super elevated track on curves

Discussion in 'HO Scale Model Trains' started by eric halpin, Nov 11, 2006.

  1. eric halpin

    eric halpin Eric Halpin

    I would appreciate comments regarding the value of super elavating outside rails on curves. I understand that it can enhance appearence somewhat but have also heard that it can interfer with running of the train especially through turnouts and the like. Is it worth doing?? Thanks
  2. fsm1000

    fsm1000 Member

    One, on models it is 90% a looks thing.
    Two, you don't super elevate switches [turnouts] because elevation is for high speed and you don't go fast over switches [turnouts].
    Three, it really does improve appearances if used.
    Four, problems will not arise if you only use it where the real ones would use it. I.E. on curves AND you put in some easement on the approach part of the curve.
    If you have a small layout [4 x 8 plywood type of thing] then elevation might be out because of space restrictions.
    Otherwise go for it. If you have a nice winding 10 long piece of track then elevate it. Or a long graceful curve you will travel at over 70 miles per hour then go for it.

    I hope that helped. :)
  3. Santa Fe Jack

    Santa Fe Jack Member

    I'm glad you brought that up, Eric. I could use that on some of my curves, and where they are elevated on graded risers it would be easy to do -- just sand the foam down a bit.

    Actually, I suppose that it could possibly degrade the performance of the train/track, unless the train is going a speed that is appropriate to the amount of superevelation. Too slow, and you would tend to pull the train off the track rather than around the curve. I wonder ...
  4. fsm1000

    fsm1000 Member

    Nope, the elevation is not so high that a slow train would fall over etc. But it is high enough to help let the train go faster.
    This is not a car speedway LOL :D
    Anyhow, another way to elevate is to simply put a 1/16th or a 1/8th inch thick piece of wood [matchsticks with the head cut off or toothpicks are often use as are RR ties] on the outside of the ties will elevate it enough. The ballast hides the wood later.

    Hope that helps.
  5. LongIslandTom

    LongIslandTom Member

    My observation is that some superelevation can actually give me smoother running..

    I don't have much room for a pike, so I was forced to use sharp 18" curves. I started out wanting to run big 6-axle locomotives like SD40-2s on my pike, but they had a devil of a time going around the 18" sectional snap track I got.

    What I found was that the leading wheel on the 6-axle trucks on my SD40-2s would derail on the 18"-radius curve-- It would ride up and over the railhead on the outside rail of the curve. The presence of the rail joints due to the sectional track just presents additional kink points where the lead wheel flange can catch and ride over the rail head and derail.

    I was able to minimize that problem by switching to flex track (gives me longer stretches between rail joints), and superelevating the curve to make it a bit harder for the flanges on the lead wheel ride up and over the railhead. I shimmed the outside of the curves using pieces cut from .030" sheet styrene. The .030" superelevation is quite subtle-- You can hardly tell the train is leaning into the curve, but boy what a difference in reliability it made for my 6-axlers.

    I hardly use my 6-axlers these days though.. 4-axle Geeps and GE dash-whatever-Bs just look a lot nicer on a small pike. :D
  6. Russ Bellinis

    Russ Bellinis Active Member

    How much superelevation does the prototype use? 1/16 inch would be about 5-6 inches in ho scale, 1/8 inch would be close to a foot in ho scale. I think if we knew how much the prototype superelevates track, then using styrene in thicknesses measured in thousanths of an inch like Tom mentioned would allow us to get closer to scale. If our superelevation was close to the scale the prototype runs it might work as well as the prototype.
  7. fsm1000

    fsm1000 Member

    Russ sorry about that, I was indicating O scale. That would be 3 to 6 inches, like the prototype.
    The higher the speed the steeper the elevation. If you are going 100 mph or more then use 6 to 9 inches, other wise 3 to 6 inches is fine.
    Hope that helps.
  8. doctorwayne

    doctorwayne Active Member

    If you're using open grid or L-girder benchwork, in conjunction with plywood sub-roadbed on risers, it's fairly easy to introduce superelevation, along with natural easements into it.
    With the risers attached to the sub-roadbed, but not to the benchwork, raise the sub-roadbed to the desired elevation, then fasten the risers which are just outside of either end of the curve to the benchwork. These should be perfectly perpendicular to the benchwork, and the roadbed throughout the total length of the curve should be temporarily supported by these two points. Now, locate the riser which is closest to the half-way point through the curve, and carefully raise it until the centre-point of the curve is level with the two endpoints. If your curve is on a grade (which most of mine are), then the riser and roadbed should be raised only far enough to keep the grade fairly constant. You can use lines and levels to determine this, but it generally works just as well to just "sight" it. When you have it at the proper height, make a reference mark on both the riser and the benchwork at the point where they will be fastened together. Now, grasping the bottom end of the riser, pull it to the outside of the curve. One of two things will happen: either the roadbed on the inside of the curve will drop, or the roadbed on the outside of the curve will rise. It's preferrable to have the outside rail higher, so adjust the vertical position of the riser so that the reference mark that you made earlier lines up on the inside of the curve. Adjust the amount of superelevation by eye, then, using screws, fasten this riser to the benchwork. Now, roll a train through the curve. The individual cars should gradually heel over as they enter the curve, and gradually return to vertical as they exit. If it looks good at the speed that you'd normally be running the train, then you're almost done. Otherwise, adjust that middle riser until you are satisfied. Then, with the test train safely out of the way, work your way around the curve, fastening the remainder of the risers to the benchwork. Do not attempt to move them either to the inside or outside of the curve, or you'll upset the natural easements on either side of the centrepoint, simply fasten them in place where they fall.
    Here are a few examples, although the effect is most noticeable on a moving train.
    The effect is pretty subtle here, as this curve (on a grade) is posted at 35 mph for freights and 45 mph for passenger trains.

    This one is a little more obvious, even though the speed limit through the grade here is 35 mph.

    This is the same curve, as viewed from the opposite end.

    Even this curve, through the industrial area of Dunnville, is superelevated. The speed limit here is 20 mph for freights, and only 10 mph for passenger trains, due to the tight curves, and again, it's on a grade.

  9. KCS

    KCS Member

    I would be affraid of standing next to a stopped freight that's a mile long with light cars in the middle on a section of super elevated track. The way I look at it, weight + height + lean + gravity=............ Well, if you add in "pull force" for the train movment starting out and gravity on an incline would pretty much means "tip over" I don't know if this is true or not because I guess it's possible but I've never seen a train stopped on such a curve so I really don't know but it seems plausible to me. As for modeling goes I highly doubt that can happen unless you have an 80 car long train that jerks into a start and pull's every car off the track that's in the curve. :)
  10. Dick Elmore

    Dick Elmore Member

    We tried it in a couple of spots on the club layout and I couldn't get my long passenger cars around them without derailing. If the cars are 85' and they're close coupled, then they tend to bind.

    Texas Chief
  11. LongIslandTom

    LongIslandTom Member

    Just want to share some prototype pictures of the sharpest curves I've ever seen, with superelevation...

    NYC Subway, #7 elevated line (AKA Flushing IRT). Notice how they superelevate the curves, with wood shims 2-3 inches thick between the rail and the tie.

    And this is above a busy street, 40 feet in the air! And I have been on the train a couple times during rush hour, with heavy traffic congestion, when it's STOPPED on the curve, at rest at an angle. :D

  12. eric halpin

    eric halpin Eric Halpin

    super elevated track

    Thanks so much every one for your comments. I shall do this elevation on my 18x21 walk-in layout. Starting the walls tommorrow.
  13. pgandw

    pgandw Active Member

    Super-elevation by itself will not cause the string-lining (tipping over inwards on a curve) effect. String lining happens on flat or super-elevated curves if the cars are too light, or the cars are too long for the radius of curves being used. Cars with poor rolling trucks at the rear end of a long train practically guarantee string lining.

    The easiest way to prevent string lining is to use a curve radius at least 3 times the actual length of the longest car, and have all cars weighted to at least 75% of the NMRA recommended practice (assumes all trucks roll decently). I have never seen or heard of string lining where these 2 practices were followed (especially the curve radius).

    Note that this means a minimum radius of about 36" in HO (and 18-19" in N!) to run full length passenger cars. All that will go around an 18" radius curve in HO without eventually encountering string lining at some longer train length is scale 40ft cars.

    my thoughts, your choices
  14. LoudMusic

    LoudMusic Member

    Is super elevated track realistic for logging lines? Specifically ... narrow gauge? Cutting to the chase, should I do this on a 12'x12' On30 layout?
  15. eric halpin

    eric halpin Eric Halpin

    Good info. Thanks
  16. fsm1000

    fsm1000 Member

    Loudmusic, yes if it is a m'modern' one with good track. If it is one of those made by loggers with rough track and no idea what they are oing then no.
    If you can get a hold of a book called 'logging in Canada' or 'Logging in the northwest' [I think that's what it is called], about logging on Vancouver Island, you will see that the bigger and better ones used all the tricks where as the smaller outfits just threw track down using logs for ties and no ballast. The two extremes.
    Anyhow, it depends on how modern your old logging road is.

    Hope that helps. :)
  17. Jim Krause

    Jim Krause Active Member

    LoudMusic: I don't think speed was much of a factor on logging railroads. Keeping the trains slowed down was much more of a problem so super elevating wasn't used except where they wanted to tip the logs off of the cars at a log dump. I have seen pictures of some tight curves that looked like there was banking but it was probably just because of low tech, temporary operations.
  18. Jim Krause

    Jim Krause Active Member

    LoudMusic: Let us know how that On30 layout is going. I'm a wannabe On30 modeler. My "layout" now consists of a 1x10 pine board, sitting on a shelf, with the Peco track temporarily nailed to it so I can display my On30 equipment. There is an On30 group near here that just started a modular layout. That may be the route I go.

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