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Luas and O/H wires

  • 31-03-2015 6:46pm
    #1
    Sam Russell
    Moderators, Science, Health & Environment Moderators Posts: 20,153 Mod ✭✭✭✭


    How far can a Luas tram go without overhead wires?

    I was in France recently and was surprised to see their tram system running with no overhead wires across a large square - distance about one km. What happens is the tram, just before it sets off, folds or raises its pantograph and then runs on batteries (either that or the driver pedals like hell:D).

    It would be useful for the stretch between Jervis to Abbey and so O'Connell Street is clear of overhead wires.

    Any ideas?


Comments

  • #2
    crc
    Registered Users, Registered Users 2 Posts: 74 ✭✭crc


    In Bordeaux they have certain central sections with a hidden third rail in the ground. It's more expensive, but they justified it on the basis of aesthetics in the old part of the city. I don't think they use batteries, but other cities might.
    http://en.wikipedia.org/wiki/Ground-level_power_supply


  • #3
    Sam Russell
    Moderators, Science, Health & Environment Moderators Posts: 20,153 Mod ✭✭✭✭Sam Russell


    There was no third rail on the one I saw. The tram might be going slower though, but that might have been an unwillingness to run down the numerous jay walkers.

    I think it is a recent tram system, and the trams look just like Luas ones.


  • #4
    Aard
    Registered Users, Registered Users 2 Posts: 4,905 ✭✭✭Aard


    Nice? Tbh I never noticed that there were no overhead wires over Massena and Garibaldi until somebody pointed it out. The trams would also take a few moments to lower the yokes safely into the roof. Not hugely worth it imo, but some people have very strong views on the matter.


  • #5
    Victor
    Registered Users, Registered Users 2 Posts: 78,580 ✭✭✭✭Victor


    Sam Russell wrote: »
    There was no third rail on the one I saw.
    It's concealed underground to stop killing the jay-walkers.


  • #6
    L1011
    Registered Users, Registered Users 2 Posts: 71,184 ✭✭✭✭L1011


    Sam Russell wrote: »
    There was no third rail on the one I saw. The tram might be going slower though, but that might have been an unwillingness to run down the numerous jay walkers.

    I think it is a recent tram system, and the trams look just like Luas ones.

    It's inductive, it's dear and it's unreliable


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  • #7
    Sam Russell
    Moderators, Science, Health & Environment Moderators Posts: 20,153 Mod ✭✭✭✭Sam Russell


    Aard wrote: »
    Nice? Tbh I never noticed that there were no overhead wires over Massena and Garibaldi until somebody pointed it out. The trams would also take a few moments to lower the yokes safely into the roof. Not hugely worth it imo, but some people have very strong views on the matter.

    Yes, Nice. There are no underground rails or secret inductive coils or anything like that - think what that would do for the keys in your pocket!

    The tram obviously runs on batteries.

    How far can it do that for? I think it would work for Jervis to Abbey, and also for the new line going up O'Connell street.


  • #8
    GerardKeating
    Registered Users, Registered Users 2 Posts: 7,806 ✭✭✭GerardKeating


    Sam Russell wrote: »
    I think it would work for Jervis to Abbey, and also for the new line going up O'Connell street.

    Not really, then none of the existing LUAS trams could use that section of track.


  • #9
    L1011
    Registered Users, Registered Users 2 Posts: 71,184 ✭✭✭✭L1011


    Sam Russell wrote: »
    secret inductive coils or anything like that - think what that would do for the keys in your pocket!

    Nothing, that's what. Its one of the few varying systems used for ground-level power in pedestrian areas.

    The sectional power system used in Marseilles breaks when it rains so it's out. The conduit collector system gets full of litter so its out.

    None of them are reliable, none of them are cheap and all exist to satisfy argumentative councils and little else.


  • #10
    GerardKeating
    Registered Users, Registered Users 2 Posts: 7,806 ✭✭✭GerardKeating


    L1011 wrote: »
    Nothing, that's what. Its one of the few varying systems used for ground-level power in pedestrian areas.

    The sectional power system used in Marseilles breaks when it rains so it's out. The conduit collector system gets full of litter so its out.

    None of them are reliable, none of them are cheap and all exist to satisfy argumentative councils and little else.

    Maybe I am a bit naïve, but why not a small battery/capacitor/flywheel/magic dust to allow travel over short powerless sections?


  • #11
    L1011
    Registered Users, Registered Users 2 Posts: 71,184 ✭✭✭✭L1011


    GerardKeating wrote: »
    Maybe I am a bit naïve, but why not a small battery/capacitor/flywheel/magic dust to allow travel over short powerless sections?

    Weight and complexity.

    It can be, and is done (there's entirely flywheel operated tramcars in the UK used on some very low traffic train lines) though. However I don't see the grave need for it in Dublin - there were wires on far more streets for ~50 years in the past for trams anyway.


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  • #12
    Sam Russell
    Moderators, Science, Health & Environment Moderators Posts: 20,153 Mod ✭✭✭✭Sam Russell


    GerardKeating wrote: »
    Not really, then none of the existing LUAS trams could use that section of track.

    Do you know that for a fact?

    It must be such that trams can be moved without O/H power so they can move to safety in the event of a power failure or the O/H line falling. How far can they move? The distance I saw was about 1 km. The trams I saw running without O/H wires were very close to the same as the ones used for Luas.

    They have taken down the O/H wires in O'Connell street for some parade or other a while back.


  • #13
    GerardKeating
    Registered Users, Registered Users 2 Posts: 7,806 ✭✭✭GerardKeating


    Sam Russell wrote: »
    Do you know that for a fact?

    Yes, if the power is interrupted, they come to an immediate/complete stand still.
    Sam Russell wrote: »
    It must be such that trams can be moved without O/H power so they can move to safety in the event of a power failure or the O/H line falling. How far can they move?
    They could use another type of vehicle to tow them.
    Sam Russell wrote: »
    The distance I saw was about 1 km. The trams I saw running without O/H wires were very close to the same as the ones used for Luas.

    As mentioned earlier in this thread, those trams have a secondary power source for this, which is hidden from view.
    Sam Russell wrote: »
    They have taken down the O/H wires in O'Connell street for some parade or other a while back.

    Are you sure about this, I remember the first year of the Luas, there was a big fuss about it, and Luas said a big NO.


  • #14
    Sam Russell
    Moderators, Science, Health & Environment Moderators Posts: 20,153 Mod ✭✭✭✭Sam Russell


    Maybe secondary power is an optional extra.

    The Becket bridge is designed for trams, maybe they will require this as the bridge opens.


  • #15
    Sam Russell
    Moderators, Science, Health & Environment Moderators Posts: 20,153 Mod ✭✭✭✭Sam Russell


    Wikipedia has something on this.
    Power supply
    Nice tramway was originally to use the ground-level power supply third rail system as used by Bordeaux tramway. However, this was abandoned in favour of the more conventional overhead power supply cables providing 750V DC, except where the tram crosses the Place Masséna and Place Garibaldi, when it lowers its pantograph and relies on its onboard nickel metal hydride batteries to cross these large open spaces, where overhead wires would be an eyesore.[7]

    This could work well from Jervis to Abbey, and along O'Connell St. This would make the crossover easier.

    Obviously, retro fitting batteries might be expensive for the existing trams, but would be OK for new ones. Both tram systems are made be Alstrom.

    http://en.wikipedia.org/wiki/Nice_tramway


  • #16
    L1011
    Registered Users, Registered Users 2 Posts: 71,184 ✭✭✭✭L1011


    Sam Russell wrote: »
    Do you know that for a fact?

    It must be such that trams can be moved without O/H power so they can move to safety in the event of a power failure or the O/H line falling. How far can they move?

    Zero metres.

    Disabled trams are either towed out by another tram or one of the two diesel mini-locos (Unilok, built in Tuam). There is a coupler at each end under a lifting plate IIRC.

    4627590390_6d03f67aef.jpg


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