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Dublin Metrolink - alternative routes

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  • Last Stop wrote: »
    This would require the tracks in the tunnel to be stacked. This option was looked at as part of the tunnel configuration study for Metrolink and Dart underground but they chose single bore side by side for Metrolink so if you’re tying into that at Stephens Green you need the same tunnel configuration.

    Not really. The tracks can twist between different configurations over the length of the single bore tunnel. Think of it like a length of 4” drainpipe with two lengths of flexible 2” water pipe inside. the water pipes can be side by side at one end and stacked at the other.




  • Not really. The tracks can twist between different configurations over the length of the single bore tunnel. Think of it like a length of 4” drainpipe with two lengths of flexible 2” water pipe inside. the water pipes can be side by side at one end and stacked at the other.

    To do that would require a single bore tunnel high enough to accommodate both tracks. Given that the plan was to upgrade the green line, it is assumed that Metrolink will have overhead cables rather than third rail meaning you’d need at least 5m head room for each track plus the depth of track meaning a tunnel diameter greater than the 10m roughly Metrolink is proposing.
    It is possible in theory but not on this project.




  • Not really. The tracks can twist between different configurations over the length of the single bore tunnel. Think of it like a length of 4” drainpipe with two lengths of flexible 2” water pipe inside. the water pipes can be side by side at one end and stacked at the other.

    That would require the height and widths allowed per tram to be the same. You’ve over simplified it.




  • Dublin was recently added to the list of capitals that will suffer from flooding on a regular basis due to rising sea levels. To even contemplate building a subterranean transport network given that threat would be foolish in the extreme. I stand by what I said before, Dublin will not get a metro system.




  • reg114 wrote: »
    Dublin was recently added to the list of capitals that will suffer from flooding on a regular basis due to rising sea levels. To even contemplate building a subterranean transport network given that threat would be foolish in the extreme. I stand by what I said before, Dublin will not get a metro system.

    A full flood risk assessment will be completed as part of the planning application.
    If Amsterdam can build a metro despite being below flood level, I think Dublin will be fine.


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  • salmocab wrote: »
    That would require the height and widths allowed per tram to be the same. You’ve over simplified it.

    It’ll all fit in an 11.7m single bore tunnel easily enough.




  • reg114 wrote: »
    Dublin was recently added to the list of capitals that will suffer from flooding on a regular basis due to rising sea levels. To even contemplate building a subterranean transport network given that threat would be foolish in the extreme. I stand by what I said before, Dublin will not get a metro system.

    Metro does not have to be underground, could be elevated (like the DART loop line)




  • Metro does not have to be underground, could be elevated (like the DART loop line)

    Apart from the unsightlness of that it makes turning in the city around street corners almost impossible it also increases the length of the thing, I would say it’s a complete non runner.




  • You can make a metro station pretty much any width you want. Just stack the platforms. There is no law that says the tracks have to run side-by-side.

    Indeed.

    For example, much of the U4 in Frankfurt is like this. It was built under large stretches of the Berger Strasse, which is often about as wide as Liffey Street.




  • It’ll all fit in an 11.7m single bore tunnel easily enough.

    Which is still bigger than the proposed Metrlink tunnel


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  • reg114 wrote: »
    Dublin was recently added to the list of capitals that will suffer from flooding on a regular basis due to rising sea levels. To even contemplate building a subterranean transport network given that threat would be foolish in the extreme. I stand by what I said before, Dublin will not get a metro system.


    Sea level rises is panning out to be much less than expected. Just read any articles about it from 20 years ago. Current rises are not a major worry.




  • Bdjsjsjs wrote: »
    Sea level rises is panning out to be much less than expected. Just read any articles about it from 20 years ago. Current rises are not a major worry.

    Unless you live in Dublin City or Cork City. Just 5 metres sees me, and much of Dublin City, under water.

    I do not think that the Metrolink tunnel would be a particular problem as it will be designed properly to cope. The bigger problem is with water and wast ware infrastructure.




  • Last Stop wrote: »
    Which is still bigger than the proposed Metrlink tunnel

    Have they stated what tunnel diameter it is intended to use?

    It seems more likely that the promoters will increase the diameter or use twin-bore, than that they will build a station at Camden St.

    (A stacked configuration at Dunville Avenue would seem like it would make it a lot easier to later link to the Luas line on the narrow site.)




  • reg114 wrote: »
    Dublin was recently added to the list of capitals that will suffer from flooding on a regular basis due to rising sea levels. To even contemplate building a subterranean transport network given that threat would be foolish in the extreme. I stand by what I said before, Dublin will not get a metro system.

    The BART in San Francisco actually goes beneath the ocean in some places. The technology exists to prevent flooding.

    Not building it would be even more foolish.




  • Unless you live in Dublin City or Cork City. Just 5 metres sees me, and much of Dublin City, under water.

    I do not think that the Metrolink tunnel would be a particular problem as it will be designed properly to cope. The bigger problem is with water and wast ware infrastructure.
    Models that predict 5 m sea level rise assume a vast increase in pace of rise. At the moment sea level rise is in the milimeters.




  • Have they stated what tunnel diameter it is intended to use?

    It seems more likely that the promoters will increase the diameter or use twin-bore, than that they will build a station at Camden St.

    (A stacked configuration at Dunville Avenue would seem like it would make it a lot easier to later link to the Luas line on the narrow site.)

    Looking like 9.2m external diameter. This report also explains why mono tube was ruled out (cost and waste)
    Beechwood station (at Dunville Ave) was cut and cover from tunnel portal. To build a stacked station here would have added significantly to the cost and green line closure.

    https://www.metrolink.ie/assets/downloads/MetroLink_PR_Design_Development.pdf#page32




  • Last Stop wrote: »
    Looking like 9.2m external diameter. This report also explains why mono tube was ruled out (cost and waste)
    Beechwood station (at Dunville Ave) was cut and cover from tunnel portal. To build a stacked station here would have added significantly to the cost and green line closure.

    https://www.metrolink.ie/assets/downloads/MetroLink_PR_Design_Development.pdf#page32

    That cut and cover station might be built stacked though. I have not seen a plan for how they intend to eventually join these lines without requiring an extended disruption to the service. The stacked configuration whether in a TBM tunnel or in cut-and-cover facilitates a narrower footprint. It also allows use of sharper gradients at the portal which may result in a shorter footprint too




  • How could you go from a single bore tunnel to a stacked station in a couple of hundred metres? The gradient on the upper level would be huge and then you’d still have issues with actually tying into the green line.
    The issues would arguably be bigger as you’d go from tracks at the same level to tracks at different levels and then back to tracks at the same levels

    The two biggest problems with the green line tie in are the tunnel portal and the station upgrade. A stacked station solves neither of these and arguably makes thinks worse.




  • Last Stop wrote: »
    How could you go from a single bore tunnel to a stacked station in a couple of hundred metres? The gradient on the upper level would be huge and then you’d still have issues with actually tying into the green line.
    The issues would arguably be bigger as you’d go from tracks at the same level to tracks at different levels and then back to tracks at the same levels

    .

    Put the tunnel-bound track on the lower level. The gradient downwards can be as sharp as you like as long as it is not unduly uncomfortable.




  • Put the tunnel-bound track on the lower level. The gradient downwards can be as sharp as you like as long as it is not unduly uncomfortable.

    Metros typically have a maximum gradient of 5%. Just because it’s downhill doesn’t mean that limit doesn’t apply. Anything over 5% and you’re into special requirements from rolling stock which drives up the cost.


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  • Last Stop wrote: »
    Metros typically have a maximum gradient of 5%. Just because it’s downhill doesn’t mean that limit doesn’t apply. Anything over 5% and you’re into special requirements from rolling stock which drives up the cost.

    What extra costs are there for trains that can run down steep grades?




  • What extra costs are there for trains that can run down steep grades?

    The design to handle a >5% slope. The rolling stock specifications will be based on the steepest gradient




  • Apology if this has been already mentioned here. Residents on the northside decided that Metrolink was going to start euthanasing the elderly while failing to count the blades of grass in a park.

    It really is quiet staggering the extreme level of NIMBY lunatics that public transport projects unleash in this country.

    https://www.dublininquirer.com/2019/11/13/some-residents-have-ideas-for-local-metrolink-station-they-just-wish-tii-would-listen




  • MrAbyss wrote: »
    Apology if this has been already mentioned here. Residents on the northside called the Garda after they decided that Metrolink was going to start euthanasing the elderly while failing to count the blades of grass in a park.

    It really is quiet staggering the extreme level of NIMBY lunatics that public transport projects unleash in this country.

    https://www.dublininquirer.com/2019/11/13/some-residents-have-ideas-for-local-metrolink-station-they-just-wish-tii-would-listen

    Not sure you read that right, GADRA is an acronym




  • Pity the church isn't being demolished. Horrendously ugly.

    Nimbys aren't the problem, you get nimbys everywhere. The problem is the state folding like a cheap suit every time some minor nimby nonsense comes up. Now its god's grass verge. Laughable.

    Ecuador just opened a metro folks. Ecuador.




  • Some residents say they’re worried that the area around it wouldn’t be able to cope with traffic during the construction period.

    The area wont be able to cope with the traffic it'll experience if they don't build it!




  • I really like the Luas.

    However, unless it is small spurs off existing lines, I think we need to think more along the lines of a 20-40 year plan for multiple underground metro lines across the city, alongside the DU and the original Metro West orbital style piblic transport.

    The Green line was (is?) a great piece of infrastructure, but only for a small number of people in Ranelagh, would be a fully fledged metro line within the next 7 or 8 years instead of remaining as is. Meanwhile, the Red Line is not a big enough piece of transport to serve the biggest suburb in the country, Tallaght, which is essentially a small city.

    The last few pages have shown how low our expectations for positive transport changes are. We nearly settle for scraps rather than properly believing we can do better. Some are annoyed that the residents of the sw part of the city dare to expect more for their area in their calls for a metro. Parish pump comments from people who probably won't benefit from a metro line in that area but know the current plans benefit them.

    I live on the northside but more power to the residents of the sw for puting pressure on their public reps to get a metro line out there.

    At the very least ALL residents of the city deserve a proper 20-40 year plan of proposed transport investment for ALL of the city, that is backed by all political parties. Some areas like the SW clearly deserve to be next in line, but we should all have a timeframe across the board and know the plans for our areas.

    Anyhow, I believe the Metrolink will be built and will be a great success and the above will end up happening, though I don't expect it to happen in my working lifetime.




  • Some are annoyed that the residents of the sw part of the city dare to expect more for their area in their calls for a metro.

    The reason I among others are annoyed is because the purpose of pushing for a Metro now is a means of stopping Bus Connects in that part of the City.




  • donvito99 wrote: »
    The reason I among others are annoyed is because the purpose of pushing for a Metro now is a means of stopping Bus Connects in that part of the City.

    Why not aim for something potentially better than Bus Connects?


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  • is the amount of traffic conflicts not the bigger issue for luas, rather than the length of the lines?


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