A New Rail Line Along M1?

DrivingSouth

I would think as a principle any new track being laid in the GDA should be 4 track, just for future proofing. Or is that overkill?

Note the exception would be the mini spur bridge/tunnel from the M1 to the airport.

OisinCooke

https://www.boards.ie/discussion/comment/122724115#Comment_122724115

DU is an exception as well, wherever that happens but everything (countrywide in fact) should definitely be either built doubled or have space for the upgrade at the very minimum. Space and CPO costs seem like an obvious hamperer of quad track space however and although I agree with the sensibility of the idea in the GDA, I think it could only make projects like this even further out of reach…

PlatformNine

https://www.boards.ie/discussion/comment/122722175#Comment_122722175

If there was an airport train I would think it would operate through Clongriffin as a normal DART service(or at least limited stop) before going to the airport, I think it would be good to have some "airport express" services through out the day but I don't think it makes any sense to have all airport services operate like that as that mostly defeats the purpose of it over ML. At the very least it would need to stop in Clongriffin. I didn't consider a grade separated crossing for the airport link and the M1 alignment, which I have to say is quite funny because in my head the fast lines of the four-track would be to the east and cross over the slow lines with a grade separated crossing after Clongriffin, so I don't know why I never thought of that.

I agree that ideally there shouldn't be a station in Swords for the sake of the Enterprise services. And even if there is a station the Enterprise itself should't stop in Swords for exactly the reasons you say, only maybe Dundalk services or a dedicated Swords services(or Swords-Clongriffin shuttle). But again I think it could be a case of "it would be difficult to get permission for an alignment through Swords without a station." I really hope public consultation reveals otherwise though, has having a dedicated IC line I think is much better overall and needed.

But I do think the only reason the station is feasible is because of how close to Dublin it is, even without three- or four-tracking. It should only take around 5 minutes to get to Clongriffin, where it could either switch to the slow track and continue on to Connolly or Spencer Dock, or to Clongriffin as a Shuttle. And because it only would serve the one staiton outside of dublin it likely wouldn't need high frequency, 4tph per direction at most (for now at least). The other option is if a Swords station is really needed for approval and to try and minimise Enterprise and Dundalk services needing to slow down, is to make it a small branch off of the M1 alignment (heavily dependent on how its routed of course). The branch would likely be the most expensive of any option, but would also allow a heavy rail interchange with ML without slowing down the M1 alignment. Ideally of course none of this is a concern and there is not the demand or the call for a Swords stop.

I will add though, ideally while CPOing land for the alignment, they would hopefully plan for a future four-tracking if the need to run commuters along the alignment becomes needed. Especially for what will become such a vital corridor for IC services.

OisinCooke

https://www.boards.ie/discussion/comment/122725669#Comment_122725669

Something that could be done is that the airport station could be built on a loop, as done off many of the ICE lines in Germany to serve airports they run close to. This way you wouldn’t need DARTs only to necessarily to serve a one station branch to the airport but could incorporate that (along with a four-tracked station at Estuary) into the Dundalk commuter services. Have a grade separated flying junction to and from the airport and problem more or less solved…?

I also agree that for this corridor (one through central Dublin) it is a great idea to at the time CPO for four tracks - it would only be an extra few metres either side - and while I can’t necessarily see the need for 4 tracks outright, with stations at the airport, Estuary, and potentially more TODs north of Dublin, along with hourly (potentially half hourly in the peak) services to Belfast and eventually Derry, the line quickly gets quite crowded and while a double track line with four track ‘passing’ stations works for a line with one or two stops, once you add more stops, you just need the 4 tracks.

And yes I would absolutely have any DART Airport Express services call at Clongriffin to make changes from other services much easier. The diagram I was thinking would be 4 trains per hour - two expresses from Connolly every 30 minutes, and 2 all-station-stopping services from Hazelhatch via DU every other 30 minutes. All would call at Clongriffin before peeling off for the airport and maybe Estuary where turn back facilities could be provided if DARTs only went that far and Dundalk commuters went further, however it may make more sense to begin with having all of the airport DARTs go from Hazelhatch and run far more frequently - ie. the service through DU would be an airport DART every 10 minutes.

With a 10 minute frequency on Drogheda - Connolly/Bray services as well though would the slow lines on a quad-tracked Northern Line have the capacity for a train every 5 minutes…? And depending on what side the tracks were on, a flying grade-separated junction may be needed at North Strand to access the tunnel, UNLESS the portal emerged at the back of Clontarf Golf Club (much easier albeit more expensive to do now that IÉ have shot themselves in the foot regarding Spencer Dock

PlatformNine

https://www.boards.ie/discussion/comment/122729104#Comment_122729104

Thats fair, I just think an airport station could easily meet the capacity of 4tph alone, let alone if other stops were introduced on the branch. My main gripe however with the airport station not being the terminal station is that it would likely make the branch far more expensive than it will already be. Having it be the terminal station at least allows it to go straight in and out of the airport (either elevated or underground). But for it to continue on to another station further north either will need it to turn around if it is still a bay platform station, or like you say, a loop line which would greatly increase costs.

Ah that makes more sense, 2tph express and 2tph full stop would work quite nicely. I am personally not accounting for DU in my ideas just because I don't like to view plans being dependent on each other unless they have to be (for example M1 alignment only improves so much without four-tracking Connolly-Clongriffin, though with DART to drogheda that might not be the case anymore). But accounting for DU that is a good plan. I will say though, with ML, western services likely good better serviced by PPT services at Glasnevin rather than going all the way to Connolly.

I believe the current plan for D+ north is already includes 5 min frequency or 12tph on Connolly-Clongriffin per direction, 9 DARTs, 2 Dundalk Commuters, and 1 Enterprise. Four tracking would further increase the capacity along the line though likely most if not all of the 12tph on the northern slow-line would be used for DARTs, and a lot of the time inbetween them used for passing and terminating Maynooth and HH services. I wasn't considering track capacity, so yes it would be contrained, likely the fast-line would need to get used for airport services, especially if they are not calling at all stations.

I will add quickly, I am confused about whether DU surfacing at SD is still an option or not. The D+ west planning report does make some references to DU surfacing at SD, however I am not sure if any of them are remotely indate. Looking at the building plans, it doesn't seem impossible although it wouldn't be easy.

dowlingm

The thing people have to bear in mind about motorway shared alignments is vertical and horizontal curvature is significantly more permissive even for high speed motorways. This can then mean complex construction where the road is at grade and the rail is zipping in and out of bridges and cuttings/tunnels. It’s not completely impractical of course, depending on terrain - look at Dunleer-Dundalk where the M1 runs parallel to the rail.

If the Boyne viaduct route was no longer carrying the full load towards Dundalk/NI then you could look at having some trains on the coastal line take the spur towards Slane and Navan, instead of or in addition to the M3 route

PlatformNine

https://www.boards.ie/discussion/comment/122824999#Comment_122824999

I doubt the idea/plan was and hopefully will never be to route the alignment curve-for-curve or slope-for-slope with the M1, just that generally it would be closer to the M1 and would run along side when possible. While I think the M1 route itself might allow for a new 145kmh alignment, I'm not sure if it would allow an alignment capable of closer to 200kmh. Which I think having an alignment not capable of the speeds would partially defeat the purpose of the alignment. Though we don't really know what IE is discussing behind the scenes, and we likely wont until they get consultation on the alignment. Hopefully that will happen sooner than later as their does seem to be some will to do it.

Markcheese

In real terms with a stop at Dublin airport - or starting from Dublin airport , and next stop at Drogheda ,how much of a difference would it make traveling at 145 kph v 200 kph ?

Markcheese

Its only 40km, so that's 30mins in a car .. but it takes longer to speed up and slow down ,

In theory you could also follow the route of the M2, if the terrain suited better ?

There isn't any extra stops on the way anyway to Drogheda,

PlatformNine

https://www.boards.ie/discussion/comment/122874283#Comment_122874283

I wouldn't assume this alignment would additionally serve as an airport link, there just isn't a good way of doing it without making the alignment very expensive and/or adding a long dwell time to the alignment. The later of which partially defeats the purpose of the alignment.

However Looking from Connolly to Drogheda, the current route is scheduled to take about 35 minutes. It's really difficult to say, but if I had to take a guess the new alignment alone would shorten Connolly-Drogheda by about 10 minutes, and increasing the speed to 200km/h might shorten the trip by another 5 minutes, maybe a little more.