Super-Elevating Curves

BCR 570 Mar 2, 2009

  1. BCR 570

    BCR 570 TrainBoard Member

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    I have spent some time learning how to super-elevate curves on my little test bed using a method described in a recent issue of MR.

    I began by laying out strips of masking tape:

    [​IMG]


    Then I stacked them, cut them into strips and formed them into a curve:

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    Here is a strip in place on the roadbed. Advantages of this method are that the strips form easily to the curve, and they are self-adhesive!

    [​IMG]


    Another advantage is that they will be impervious to the glue and water used during ballasting. Here is a piece of Code 40 flex track in place on the roadbed with the strip under the outside rail:

    [​IMG]
     
  2. BCR 570

    BCR 570 TrainBoard Member

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    So what does that give us? The engine on the left is sitting on the super-elevated curve. As a comparison, the engine on the right is sitting on level benchwork:

    [​IMG]


    Why go to all this trouble? In addition to superior train performance, so I can take photos like this:

    [​IMG]


    And like this:

    [​IMG]


    Thanks for looking,
    Tim
     
  3. porkypine52

    porkypine52 TrainBoard Member

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    Looks good!
    That was one main thing that really impressed me when I got the chance to visit Allen McClelland's Virginian & Ohio Railroad. Every mainline curve was super-elevated and it really enhanced the layouts looks.
     
  4. pastoolio

    pastoolio TrainBoard Member

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    Tim, Looks great! I love super elevated cruves. Seems like a lot of steps to cut out the tape though. I just use cardboard strips under my roadbed and glue them down as I glue down the roadbed. I do agree, taking pictures of a loco leaning into the curve sure looks super! :)

    -Mike
     
  5. LOU D

    LOU D TrainBoard Member

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    Tim: Two words..Be CAREFUL!! I've been superellevating the curves on my RR's for a long time,you CAN go to far!! I do it by sanding my cork roadbed at an angle in the curves,easments and all,and most nowhere NEAR the amount in the pic you posted.Many locos will definately have both pickup AND traction problems way before you get to what you have there.Most locos will at least occasionally act erratically,stuff like old Atlas Kato RS11/RS3 units,and Trainman GP15's won't work AT ALL,especially in the entrance to the curves....The most I've been able to totally reliably do is just enough to be visible..
     
  6. Scott Teague

    Scott Teague TrainBoard Member

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    I had trouble with some of my SD80,90 MACs on going into curves like you are talking about. You got to be careful.

    Scott
     
  7. gregamer

    gregamer TrainBoard Supporter

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    That looks cool Tim. I super elevated curves with masking tape on my last layout. I layered the tape right on the subroadbed, then stacked the roadbed on top. I think I like this method better, it gives you more control.
     
  8. Arctic Train

    Arctic Train TrainBoard Member

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  9. RGW

    RGW TrainBoard Member

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    Superelevation made easy

    Brian, many thanks for citing my article. I hope you found it useful, we continue to superelevate nearly every mainline curve on the RGW using that method with great success.

    Tim, I disagree that your method will be "impervious" to water/glue during ballasting. It is directly exposed to wet water and if the seal at the outer edge is not solid, it does run the risk of separation from exposure to the water, so I urge caution. By placing the tape under the roadbed, this problem was completely eliminated.

    Also, in my pursuit of quality masking tape I found this 1/4" wide, 5.5ml thick brand from Uline. It is perfect for superelevation and requires no cutting. You'll find it here:

    http://www.uline.com/Product/ProductDetail.aspx?model=S-3049&ref=3108

    Hope this helps. Michael
     
  10. sandro schaer

    sandro schaer TrainBoard Member

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    neat idea !
    i simply use thin strips of styrene. since i use contact glue to hold the track on the woodlands trackbed these pieces of styrene hold in place with no problems.
    all my curves are superelevated. even if i have no curves with less than 20" radius.



    btw, your bc rail units just look great. they really catch the look of the real ones.
     
  11. BCR 570

    BCR 570 TrainBoard Member

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    Thank you all for your replies and input. It sounds like I will need to conduct an operating trial on a longer curve to verify that I will not have operating problems.

    Tim
     
  12. NSES40DC2775

    NSES40DC2775 TrainBoard Member

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    I was thinking that you could start the super elevation on the strait before the train enters that track.
     
  13. DaveWonders

    DaveWonders TrainBoard Member

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    AFAIK that is not prototypical. As the track is eased into the curve, the elevation is eased as well. So, assuming that the radius is sharpest in the middle of the curve, it would also be the most tilted. But any track that is straight should be flat and even.
     
  14. LOU D

    LOU D TrainBoard Member

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    Dave,there has to be at least a slight transition on the straight track before the curve.Just look at a stockcar track.If the superellevation starts on the curve,the superellevation would only be an abrupt lump on a sharp curve..
    Tim,I think the problems are more pronounced on tight curves.The trucks lose contact because they're kinda contorted to the track profile.On big sweepers,you may be able to use fairly high banking,but on tighter turns,it becomes a problem.My turn radius averages 14 inches or greater,but my trains just seemed to act funny on it.I'm just lucky I found out before I did the whole mainline...
     
  15. jrwirt

    jrwirt TrainBoard Member

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    I get the close-up appearance benefits, but I doubt there is any benefit to train performance. I suspect a long N scale train actually becomes more prone to string-lining as you move the car center of mass toward the inside rail.
     
  16. DaveWonders

    DaveWonders TrainBoard Member

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    I'm not sure about that...I still think that just as a curve has an easement to go from straight to the tightest radius in the center of the curve, the super elevation would begin at the easement and increase from flat to the most angled in the center. Depending on how subtle the easement is it could very well look like the track is straight although it is gently curving. I can't see why you'd want a straight track not to be level.

    Now, in modeling, if your track has no easements it might look better to start the S.E. on straight track...that I'm not sure of and I guess it would be subjective. As mentioned we model S.E. for looks - not functionality, so it would be whatever looks better to the modeler.

    I get the banks on a racetrack metaphor...however I don't think you can compare the center of gravities of a race car and a train. You could bank a straight away 45 degrees and as long as the race car is going a good speed it's going to go straight and definitely not tip over...but a train on a straight track that is banked is just begging to tip.

    BUT, I'm no physicist and no track layer so...Just explaining how I think (and stress think) it makes sense.
     
  17. Mad Yank

    Mad Yank TrainBoard Member

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    Reality and Modeling

    And THERE is the POTENTIAL problem; superelevation MUST be done VERY carefully, or that beautifullly-detailed loco WILL kiss the carpet-covered-concrete in the Train Room, sooner or later!
    Only the 3-5-year-old-contingent runs the trains fast enough to warrant superelevated track on our layouts (well, okay; I do it when testing an engine or a track section, but that's ONCE - and never again), so we're NOT going to get physics on our side in keeping the wheels on the rails in a SE curve. Which means we MUST cheat on how we do it. Where the 1:1 guys might have the outside rail as much as 12" higher than the inside one, we really don't DARE go more than a scale 2-3" - if that! Especially since the CG on OUR locos is usually HIGHER than on the prototype 1:1 units.
    On my Scenic Ridge styrofoam practice layout, the closest I'VE come to an SE curve is where the two tracks come down from the mountain on the "east side" (well, one coming down, one going up), as viewed from looking at the layout from the long side with the siding next to the streambed. Anyway, Woodland Scenics calls it the 'front', so I call it the front as well. I just smoothed those two curves with Foam Paste and sanded them slightly SE to provide a banked turn (just barely) and glued down the Unitrack.
    I get the SE visual effect without risking anything falling over; I can drop stuff on the floor without any help, thank-you-very-much!
     
  18. Powersteamguy1790

    Powersteamguy1790 Permanently dispatched

    I've super elevated the curves on the JJJ&E nine years ago and have had no problems after doing it. It certainly helps steam locomotives entering curved radii.

    The pilot truck of steam locomotives has a tendency to lift off and derail when entering curved radii. Sper-elevation or "banking" the rails works.

    As a side note, all entrances and exits to most highways are super elevated or "banked".If this didn't occur, there would major accidents on these roads every day.
     
  19. LOU D

    LOU D TrainBoard Member

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    Dave,the superellevation has to start at least in part on the straight.The easment,after all,IS part of the curve,so the superellevation has to already be there when the easment starts.The abrupt change from flat/straight to curved/superellevated needs to be gradual.It also needs to be consistant.The angle doesn't keep increasing to the center of the curve,then drop off,it needs to be consistant.If you have 2 degrees in the center of the curve and the entire curve is a 20" radius,then it should be 2 degrees through the entire corner.
     
  20. RGW

    RGW TrainBoard Member

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    Gents, a quick refresher on SE. First and foremost, modelers cannot prototypically create SE because in the prototype, they lower the inside rail. So unless you have figured out how to work SE into the subroadbed, your only option is to add height to the outer rail. Second, the maximum SE in the prototype is 6 inches. This is about 1/16" for HO and 1/32" for N. Third, and most germane to the discussion in the last few posts, the transition to full SE (6”) begins in the easement and ends when the curve begins. It maintains the 6” SE through the curve and then descends back to zero through the exit easement. For a more complete discussion, I urge you to read John Armstrong’s book, “The Railroad, What It Is, What It Does”.

    Michael
     

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