Stuff about ballast

Discussion in 'Tips & Tricks' started by Dave-the-Train, Oct 20, 2006.

  1. Over the next few days I'm going to try to post copies of some stuff i've posted elsewhere about ballast. I hope these notes will be useful.

    Apologies for not editing them into something consistant/logical in order... they took a bit of time to do in the first place.

    Hope they're useful :)

    Here's #1

    As someone who has walked on a lot of it I can tell you that ballast varies with location and age as well as regular (or irregular) maintenance.
    It also varies by source... different roads would get different ballast from different quarries. This means that the original material can vary significantly in colour... from pink through grey and white to green... blue probably gets in there somewhere. Slag based balast will tend to be black.
    That applies to new ballast.
    Once it's on the formation the local environment will influence the way the stone weathers... just the same as a stone building... put it in a smoky city and it will go black... countryside it may green... especially with a lot of trees around.
    What happens will also depend on how well drained the roadbed starts out and has remained. Wet beds are not the sole problem of parents.
    It takes time for weathering to impact the visual condition of ballast. During that time many things can happen...
    Coal, iron, phosphates and sand traffic can all leave spillage that gets into the ballast... in yards it may hide the ballast (and ties) completely.
    Spilled grain may also germinate... I've heard that this even happens on top of covered hoppers.
    Maintenance can also top up the ballast with new ballast... sometimes this is planned, sometimes surplus from a nearby planned job is run off where the local crew know they need it.
    Then there's modern ballast cleaning... the ballast lifted out, cleaned ... the rubbish sifted out... and the good stuff put back... this will have the changed (older) colour but the open grain of new ballast. .

    ..which introduces the point that new ballast is more open textured while older is both compacted and filled with crud... to put that technically "the interstices can become obstructed". The interstices in ballast are important for two reasons... they allow drainage and they allow the track formation to flex. Flexion is important... it allows a better ride and better traction. A solid road has all sorts of special problems. When this is a concrete roadbed (as in subways and some tunnels) the engineering is extremely specific. When ballasted track gets to be solid the permitted speed can be forced down to walking pace. I knew a location at which this occurred. The limit for all traffic was 2mph. When they came to repair the track they had to jack-hammer it out a lump at a time. Chalk had washed into the ballast, the drains became clogged... we got a mile of unplanned concrete.

    If you really want to get technical there's ballast that's recently been tamped... this shows hollows close to the ties and rails where the picks have been rammed in and worked.

    It is quite possible for one road to be old ballast while the adjacent road is brand new ballast. it is even more possible for one road to be cleaned / tamped while the adjacent road is old... it would not usuallly be new.

    Then you get lengths where hand maintenance has occured... this may include patches of new ballast... the run-off ballast may have been worked in or dumps of material spotted and then worked in... of course these dumps may also still be waiting for use.

    Okay... so then there's ballast that's been blown out of the quarry with gunpowder... which I haven't seen... dynamite... which I have... and modern explosives... which has cut my boots to bits...
    Dynamite and the subsequent further breaking and screening makes a ballast with the edges knocked off (Model that! scale) modern methods shatter the stone away almost to required size and it gets very little working... this means that it arrives in the track extremely clean, angular and sharp. It is often also extremely white and bright.

    AND that's not all... track can be cambered... but extremely few models need to include this.

    Oh yes... do you fill your ballast between the ties part way up the tie, to the top of the tie or higher? If higher does it also cover the ties ... or not. You could ridge the ballast... or form a V... this can be to the base of the tie, midway or deeper (deeper is one way of increasing drainage in special locations.

    Happy with that?

    Okay, so where does the ballast run to laterally? The tie ends...or how far beyond? What shape do you make the end? square, rounded or angled? These were discussed options.... what the stuff on the ground gets up to is a completely different issue... especially over time.

    In some places that I work at the moment the ballast outside the tie ends is formed into a continuous ridge. This is done by machines. I don't know the technical reason for it. It may be related to line speeds in excess of 100mph. Grading is now not only managed by lasers but with GPS. If you drop a clanger when replacing the computer bits you ca get very wiggly track... this is corrected by good old shovels pushed by men...
    When ballast cleaning or replacing... where does the spoil go?

    What do you get beyond both the tie ends and the ballast limit? We call the immediate area outside the ballast the "cess"

    The cess usually has some form of drain... varying from a basic ditch to elaborate drainage structures... which may be brick or concrete.

    In particularly wet locations drains may be obvious between the tracks as well as at the sides.

    In the
    pole lines are almost universally replaced by trunking. This was almost exclusively standard concrete sections but an increasing number of variants are appearing. The thing you need to ask yourself is "where are the telegraph lines, power lines etc". Before we went into troughing various conduits including wood and asbestos pipe (same stuff as corrugated asbestos) were used at various locations where overhead lines were not suitable... or kept getting knicked. I beleieve you have done something similar. ...especially in urban and industrial areas.

    Then there's different ties. I've seen something on full size plastic ties...\or they may have been recycled car tyres.

    Several things influence tie progression... what it is made of... which wood, which concrete (colour and size of aggregate) and how long it's been there in what conditions. With wood it will also depend on how it was originally treated... in the
    US that includes WHETHER it was treated far later than in the UK
    . Green wood was used much later... treating, especially pressure treating took time and cost more.... Also your track tends to remain unchanged on less economic lines far longer than ours does... most of ours got lifted in the '60sl

    Would you believe that the wood for ties was deliberately selected from different points in the felled timber? Then there could be a question whether it was laid heart side up or down. ties were not always cut square. Obviously ties from nearer the bark could have distinct shape changes but hey were also machined other than square. Some were half round... but very rapidly these were all laid flat side down. Lumber roads would use their own product... as far as possible the less saleable material... the more temporary the road the less work would be done to trim the timber... i.e. raw logs could be used. ... or, to get consistant thisckness they could be split or cut on two opposite faces... but not even de-barked on the remainder. Length was only significant when convenient.

    The main reason regular ties become standardised to a road is simply the convenience of standardisation... particularly in maintenance and tools/machines.

    There are two things to do...
    1. get out and look at it SAFELY!
    2. Study photographs and film extremely closely.

    With a little effort and practice you should be able to spot several different tyoes of ballast / track in quite a short time.

    Then again ... there's track in pavement...

    There's also grade crossings...

    There's switches...

    There's bridge track...

    There's track with guard (check) rails...

    there's track that is tied longitudinally (usually by rails in the four foot way)....
    are you all familiar with the 4'...6' and 10' ways (your dimensions - other than the 4' - may be different.... working from cess to cess you get...
    cess, 4' , (the bit the train body passes over), 6' or 10' (if there's equipment between lines), 4' then cess. Theoretically there is a 10' between pairs of fast and slow lines on four track and between running tracks and any side tracks... but this is honoured by omission more often than not because lines were built before the 10' rule came in. the exception is the original GWR mainlines which (having been Broad gauge) have ample width.

    The one most people know is loco depot track... but you know about that!

    What do you do with cleaned out ballast waste or the old ballast that you've replaced? [I may be repeating that].
    It can go up or down the embankment beyond the cess... be used for car parks or other hard standings... it is rarely just dumped except along banks.

    I might think of something..

    Oh yes... rail length!

    Don't make life hard for yourself by trying to model it...except for car loads and rail laid ready for use or removal...or stack for either. also get ties stacked or spaced out along the track side ready to go in or to be collected

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