What are the rules on superelevation on railroads? What determines the use of SE? I realize speed is the main concern but when would a railroad apply its use? Would a sharper radius cause any difference in application? What about less than mainline trackage?
Thanks,
Roger
This is only my opinion, based on what I think I have seen when I am looking for the effect:
It appears to me that railroads do superelevate, and that they do it in most curves. Naturally, the tighter curves where the trains are also meant to be moving quickly will have more superelevation. It would be a disparity of about 2-3" between the inner and outer rail at the apex of the curve, with the disparity easing to nothing at the extremities.
It can look really good on a layout, particularly in images. I have often seen it overdone, but I have seen it done very nicely. Doc Wayne has managed to achieve a credible effect, whereas I, in my "youthful verve", overdid it somewhat on my latest layout...at least in some places.
In the "Community Search" function at right, I found this recent thread. There are several others.
http://cs.trains.com/trccs/forums/p/135563/1529467.aspx#1529467
This is an example of where I wish I had less. Maybe I'm just a bit squeamish about this shot....dunno.
Now THAT'S superelevation!
I love it. On my last layout I glued 1/8 x 1/8 balsa strips along the outer edge of the ties. I started at the beggining of the spiral easement and continued to the end of the other spiral easement returning to the next tangent.
I tapered it up with a sanding block from zero at the beginning and leveled it off a few inches into the curve itself. While this is close to a scale foot, it is the EFFECT that you are looking for, not the replication of the prototype.
Nothing looks more toy train like than a huge steam engine going flat footed around a curve.
Federal Safety Rules permit a maximum of 7 inches of superelevation, but most carriers use between 3 and 6 inches dependent upon certain factors:
1. Curve radius
2. Curve Sprial or easement
3. Curve "runoff" or the transition from cross-level and tangent track to full superelevation
5. Speed of track, FRA track classification and expected maximum tonnage
There are other factors to be sure, but this should help.
I use .010 styrene to begin a runoff and go through .015 to .020 for the full easement, which if my feeble math skills are correct, simulates a little less than a 3 inch easement, perfect for a 30 to 40 mph secondary line such as I model.
In HO, Precision Scale Co. makes 3 ft flex track that is already super-elevated: there are nubs under the ties on one side. Heh heh obviously you have to remember to curve the track the correct direction or hiliarity will ensue! I trim the nubs from the end that will meet the tangent so that the superelevation is gradual. It is nice looking track by the way, but a little hard to curve, so the Ribbon Rail track radius gauges are a big help here.
Dave Nelson
Was just about ready to lay some ballast when I started reading this line.
Got out my digital caliper and lo and behold, a playing card is exactly .01 in.
Guess I will be cutting up some jokers tomorrow. I can't see that a playing card with plastic
coating should interfere with glue/water mixture, or would ever deteriorate. Plan to
loosen my nails though, from what others have written.
st
I use 1/16" cardstock (scale 5.44") cut 24" long by 1/8" wide on a large paper cutter. Using a SHARP drywall knife, I carefully shave the ends that go under easements to zero thickness over a foot or more of length. Works very well on the main lines with 33" and 36" radius curves.
Karl
The mind is like a parachute. It works better when it's open. www.stremy.net
I am planning on using spline roadbed made with 1/8" thick Masonite splines. I have read a few articles describing how to implement superelevation by raising the outside spline by the height of the superelevation at the "creast" of the section of superelevation. This way, you will get a nice natural easement as the spline rises up from the beginning of the curve to the peak and then falls back down at the end of the curve. Jamie
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selectorIt can look really good on a layout, particularly in images. I have often seen it overdone, but I have seen it done very nicely. Doc Wayne has managed to achieve a credible effect, whereas I, in my "youthful verve", overdid it somewhat on my latest layout...at least in some places.This is an example of where I wish I had less. Maybe I'm just a bit squeamish about this shot....dunno.
Thanks for the kind words, Crandell. Your scene looks just about right to me - not excessive at all.
I found it easy to make superelevated curves on my layout. Most of the sub-roadbed, and all of it on the curves, is cut from 3/4" plywood - I simply layed out 30" radius curves on a sheets of plywood, then a 32", 34", etc. until the sheets were used up. I then joined as many sections of a suitable radius as I needed for any particular location, then placed it atop the open grid benchwork. After aligning the ends with the already-in-place roadbed on either end of the curve, I marked the underside of the curved roadbed at each crossmember and installed risers to the underside of the curved roadbed. Next, I placed the curved section at the proper elevation and fastened the ends to the in-place roadbed, then adjusted the elevation of the balance of the curve, clamping the risers to the benchwork crossmembers - the curve can be level, or on a grade, it doesn't matter. Each clamped riser then needs to be marked with a pencil, the line across it denoting the top of the crossmember to which it will be fastened. Next, remove the clamps and select the riser closest to the mid-point of the curve, pushing its bottom end towards the outside of the curve. This will cause the outside of the curved roadbed to be elevated - "eyeball" the degree of superelevation, align the end of the pencil mark on the inside of the curve with the top of the crossmember, and clamp the riser in place. You should be able to tell if the superelevation is right just by looking at it - if not, put a loco and a few cars on the curve and have another look. Adjust the offset of the bottom of the riser towards the inside or outside of the curve, as required, until it looks right, then fasten the riser to the benchwork with drywall screws - make sure to line up the inside end of that pencil mark with the top of the crossmember.
With the bottom of the middle riser offset and fastened in place, the bottoms of all of the intermediate risers will also be offset, to varying degrees, with the offset decreasing as they get farther from the mid-point of the curve. After carefully aligning the inside end of each pencil mark with the top of its corresponding crossmember, fasten the risers in place, taking care to neither increase or decrease the offset of each, as this is the easement into and out of the curve. It's actually easier to do than it is to describe. While my trains usually don't exceed 45 mph, it's still neat to watch them enter the curves, gradually heeling over as they progress to the mid-point, then gradually righting themselves as they exit the curve.
You can even add superelevation to your bridges - this one is on a wide "S" bend, coming out of the long curved (and superelevated) grade - a long train going through this series of curves is really fun to watch:
In my opinion, superelevation of curves is probably a lot easier to achieve with plywood roadbed on either open grid or L-girder benchwork than it is with a tabletop style, using either plywood or foam sheets.
Wayne