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The Northern Line Problem

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  • 26-06-2020 8:53pm
    #1
    ncounties
    Registered Users Posts: 270 ✭✭


    We all know that the Northern Line is constrained by the fact that it is predominantly double track, whilst DART, Enterprise and Inter-City/Commuter services all utilise the line.

    The solution that has been banded about for years is four tracking the existing line, but even then these plans normally only look at the immediate Dublin area, and don't account for the fact that DART services could one day soon, go all the way to Drogheda.

    We also know that plans for improving speeds to Belfast are also banded about. But how can this be achieved in the years ahead with a twisting victorian railway line, that in time, will share up to third of its length with regular, frequently stopping, commuter services. Rail users from Dundalk and Drogheda will equally suffer on trips going into Dublin City Centre.

    So, I got my money spending crayons out again. What if we scrapped the idea of quad tracking. Instead, we built a new alignment from South of Drogheda at Colp, that went, as far as possible, on a relatively straight alignment to the airport. Then from the airport, we tunnel, single bore, under the existing port tunnel, exiting at a portal in Clontarf Golf Club. Then we ensure the remaining line to Connolly is quad tracked. This would be 40km of new line, and 8km of tunnel.

    Further improvements in time could be carried out on the alignment between Drogheda and Dundalk, and straightening the alignment between Newry and Lisburn (via Banbridge). It would also allow capacity for services to Armagh, Derry and Omagh if a rail line is ever reinstated there.

    Finally, if the DART interconnector were to be rehashed, we could potentially look at allowing for additional capacity to enable services from Cork, Limerick and Galway to go onwards to the new Dublin Airport station. All the while the coastal route can be left to serve the local populations along its length more frequently than it would be in the current circumstances.


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    #2
    strassenwo!f
    Registered Users Posts: 1,512 ✭✭✭strassenwo!f


    While there might be some interaction of such a scheme with the port tunnel at the airport end, there should be none at the other end: emerging in or near Clontarf Golf Course would mean that your line is overground by Clontarf Road, and thus would already be above ground as it crosses the southern end of the port tunnel.

    A problem with your proposal to stick Cork/Galway/etc trains into a DART Underground tunnel might be that such trains would need to be running on electricity, in some way. This could mean electrification of those intercity lines (highly unlikely) or improvements in battery technology. It's doubtful that this is insurmountable, but I would prefer to see the Dart Underground's potential used for commuter trains (almost) exclusively. The numbers of passengers emanating from Cork/Limerick/etc who wish to go to/from the airport probably don't justify direct trains and the associated hassle/inefficiencies in a cross-city tunnel.


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    #3
    ncounties
    Registered Users Posts: 270 ✭✭ncounties


    Fair point re-electrification. I also agree that with current services, and plans, Cork/Galways/Limerick services would be a hinderance in the proposed DART interconnector. But given, it will probably the best part of 30 years before we see it in place, surely the plans could be reviewed in that time.

    There are lots of bus services from these cities to Dublin Airport, I am sure if we built the infrastructure, the passengers would defect to rail, whilst we'd also be able to entice a larger proportion of car drivers. But that was just an idea to further justify the spend on tunnelling from Clontarf to the airport. I really think this could be a better option than quad tracking the Northern line.


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    #4
    Carawaystick
    Registered Users Posts: 8,779 ✭✭✭Carawaystick


    Its 33-35 mins by enterprise from Dublin to Drogheda, how many minutes would 40km of new track save? vs quadtracking?

    How would NIR trains use the tunnel?

    The money would be better spent getting the line speed up from 25mph around Poyntspass for intercity journey time reductions.


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    #5
    ncounties
    Registered Users Posts: 270 ✭✭ncounties


    Carawaystick wrote: »
    Its 33-35 mins by enterprise from Dublin to Drogheda, how many minutes would 40km of new track save? vs quadtracking?
    The Covid-19 timetable states it takes 30mins, but the line is known for regular delays. The new line could bring that down to the region of 20mins with increased reliability, whilst allowing for a stop at Dublin Airport.

    But the advantage is not limited to simply speed improvements on this segment, it's also improve capacity, allowing for additional services on the line. Additionally, it improves the reliability of services, and with a stop at the airport, furthers demand/attractiveness of the services which operate along it.
    How would NIR trains use the tunnel?
    Through DMU traction - which has been muted for the Enterprise service in the past. Better yet, EMUs if the line was ever fully electrified.
    The money would be better spent getting the line speed up from 25mph around Poyntspass for intercity journey time reductions.
    I agree, improvements should be made along the line's entire length. But with increased DART services (which I welcome), comes decreased capacity for intercity/town services.


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    #6
    SeanW
    Registered Users Posts: 8,740 ✭✭✭SeanW


    Good idea overall, putting the Northern commuter and Enterprise services on their own alignment that directly connects with the Airport would be great. The only thing is though you'd need to use only hybrid or fully electric trains at any underground stations. You'd need that at the airport and most likely new underground intercity platforms as well, I suspect that finding a place for the tunnel to come to surface in town would be difficult.


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    #7
    ncounties
    Registered Users Posts: 270 ✭✭ncounties


    SeanW wrote: »
    Good idea overall, putting the Northern commuter and Enterprise services on their own alignment that directly connects with the Airport would be great. The only thing is though you'd need to use only hybrid or fully electric trains at any underground stations. You'd need that at the airport and most likely new underground intercity platforms as well, I suspect that finding a place for the tunnel to come to surface in town would be difficult.

    Ah yeah, I didn't consider the the engines running whilst in the underground station. Ideally the whole line, all the way to Belfast, would go electric.


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    #8
    Carawaystick
    Registered Users Posts: 8,779 ✭✭✭Carawaystick


    Not increasing the tracking on the existing northern line leaves the same congestion issues
    and gives those living far away from Dublin easy access, while those living near, the same or worse access.
    This is already the case with getting to the Airport by PT, theres more services from Donegal to the airport than from most Northside suburbs


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    #9
    ncounties
    Registered Users Posts: 270 ✭✭ncounties


    Carawaystick wrote: »
    Not increasing the tracking on the existing northern line leaves the same congestion issues
    and gives those living far away from Dublin easy access, while those living near, the same or worse access.
    This is already the case with getting to the Airport by PT, theres more services from Donegal to the airport than from most Northside suburbs

    How exactly does taking all intercity/commuter rail services off the tracks to free them up for only DART services, and quad tracking Clontarf to Connolly leave the current Northern Line with the same current congestion levels?

    I know we don't do rail properly in this island, but generally in other European countries, Intercity services travel faster than city rail services.


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    #10
    LXFlyer
    Registered Users Posts: 17,542 ✭✭✭✭LXFlyer


    Your proposal doesn't really solve a lot regarding capacity on the Northern Line, as it only helps with trains from Drogheda and north of that point (Belfast Enterprise and trains serving Dundalk/Drogheda).

    That's not that many trains. The Enterprise is only ever going to be hourly at max.

    You still have to have the same levels of semi-fast outer suburban DART service along the Northern Line calling at all the stations between Clongriffin/Malahide and Laytown which are the stations that the vast majority of Northern Line passengers are using. Those semi-fast DARTs will remain slow as they are unable to overtake an inner DART service that is calling at all stations between Connolly and Howth Junction. That is where the capacity issue is worst.

    To solve that, the only realistic (and cost effective) solution is to provide (through either three tracking or preferably quad tracking) the ability to overtake along the section between Clontarf Road and Raheny (buildings are too close to the permanent way around Kilbarrack/Howth Junction), a southbound loop at Clongriffin, and additional turnback facilities and loops where possible to maximise the use of line capacity north of Clongriffin.


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    #11
    LXFlyer
    Registered Users Posts: 17,542 ✭✭✭✭LXFlyer


    To explain that further - a train overtaking a stopping DART between Connolly and Clontarf Road will have to slow behind the previous DART further along the line.

    Having the overtaking further out means it is possible to overtake and keep line speed (trains can already overtake between Connolly and Suburban Junction).


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    #12
    ncounties
    Registered Users Posts: 270 ✭✭ncounties


    LXFlyer wrote: »
    Your proposal doesn't really solve a lot regarding capacity on the Northern Line, as it only helps with trains from Drogheda and north of that point (Belfast Enterprise and trains serving Dundalk/Drogheda).

    That's not that many trains. The Enterprise is only ever going to be hourly at max.

    You still have to have the same levels of semi-fast outer suburban DART service along the Northern Line calling at all the stations between Clongriffin/Malahide and Laytown which are the stations that the vast majority of Northern Line passengers are using. Those semi-fast DARTs will remain slow as they are unable to overtake an inner DART service that is calling at all stations between Connolly and Howth Junction. That is where the capacity issue is worst.

    To solve that, the only realistic (and cost effective) solution is to provide (through either three tracking or preferably quad tracking) the ability to overtake along the section between Clontarf Road and Raheny (buildings are too close to the permanent way around Kilbarrack/Howth Junction), a southbound loop at Clongriffin, and additional turnback facilities and loops where possible to maximise the use of line capacity north of Clongriffin.

    Why was development ever allowed to take place at St Berach’s Place. That development looks less than 20 years old.


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    #13
    D.L.R.
    Registered Users Posts: 1,282 ✭✭✭D.L.R.


    Nice idea, but much cheaper to quad the northern than tunnel under it.


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