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Technical Rail Query - Catch Points ???

Comments

  • #2
    GerardKeating
    Registered Users, Registered Users 2 Posts: 7,805 ✭✭✭GerardKeating


    steamengine wrote: »
    I am curious as to the exact purpose of these points, as denoted by the green arrow. Are they catch points, trap points or a combination of both ? Are they there to protect the main line or to prevent runaway rolling stock careering down the bank, or again both ? The location is the East Wall Bank and the Dublin - Belfast line is shown just above the bank.

    http://maps.google.ie/maps?q=53.357237,-6.237949&hl=en&ll=53.357245,-6.237924&spn=0.000287,0.001073&sll=53.357168,-6.237934&sspn=0.000379,0.001073&num=1&t=h&z=20

    In the dim distance past (pre-electrification) I think there was "more" to the junction, a link to the (now removed) siding you can see in the photo.


  • #3
    foggy_lad
    Closed Accounts Posts: 20,373 ✭✭✭✭foggy_lad


    GerardKeating wrote: »
    In the dim distance past (pre-electrification) I think there was "more" to the junction, a link to the (now removed) siding you can see in the photo.
    To me(no expert) it looks like the junction was originally different with a shorter distance and a wider angle but at some later stage the junction was made faster by having the angle between the lines reduced and the overall length of the junction increased. It looks like the original junction could have joined where the third line strouts away from the other two. Hope that makes sense as I can't see any green arrows etc.

    These points are then left in place because they are used while the work is ongoing and it would take even more disruption to remove them.


  • #4
    steamengine
    Closed Accounts Posts: 2,372 ✭✭✭steamengine


    That looks like it could the answer ok - thanks guys !!!


  • #5
    Hungerford
    Registered Users, Registered Users 2 Posts: 912 ✭✭✭Hungerford


    foggy_lad wrote: »
    These points are then left in place because they are used while the work is ongoing and it would take even more disruption to remove them.

    They look like trap points to me. If you consider the direction of travel on the line, it looks like they might be there to derail any runaways before they got onto the main line.


  • #6
    foggy_lad
    Closed Accounts Posts: 20,373 ✭✭✭✭foggy_lad


    Hungerford wrote: »
    They look like trap points to me. If you consider the direction of travel on the line, it looks like they might be there to derail any runaways before they got onto the main line.
    But if you look at the distances between these points and the junction points any runaway is going to plough into the main lines anyway, if they were trap points wouldnt they be derailing away from any oncoming trains?


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  • #7
    Hungerford
    Registered Users, Registered Users 2 Posts: 912 ✭✭✭Hungerford


    foggy_lad wrote: »
    But if you look at the distances between these points and the junction points any runaway is going to plough into the main lines anyway, if they were trap points wouldnt they be derailing away from any oncoming trains?

    I suppose that it's either that or derail them into West Road. Plus the path of any derailed train would be the various pieces of debris between the two sets of lines.


  • #8
    steamengine
    Closed Accounts Posts: 2,372 ✭✭✭steamengine


    These points appear to have the capability of de-railing where the movement is ascending the bank, e.g. a train leaving the docks northbound. That is the way it looks from the DART. I assume catch points would be placed lower down the gradient, so it looks like a choice between trap points and an old truncated set of points, no longer in use. Trap points physically preventing unauthorised movement on to the mainline would make sense. I would be more in favour of this explanation - but I'm no expert either.


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