no capacity additions south of Howth Junction


  • Moderators, Science, Health & Environment Moderators Posts: 17,125 Mod ✭✭✭✭ Sam Russell


    marno21 wrote: »
    A DART branch to the airport would be a colossal waste of money. Metrolink will serve the airport, the Northern Line is constrained enough and so is the Connolly area without blowing €300m on a second airport link with no capacity additions south of Howth Junction

    Where did the €300 million figure come from?

    The Dart extension was on the assumption that DU would go ahead. Also Howth Junction to Howth would become a shuttle service which could become driverless. Current schedule is 9 minutes Howth to Howth Junction. If a 10 min service could be achieved, that would make it more useful.

    The Dart Airport link could be built quite quickly, and in service long before ML, by maybe 4 or 5 years. If ML was extended to Donabate, then Dart/Airport would not serve those coming from north of Malahide, and but the Dart/Airport would serve those north of Connolly going to the airport.

    There are 50,000 workers at the airport, many living in north Dublin, and they need to get to work. Train is the most appropriate way.


  • Moderators, Entertainment Moderators, Science, Health & Environment Moderators Posts: 13,233 Mod ✭✭✭✭ marno21


    Where did the €300 million figure come from?

    The Dart extension was on the assumption that DU would go ahead. Also Howth Junction to Howth would become a shuttle service which could become driverless. Current schedule is 9 minutes Howth to Howth Junction. If a 10 min service could be achieved, that would make it more useful.

    The Dart Airport link could be built quite quickly, and in service long before ML, by maybe 4 or 5 years. If ML was extended to Donabate, then Dart/Airport would not serve those coming from north of Malahide, and but the Dart/Airport would serve those north of Connolly going to the airport.

    There are 50,000 workers at the airport, many living in north Dublin, and they need to get to work. Train is the most appropriate way.
    Apologies, it's actually €200m it was costed at in 2011 but you can add a bit onto that for increases since.

    I'd be in favour of this being left off the table until at least Metro North/South + DART Underground are complete. A second airport rail link is to me down the priority list until those three are complete.

    It's also not in the 2016-2035 GDA Transport Strategy so is officially off the table for the near future anyway.


  • Registered Users Posts: 13,369 ✭✭✭✭ loyatemu


    maybe a thread for the Dart airport link?


  • Registered Users Posts: 8,229 ✭✭✭ LeinsterDub


    It is also relatively cheap. 7 km across open countryside, with a few bridges - I think €100 million to €200 million was . If it was done before Metrolink, it would be in service quickly, and could be planned to fit in with Metrolink at the airport.

    As for Bray Greystones, they could reposition the TBM after it finished the ML tunnel, to do its bit for Bray to Greystones.

    2 trains per hour would be a pretty poor service and add a long delay to those not going to the airport or would you propose just running a shuttle service?


  • Moderators, Science, Health & Environment Moderators Posts: 17,125 Mod ✭✭✭✭ Sam Russell


    2 trains per hour would be a pretty poor service and add a long delay to those not going to the airport or would you propose just running a shuttle service?

    Why would it be a 30 min service? If there is the traffic, then the trains will run it. The traffic to and from he airport is more evenly spread throughout the day, and the Howth service becoming a shuttle would allow at least a 20 min service. It would be possible to make the Malahide service a 30 min service and the airport to be a 15 min service. It could also have an express non stop service into the CC.

    Build it and it will be a success.


  • Moderators, Motoring & Transport Moderators, Technology & Internet Moderators Posts: 20,995 Mod ✭✭✭✭ bk


    We are much more likely to see MetroLink extended to meet the Northern Rail line then the other way around.


  • Registered Users Posts: 8,229 ✭✭✭ LeinsterDub


    Why would it be a 30 min service? If there is the traffic, then the trains will run it. The traffic to and from he airport is more evenly spread throughout the day, and the Howth service becoming a shuttle would allow at least a 20 min service. It would be possible to make the Malahide service a 30 min service and the airport to be a 15 min service. It could also have an express non stop service into the CC.

    Build it and it will be a success.

    Capacity issues . A shuttle service would work .


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  • Registered Users Posts: 13,369 ✭✭✭✭ loyatemu


    bk wrote: »
    We are much more likely to see MetroLink extended to meet the Northern Rail line then the other way around.

    they should be planning that already (at Donabate) - it's a no-brainer IMO

    The dart spur was a bad plan - it wouldn't have been any quicker than existing bus services, only serves the airport and connects into an already congested line.

    If the northern line could be upgraded then there might be a case to run some/all services via an airport spur (with a grade separated triangular junction), but a Metrolink extension could serve the same purpose if they added Donabate as a stop for the Enterprise.


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