Ballast/earth height in yards question..

MarkInLA Sep 18, 2013

  1. MarkInLA

    MarkInLA Permanently dispatched

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    Is the reason in here (yard, engine stall/roundhouse areas) that tracks are right even with the soil/earth around it due to track (ties) originally laid right on ground ? Or, is mostly all track laid on 2-3 foot deep ballast but the soil is built up around it to make it easier for switch crews to get to ground throws/couplers and walk cross many tracks ? Is it simply erosion out in countryside were tracks are in weeds, yet it's on (now hidden) deep roadbed ? Or, is it, again, simply laid on little or no ballast to begin with when it's a say, 50 lb.-rail spur out in the woods ? Those 1860s photos of track do look right on the ground allot, at ends of lines especially....Did it just continue this way but replacing ties and changed to heavier rail over the decades ?
     
  2. jpwisc

    jpwisc TrainBoard Member

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    What era in particular are you asking about? In the 1860, ties were ofter laid right on the ground for speed of getting a line in. Improvements could always be made later.

    Today a good amount of engineering goes into any trackage. Base will depend on soil in an area, sand drains well and would not need the same sub-roadbed that a clay soil would need.
     
  3. JB Stoker

    JB Stoker TrainBoard Member

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    When possible, railyards were intentionally made lower than the surrounding main lines. This prevented cars or consists from rolling away, as they were trapped in a dish.This also allows for doing marshalling by giving cars a shove (kick) and letting them coast, rather than having to escort each car all the way to each consist being formed with the switching engine. In an ideal dish you can give cars a kick and let them coast into the consist without fear that the momentum would launch the entire consist out onto the mainline. I am not 100% sure that modern safety practices allow for doing this anymore though. Not building up a roadbed is also cheaper too, which railroads were always looking for.
     
  4. MarkInLA

    MarkInLA Permanently dispatched

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    Yes, I'm very aware of what they call 'the bowl' for yards and that sidings ( 'going in the hole' ) also descend from main to ensure cars don't drift into switch if brake is off..But, answers to my question are still hazy..Let's skip 1900s era ( I did always believe ties where on the ground then )...I mean ( aside from the 'bowl' shape ) are the yard and spurs which look as if they are on the ground, in fact on the ground at installation time ? Or, are they on ballast but soil filled in between on purpose and/or from erosion ? I don't expect it to be high ballast like on the main..But is there a layer of ballast present underneath yards/spurs but just not visible to us ? I.E. Modern yards from say, 1930s, 1940s on...
     
  5. JB Stoker

    JB Stoker TrainBoard Member

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    I think you are confusing roadbed and ballast, Mark. Roadbed has to be compacted material , either natural or added, capable of withstanding applied load and hopefully resist erosion-etc. Ballast is relatively loose filler intended to fill the space between ties yet provide complete drainage and extend tie and rail life.
     
  6. maxairedale

    maxairedale TrainBoard Member

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    I think that Mark is wondering, why the surface of the ground, be it dirt or stones (mostly dirt) is frequently at or near the top of the rails in yards. At the top on the outside of the rails and between the rails.

    If that is not correct Mark please feel free to correct me.

    Gary
     
  7. rch

    rch TrainBoard Member

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    No, tracks in yards and service areas are not constructed directly on the ground. The earthen base must be compacted material graded to allow for drainage then ballast is placed and finally track is laid upon it. If you get a chance to see a new yard it's pretty obvious. There are some new facilities being constructed now in oil-rich areas of the western US, so if you are near those areas it might be a good bit of fun to check one out. If you do a search for engineering specifications for railroads, you might find something useful.

    Yes, it looks like these areas are constructed directly on the ground, but the "ground" comes after the tracks, so to speak. What happens over time with these areas is they are not maintained in the same way as main and siding tracks. Typically, a main track undergoes an undercutting and ballast cleaning maintenance cycle. The ballast is like a sponge or a filter that fills up with particulates so it must be cleaned regularly or it no longer works to drain stormwater. In yards and service areas, trains move at much slower speeds and exert lesser forces on the tracks, so the tolerances for rail size, tie age, ballast cleaning and so on are much more forgiving. Maintenance does occur in yards and in service areas, but the maintenance cycle is much longer. Therefore, it is common to see yard ballast filled with all sorts of spilled lading, including coal, coke, sand, cement, grain and to a lesser extent in the modern era, liquids such as various oils, molasses, corn syrup, tallow and so on. All this spillage, along with mud splashed up from the rain-soaked earthen base and the sinking effect that occurs when a yard is experiencing precipitation, causes the "ground" to collect on top of the ballast and fill in the once well-defined sloped shoulders of the ballast.

    As far as the elevation of the main and sidings compared to the yard is concerned, I believe it is a result of the need to prepare a larger footprint for the higher speed tracks than an attempt to keep cars from rolling out of the yard. The higher the ballast is piled, the wider the ballast is at the base of the shoulders, which allows the load of the train to be spread over a larger area. Main tracks are protected from unintended movement from auxiliary tracks by derails, not gravity. Gravity is often used (or worked against) in the course of operating a yard. Cars may be kicked on a gentle grade (up or downhill) or pinned on a steeper grade and allowed to come to rest against other cars (bumping posts) which are secured against movement by handbrakes, skates or electro-pneumatic retarders that grip the wheels. However, gravity is not relied upon to prevent cars from entering the main track. Again, that is the job of a derail.

    If you consider the massive task it is to grade an area a couple hundred feet wide and often a mile or more long to a bowl, especially considering the equipment and manpower required for those 50 year old and older yards, it's easy to see why many older yards were constructed with a minimum of grading. Many yards are situated on the side of a gently sloping hill (others, not so gentle). Some have provisions for drainage within them, such as underground pipes or open channels. Others rely on sheet flow drainage across the yard and still others use all the above methods of drainage.

    I work at a few different yards of different eras and the approach taken by the design team of each couldn't be more different. The oldest yard is on a 1% to 1.2% grade, which is ridiculous in a yard. Any car that begins rolling in that yard had better have several secured cars to couple into or it will roll out. In fact, there is a minimum of five handbrakes required before cars can be pinned in that yard. The newest yard is like an inverted bowl, with a ridge running down the middle. It is a very gentle grade, however, so cars can be kicked at this yard and they will travel hundreds of feet. It is flat enough that cars will rarely roll back, but high winds regularly wreak havoc. Hump yards are a different animal, but the bowl tracks at the yards I'm familiar with are actually pretty flat. The hump itself and the switches leading to the bowl tracks are on a steep grade, but it's pretty flat when you get in there.

    Service areas tend to accumulate lots of sand, oil and spilled fuel. Older facilities look like the rails are laid directly on the earth, even under it almost, since the soil-like combination of oil, fuel and sand covers much of the ground. This gritty gunk is almost like a soft asphalt that never hardens and it gets compacted by the high volume of foot traffic around it. Modern facilities are constructed with spill pans to minimize environmental impact from a spill and they are cleaned regularly. Often there will be a large holding tank for the runoff from the service area, since it is likely to be contaminated and cannot be freely released into streams, rivers and lakes.
     
  8. MarkInLA

    MarkInLA Permanently dispatched

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    rch (above), like....wow !! Very informative. I'm flattered as to the depth of your reply...So that's what those square pan looking things are on this spur I walk on sometimes. Didn't savvy your " minimum of five brakes required ".. 1 brake per car, no ?... I do see what you mean about siding lower than main is merely a lack or none need of high shouldered ballast, not for runaway car protection..
    Gary, correct, that is what I meant. Except, not to top of rails but almost always to top of ties; ballast present with no shoulders though..
    Thanks, Mark
     
  9. rch

    rch TrainBoard Member

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    I worked in the civil engineering field for 20 years before beginning my railroad career, so I suppose I have a unique perspective.

    Minimum five brakes means that cuts of cars or trains cannot be left unattended in that yard without a minimum of five cars secured. Cars may not be cut off in motion into tracks that don't already have at least five cars secured in the track to act as bumping posts. The handbrakes must be tied and you cannot rely on the force of the airbrakes applied in emergency. Some cars have a handbrake that only secures one truck on the car (many carbon black cars work this way) and other cars are made up of multiple platforms but have fewer handbrakes than platforms (such as five platform intermodal cars with a handbrake at each end of the car), so you even have to be considerate of that when determining the number of cars you need to secure in the track as bumping posts. Not only that, if all the cars secured are empties and you will be cutting off loads into the empties, it will likely require more handbrakes to prevent undesired movement.
     

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