A New Rail Line Along M1?

I dunno about the route , but the existing Dublin-Belfast rail line is pretty constrained , both by geography,and commuter trains ,

Could you get from heuston to the airport in heavy rail , and then off up to Belfast ?

I imagine it will be just like the layout on the M1 from Junction 14 to Junction 16 where the railway runs adjacent to the motorway (Tho the railway predates the motorway here obviously)

This saves in land severance and roads tend to elevated to cross the motorway which could help a bit. Also ground conditions, utilities are better understood.

There are a few examples of high speed lines with motorways across Europe, the French A5 for about 90kms and the Belgian A3 for much of its length and probably loads more. The gubermint should get the ball rolling on this one asap.

Not impossible, expensive probably

You'd need to swap out a lot the bridges to bridges like these:

I presume the line (if using the centre median would run from just beyond where the M1 crosses the Broadmeadow Estuaru at Lissenhall, having run cross-country through Kinsealy and west of Swords (tie in station with Metrolink at Estuary before joining the M1…?) and continue all the way to before the Toll at Drogheda…? I see this as being very doable with only a short tunnel/viaduct (realistically a cutting with a small bridge for getting between the two lanes is much easier) needed at each exit point from the carriageway, land that is already owned by TII/The Govt.

The only question is how would it tie in to Drogheda Station? Ideally it wouldn’t, and would continue to follow the M1 on a new DOUBLE TRACK (the current Boyne Viaduct is only single track) bridge over the Bohne estuary outside of Drogheda before joining the mainline around Sandpit? A new station could be built here and half of the Drogheda DARTS could continue on to connect with Enterprise Services here? (Potential for a bit of Transit Orientated Development here also…) How many people get a train from Drogheda to beyond Dundalk (Dundalk commuters would presumably run alongside DARTs on the regular existing line so no change form the regular Drogheda - Dundalk part of the service here), and how much would it put them out to have to get a DART one stop north and then get another train to continue their journey…? Could a Drogheda West station also be built after the Boyne crossing?

I really feel that bringing the newly built line back into the current Drogheda station could take away from a lot of the benefit of it, as having a segregated newly built high speed section gets more beneficial the more of it you have, and the Boyne viaduct is potentially a big capacity killer. The tight curves needed to get from the M1 to a point on the current Northern Line where a junction can be made, also pose an issue to the project and will slow down services and also be more expensive to build (far more land to CPO than if you did the tie in north of Drogheda, and the land south of Drogheda is more populated too). Just some thinking out loud really, but I’d never thought of an M1 rail line before and it really seems like a nobrainer!

We can`t 4 track the existing line and Connolly is too congested anyway. A rail line from Heuston Station utilising the Phoenix Park tunnel and maybe the old cement depot in Cabra as a station before bending down to travel along the side of the M1 to the airport before continuing a new alignment out to the North Co Dublin. Then you can work out the Drogheda issue but there is no point sorting the Boyne viaduct before dealing with the requirements of heavy rail to the airport and 4 track capability to Connolly

https://www.irishtimes.com/transport/2024/10/09/irish-rail-to-unveil-plans-for-new-tracks-through-north-dublin/

Interesting that this covered in the IT today

Irish Rail is planning to double the number of tracks on its northern route out of Dublin from two to four.

The plan, which Irish Rail chief executive Jim Meade said he hoped would be published by early next year, involves separating Dart and commuter services from the Dublin to Belfast services, similar to the four-track railway approach to Dublin city from the west.

“We believe this [four-track approach] needs to be replicated north of Connolly Station, ideally between Connolly and Malahide, and this ambition is also included in the All-Island Strategic Rail Review,” he told the Oireachtas transport committee on Wednesday.

While this would be good, the problem here is the inability (without a complicated reversal on a very crowded section of rail) to get from Heuston itself, into the PPT. And while I’d be the first to say that a heavy rail line to the airport is a good thing, I don’t think that the most effective way to do it is to tunnel all the way under north Dublin, dangerously close to the Metrolink tunnel, with no direct access from either of the main rail terminals

Quad tracking Clongriffin to Connolly is not impossible as well and is something very likely to happen in the not-so-far future and in fact, something that is needed anyway. It is a goal of IÉ and was specifically outlined in the AISRR which also looked at a new completely segregated (and underground in the GDA, like you’re suggesting here) line between Dublin and Drogheda/Belfast and deemed that the benefits were not worth the cost.

Stations may have to be rebuilt and moved similar to the Kildare Route Quad Tracking but realistically, much of the route is in slanted cuttings which with the addition of retaining walls could be turned into retained cuts with vertical walls and as a result, much more space at track level, so it is not impossible at all.

An airport spur would likely run from Clongriffin, along the express Enterprise alignment for a few kms before splitting and diving for the airport on the eastern approach. Much cheaper as the land here is on the airport flight approach.

The DARTs that serve the airport here could run express from Clongriffin to Connolly or Spencer Dock (and on to Hazelhatch) on the fast lines, similar to a Stansted or Heathrow Expresses in London, which with a train let’s say every 15/20 minutes, would have minimal effect on the 3 other non stop tph on the fast lines (hourly Enterprise and twice hourly Dundalk commuters)

And with Rosslare/Wexford trains being diverted to Heuston, Sligo trains likely to Spencer Dock, and most northern, southwestern, and western commuter services now through-running as DART services through Connolly’s platform 5,6, and 7, a single platform being used for a half hourly airport shuttle (the other two tph would ideally go through DU) shouldn’t have too adverse an affect on Connolly capacity.

This way both Connolly and Heuston get a connection to the airport with minimal extra infrastructure (just a spur off the at-this-stage-already-completed M1 line and Quad tracked Northern Line)

Quad tracking the northern line is as I said, both strongly recommended in the AISRR and a development goal of IÉ I do believe, and if the M1 rail line is to happen (the only sensible way to build a new ‘fasttrack’ Enterprise route) then a quad tracked NL is needed. An airport spur from this would really be minimal in the grand scheme of things and if added to the one big super project of two extra tracks from Connolly to Drogheda (via the M1) would really only add to the projects benefits, especially from a general public’s point of view, specifically benefitting the rest of the country with a link to Dublin Airport moreso than Dubliners whom the Metro would be better suited to.

I have also considered this and think that it’s a much less complicated (and therefore easier, cheaper, and faster to execute) plan, however a new line alongside the M1 with a Boyne Viaduct bypass has far more benefits for what I can’t see being much of a bigger price tag - the line being implemented along the motorway on lands already government-owned. Honestly I don’t think there’s much in it as to which project progresses but what is clear is that 2 extra tracks are undoubtedly needed between Connolly and Drogheda.

I'm hoping for 4 tracking from Dublin Connolly out as far as Malahide at least.

Putting tracks on the motorway is not going to happen. That space is going to be needed to add a 3rd lane for traffic sooner rather than later.

A second northern line totally separated would be amazing. But I can't see it happening in my life time.

A spur from Clongriffin / Balgriffin to Dublin airport, should have happened years ago, but I believe it'll be hard now (or hugely expensive) , as quite a lot of that land was built on :(

The missed opportunty - 4 line metro tunnel with 2 heavy rail from donabate to liffey junction. Then option of train going to Heuston/ connolly/ Spencer Dock. 10b cost would have rose 20b assuming no economies of scale.

Connecting North and south west to Dub Airport with one direct train you start to see significant shift in car journeys to airport.

Its not a bad idea but it would likely just be VERY expensive for little benefit. And I don't like to say that as I think PT should first and foremost be about connectivity and reliable transport rather than cost efficiency, but there is a line in which something gets so unbelievably expensive that it gets hard to justify.

Even the regular D+ Tunnel/D underground/cross dublin tunnel (or whatever its called now) gets close to that because of how expensive it is. For context the AISRR lists the D+ Tunnel as being the single most expensive thing it reccomends. The difference being is the D+ Tunnel will eventually become impossible to avoid as the city expands, or at least the route itself will either as heavy rail or as another metro line.

So how many stations / stops would you envision on an M1 rail link ? Dublin airport probably , And heading on north , a stop outside Drogheda , but not outside Dundalk ? ,I assume there'd be a stop near Newry ?

Ideally no additional stops however possibly there would be one in Swords as the alignment will be going through it, either along side the M1 the whole way, or through Seatown East and over the Estuary before running alongside the M1. I think it would be difficult to get permission run a rail alignment through or next to Swords without a stop, however a public consultation might reveal otherwise.

The idea of the M1 alignment is to get Enterprise(and by extension Dundalk) services out to Drogheda as quickly as possible with little to no congestion from DARTs. So the Alignment would leave from Connolly, by then likely four tracked, through Clongriffin before heading west and running along the M1 before connecting back into the existing line before Drogheda (or as other have proposed after Drogheda to bypass the Boyne viaduct). The final solution for Drogheda will likely need a few studies and some public consultation before making a final decision. Specifically for Drogheda Enterprise alightments and boardings, as well as cost/feasibility on routing around Drogheda vs through Drogheda and potentially twin-tracking the Boyne viaduct. Eitherway though, it would rejoin the existing alignment well before Dundalk.

I don't think there is a good way of getting this alignment to the airport, though 1-3km of the alignment might be shared with the airport link (ideally not of course). To get people to the airport with the new M1 alignment would either mean having to turn around trains in the airport station, which would mean long dwell times which would defeat the purpose of the alignment. Or they would have a station far enough away that it would require a people mover or shuttle, which wouldn't serve very well as an airport link. Niether are ideal solutions and I think the best option is to not try and use the new alignment as an airport link.

Would it be possible to quad track from Connolly to near the airport ?

Is there much point in an alignment doesn't go to the airport ?

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…

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

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

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 ?

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.