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Track formations - to excavate or not?

Discussion in 'Civil Engineering M.I.C.' started by Rail Rover, Dec 3, 2017.

  1. Rail Rover

    Rail Rover New Member

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    Hi All,

    I'm from the Yorkshire Wolds Railway near Driffield in East Yorkshire. We will soon be relaying 'the next field' from our existing site in the direction of Wetwang.

    The next field is one of only two in a couple of miles where the old formation (compacted chalk) has been excavated & the field has been returned to arable crops. The others are grasses for grazing, being a few inches of top soil over the formation, so much easier.

    As part of our grant application we have planned to get the next field's formation reinstated at considerable cost. However, various sources have recommended not actually putting the formation back, but more a half-way house of skimming the surface, putting a membrane down & laying grades of ballast on that. Some railways have used this method (we have visited) but some say we'll be forever repacking it! It would of course be much cheaper. I can't envisage our axle weights realistically exceeding 20T; we're only at 10T currently.

    Your opinions would be welcome, please.
     
  2. Ploughman

    Ploughman Part of the furniture

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    Skim off as much as possible and extend out at least 1.8m from the sleeper ends,graded too a crossfall of 1 in 30 across the full width.
    La y a membrane across full width of the formation and then apply 150mm of ballast.
    Ballast to about 750mm from sleeper ends the remainder of the open width use chippings or gravel as a cover and weed suppressant and walking / access route in a cess.
    You may get away with slightly less depth at 100mm but I would go for 150mm if possible.

    Are you likely to need to install a drainage system?
    Or is existing field drainage OK?

    What rail and sleepers are you liable to be using?
    Or is it a case of whatever is available?

    Best of luck anyway.
     
  3. Rail Rover

    Rail Rover New Member

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    Many thanks Bryan. You seem to speak from experience!

    Drainage should be OK. Despite the next field being slightly lower than those at either side, the ground is predominantly chalk. so reasonably free draining.

    Most of the track will be bullhead on hardwood sleepers.
     
  4. Ploughman

    Ploughman Part of the furniture

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    Just an added comment.
    Below the membrane should be a layer of Stone about 100 - 150mm thick.
    Something like Highway Grade, Type 1 limestone or equivalent, rolled and graded to the required crossfall.
     

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