General layout shape - more curved or more straight sections?

TrainzLuvr Nov 14, 2017

  1. ppuinn

    ppuinn Staff Member

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    The scenery in Vikas' yard looks great! You could certainly do something similar with yours.

    Is there enough space to put a yard lead 18.25 inch radius parallel to the 20 inch radius main around the east end of the support column shelf?
    How much space is there from the fascia of the outside shelves to the north wall? (Assuming the door is at least 32 inches wide, there could be a minimum of somewhere close to 36 inches.) Would someone setting out a train on an arrival track be able to pass an operator sitting on a wheeled dentist's stool or chair, in order to stay with his train and uncouple his loco(s), and turn his loco or park it in an engine facility without interfering with the seated operator sorting cars from the east end lead into the classification tracks of the yard?

    How many cars do you plan to have in your trains (affects siding lengths along main, how many cars are available to be switched into/out of industries in a particular train, length of yards, length of yard leads; also number of locos needed to pull cars up a helix of x percent grade).
    If you have a 2 percent grade and use 2 locos, you probably will be able to consistently run 12 to 15 car trains and up to 20 cars with 3 locos.

    What are your thoughts about number and types of trains to be run in an operation session? I suspect two trains at a time on the main will be the maximum until operators are more experienced. And, if most jobs are designed to take between 15 to 30 minutes, you might be able to run 4 or 5 mainline trains in an hour. A third operator could work the yards outside the support column shelf on both the upper and the lower level (one train out of each and one train into each 15-30 minutes later). How do these speculations of mine match your expectations?

    I think that, if you have 4 classification yard tracks, 1 arrival track and 1 departure track, and 1 running track (or a main?) separate from a yard lead, plus aisle space for an operator with an arriving/departing train to pass while a seated operator is working the yard, it would be possible to put most of the lower and upper level yards on the outside of the support column shelves (as in your post above) with engine facilities and other yard elements on the inside. Or you could leave the backdrop out on the west end of the lower level, run the yard lead "through" the partition and along the west wall, and have all the turnouts to the classification and arr-dep tracks within sight and reach on the outside of the support column shelf at the west end of the yard. The turntable and engine facility would be at the east end of the yard (but NOT at the end of classification tracks, as Vikas' was), and trains would still come onto the arrival track in the yard from around the east end of the support column shelf.
     
  2. nd-rails

    nd-rails TrainBoard Supporter

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    Err, don't understand- regardless of proto-fiction- when would an entire yard ever terminate at a turntable? It can only ever turn a locomotive, period.
    dave
     
  3. ppuinn

    ppuinn Staff Member

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    Dave (nd-rails),
    [Vikas' track plan is posted HERE in his blog.]
    You are right...We'd probably never see a prototype yard with tracks terminating at a turntable, but Vikas' yard configuration isn't the first time I've seen this type of track plan on a model RR. Several years ago, when searching online for switching layout track plans, I came across a plan in which someone proposed a similar arrangement in order to fit more operations in a 3-track yard on their very small N-scale switching layout. (...although they referred to it as a shunting layout, which led me to think the modeler was from Europe [UK? India? Australia?]).

    TrainzLuvr,
    Despite your somewhat narrow support column shelves and aisle by the door, I still think there is plenty of room to fit in a more prototypical track arrangement.
    I think the scenery around Vikas' (very unconventional) yard is wonderfully done; however, I would encourage you to plant any fine-foliage trees--like those on the left in the 2nd picture of Vikas' yard--between the turnouts and the backdrop, instead of between the fascia and the turnouts. This is because these lovely trees are very delicate, so they are extremely vulnerable to damage during track cleaning or repairs. If your turnouts use ground throws instead of motors, the fine-foliage trees may be easily damaged by hands, shirt sleeves, or elbows when operators reach for a ground throw. Also, during operations, any trees (fine-foliage or other) in front of turnouts may block the view of switchpoints and cause operators to run through an incorrectly aligned turnout.
     
  4. TrainzLuvr

    TrainzLuvr TrainBoard Member

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    @ppuinn

    I'm still trying to sort out heads from tails from everything you wrote. To be honest, some of that stuff is presently over my head, that I don't even know where to start figuring it out. I thought the benchwork part was difficult but that was just engineering and labour.

    I haven't done anything for the past several days and I feel a bit demoralized at the moment, as well as overwhelmed with the (daunting) task ahead. Any guidance you can offer would be appreciated.

    Regarding the Vikas-look-alike yard and my copy of it, I think we are not on the same page. I envision it being a Staging not Classification yard. It is train storage for trains that exist outside my railroad, and could be potentially a hostling job during an op session. But it is definitely not meant to be a classification yard needed to be worked on, trains cut and sorted, etc. That's why the turntable at the end, to make it easy to turn the locomotive around and ready the train for another potential run during an op session.

    In reality, it's kinda of a bummer that I'm doing that there because I already bought enough Atlas Code 80 track (150 ft.) and remote turnouts (40) in December to build two double-ended auto-restaging (hidden) areas on the peninsula, based on my original plan.

    So now the plan has changed, and I'm making a visible Staging using that same Atlas Code 80 track which isn't the nicest looking one, nor am I utilizing all of it either as I'd be left with half the track and turnouts since it's not double-ended nor exactly the same configuration. You said there's plenty of room for more prototypical track arrangement, please share how you envision it (ideally in visual form rather than words).

    I've been dabbling with some LDEs on the lower level, and here's what I have so far - perhaps you could use this drawing as a reference for any visual representations, or what not. Thanks!

    [​IMG]
     
  5. TrainzLuvr

    TrainzLuvr TrainBoard Member

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    More progress this weekend, fitting the subroadbed on the lower level!!!

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    Ran out of time so the peninsula blob is unfinished, last remaining item. And it appears I'm short couple of feet of plywood, bleh. I'll have to stitch some scraps together to fill in the holes.
     
  6. ppuinn

    ppuinn Staff Member

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    Shelving is looking good!
    A comment on the helix shelving (which it looks like you may be working on soon).
    If you are going to enter the helix at 31 inches elevation, be sure to make the shelving on the aisle side of the oval or triangular helix or at the base of the oval by the gap as thin as possible (so the lower edge of any supports under the plywood on the aisle side of the oval or triangular helix or base of the oval or triangular helix by the gap are as far from the floor as possible).

    On a previous layout, I had a 36 inch elevation lower deck consisting of 1/2 inch Homasote and 1/2 inch OSB panel supported on nominal 1x2 inch (about 1.6 inches) stringers, resting on nominal 2x3 inch L-girders (about 2.25 inches) making the lower deck about (.5 +.5+1.6+2.25) 4.85 inches thick...meaning I had to crawl on hands and knees under the lower edge of the L-girder at 31.15 inches from the floor to enter the helix on that layout. On your layout, if those metal braces are 2 inches wide and the plywood is 1 inch, you will only have 28 inches clearance to get into the helix. Fortunately, if you enter the helix from the base of the oval by the gap or the corner of a triangular helix by the gap instead of the side of the oval between the peninsula and the south wall shelf, you will have the inside length of the oval to straighten up in, instead of just the width. (The helix on my earlier layout was a circle [and of smaller diameter, too, than the width of your oval] which made entering the helix on hands and knees a painful exercise in contortions.)

    I suspect that, if you use the 1 inch plywood for a 1.25 inch wide helix ramp in a bowl-shaped helix, it will be strong enough to span a 24 to 27 inch space wherever you enter the helix, especially if you run a strap down from the inside edge of the next higher loop to the outside edge of the lowest loop.
     
  7. TrainzLuvr

    TrainzLuvr TrainBoard Member

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    @ppuinn

    I finished the missing benchwork, so the helix area is now what's left to do. I kinda regret using 3/4" plywood though, it is an overkill.

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    The amazing part is that everything is perfectly levelled, and I don't mean in the 2D plane of individual benchwork pieces, but across the aisles themselves. :D

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    Speaking of a helix, past week I have been dabbling with an idea of accelerating the build by using pre-made pieces, such as KATO or Tomix. I ruled out KATO because the curves are superelevated and it also appears that Tomix has a nicer selection with their double concrete slab track.

    Here are some of the helix designs I'm contemplating, what do you think?

    [​IMG]

    The reason for going this route is multi-fold.

    At first I thought that it would be expensive to go this way (and it might be), but considering that I never compute my time into any project, I realized that the time is the most valuable commodity to me. I would have to cut all pieces out of wood (or have them laser cut, if I used 3/8" baltic birch) and I mean there could be a lot of fiddling to fit everything together. Then lay track down (let's not forget cork/foam roadbed), glue and clamp, solder track and feeders, rinse and repeat for each loop. Fit all loops together onto threaded rods, adjust, etc...

    I don't see myself building a bowl-shape helix because it would require a lot of effort and more space than I really want my helix to occupy.

    The construction with Tomix pieces will be super simple because I don't need to mess with roadbed, subroadbed, laying track etc. Only need to build the risers which will be a standard way of doing a stacked helix (threaded rods and plastic tubing spacers in-between levels).

    Also, Tomix track comes with a nice (removable) barrier on both sides so I don't have to worry about building that either.

    This is a 465/428.45mm (18.3"/16.9") radius track, 45 deg piece:

    [​IMG]

    And this is a 539/502mm (21.2"/19.76") radius track, 22.5 deg piece:

    [​IMG]

    Bottom line is really that, bottom line. I have to figure out the actual costs of doing all this and what I could afford to do (or willing to spend on).

    I don't really think helix is where my battles should be won, so that part should be fast/easy and bulletproof. The battles should probably focus on the track plan and reliable/enjoyable running.

    Of course, I'm still an armchair model railroader (I don't have a layout yet), so I could be totally wrong about this. ;)
     
  8. TrainzLuvr

    TrainzLuvr TrainBoard Member

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    I forgot to add, there's another option on the table and that is a vertical elevator.

    Although, I do not have a long enough section of the wall on the East to have an elevator to fit 7' long trains, it would have to curve around the South-East corner which only complicates a complicated design necessary to match rail heights perfectly. But I still think it's doable...
     
  9. ppuinn

    ppuinn Staff Member

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    Space limitations are a valid reason to go with a stacked helix instead of a bowl-shaped helix.

    What factors are driving your decision to go with a double track helix, instead of a single track helix?
     
  10. TrainzLuvr

    TrainzLuvr TrainBoard Member

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    3 decks on my layout; double (or triple) main line; being able to have trains run in both directions (up and down) simultaneously; future-proofing...
     
  11. ppuinn

    ppuinn Staff Member

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    If you have a double track helix and you plan to use right-side running, design the helix to rise in a counter-clockwise manner. This means the larger radius is on the outside as you climb, so the outside track will have a slightly lower grade than the tighter radius inside track. Additionally, there will be slightly less wheel friction pulling cars around the outside curve than around the inside curve. Combining the difference in grade with the reduced friction around the curves will yield a 1 to 3 car difference in total number of cars per loco that can be pulled up the helix on the outside track versus on the inside track. (Yes, pulling power of specific engines, percentage of grade, and length of straight track in an oval or triangular helix will also influence that "1 to 3 car difference", but regardless of loco pulling power, grade, or ratio of straight to curve in a single helix loop, climbing on the outside track will always be proportionately easier than climbing on the inside track.) If you plan to use left-side running, then the helix should be designed to rise in a clockwise manner.

    When calculating the cost of a helix made with sectional track, be sure to include cost of turnouts, cross-overs, and/or crossings to get from the inside descending loop to the outside loop to access the middle level deck. Without middle level access for both ascending and descending tracks, operations will be severely limited, and a very large percentage of every train's mainline run must be hidden in the helix.
     
  12. TrainzLuvr

    TrainzLuvr TrainBoard Member

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    Isn't the larger radius always on the outside track regardless? :)

    Perhaps in my case it might be more convenient to go clock-wise so that the outer track climbs up and ends up closer to the South wall on the middle/upper levels.

    Albeit the lower level track would have to turn down out of the yard on the left side, to start the ascend, but that's fine as it would clear the inner track and let it merge into the yard from the top (closer to the South wall).

    As I'm most likely making an oval, it should be easier to add cross-overs, even if they are on the grade. Has anyone ever done crossings over two tracks (is that even practical)?

    Where do I find information about individual locomotive pulling power (4-axle vs 6-axle, how many cars vs grades, etc) ?
     
  13. ppuinn

    ppuinn Staff Member

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    I can't offer info about specific locos' pulling power, but in his "Make it Run Like a Dream: Trackwork" (Model Railroad Hobbyist magazine; mrhmag.com), Joe Fugate has a chapter on how curves, grades, and free-rolling trucks (vs "typical" trucks) affect the number of (HO) cars that can be pulled by a loco.

    (Referencing John Armstrong's information in "Track Planning for Realistic Operation" about cars with free-rolling trucks which roll on a .5% grade, and cars with "typical" cars which roll on a 2% grade), Fugate offers a table that shows a loco can only pull about half as many free-rolling cars on a .5% grade as on level track, about only a third as many on 1%, just over 1/4 as many on 1.5% and about 1/5 on a 2% grade. For "typical" trucks, the percentages don't fall off as fast, but that is because the locos pulling cars with typical trucks could not pull as many cars on level track. Locos could pull 80% of their original number of cars with typical trucks on a .5% grade, 62% on a 1% grade, about half as many on a 1.5% grade, and 43% on a 2% grade.

    Number of cars that can be pulled by a loco is also influenced by how many cars are being pulled around a curve (instead of along straight track). Fugate provides a table (originally compiled by John Allen on his Gorre & Daphetid and presented in Don Mitchell's book, "Walkaround Model Railroad Track Plans") showing the relationship between curve radius and the amount of drag/friction on (HO) cars, and equates curve drag to grade: tighter radius increases curve drag, which reduces loco pulling power as if it was pulling cars up a steeper grade. On an HO layout, a 16 inch radius curve on a level section of track supposedly led to reduced loco pulling power as if the loco was pulling the string of cars up a 2% grade, 18 inch radius = 1.8% grade, 20 inch radius = 1.6%, 22 inch radius = 1.5, 24/1.3, 26/1.2, 28/1.1, 30/1.1, 32/1.0.

    An oval helix will have fewer cars on curved track than a circular helix, and the oval helix with a larger straight to curve ratio in a single loop will have fewer cars on curved track than a helix with a smaller straight:curve ratio. For planning a helix, this means, with comparable radius curves, the shape that gives the most straight track in a single loop will have the least amount of curve drag. Additionally, for two helixes with comparable radius curves but different amounts of straight track, the helix with more straight track will also yield a longer run in a single loop than the helix with less straight track, so the rise per loop will be greater, even if the grades in each helix are the same (or the grade could be reduced so the amount of rise per longer run is less).
     
    Last edited: Mar 30, 2018
  14. ppuinn

    ppuinn Staff Member

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    Are you planning to use right-side running? If so, then a double-tracked helix rising clock-wise will have both a steeper grade and greater curve drag on the rising inner track than on the descending outer track. Additionally, descending track exiting at the back of the middle and upper level south wall shelves will be lower than track at the front of the shelves...not unworkable, but harder to maintain and operate (you'll be more likely to bump trains, trees, structures at the front of the shelf when reaching toward the back part of the shelf), and taking scale railfan height pictures of the back half of your shelves near the helix will be MUCH more difficult (because the lowest you'll be able to get your camera lens will still make pictures look like they are taken from a helicoptor).
    If your helix climbs with a counter-clockwise turn (and if you are using right-side running), then the rising track is on the outside--lower grade and less curve drag--and the tracks near the front of all 3 shelves can be lower than the tracks at the back of each shelf...IMO, a more pleasing appearance (but others' opinions may differ).
    Another advantage to the counter-clockwise rise: if you start your rise from 31 inches about 2 or 3 feet before entering the bottom of the helix, you will be able to put all of the turnouts to the arrival/departure and classification tracks along a yard lead that starts at the turnout to the main (aka departure track), crosses the arrival track at about 30 to 45 degrees, extends through the yard ladder made of right hand turnouts serving the arrival track and the 4 to 6 classification tracks, and then bends around the base of the oval onto the shelf (31 inches elevation) by the gap north of the helix, where there could be a few short industrial spurs for spotting cars.
     

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