I am going to “super elevate” the curves on my layout. It seems like a simple idea - put shims under the ties to prop up one side. Does anyone have any insight on this. Something that seems so simple usually has a few unforeseen issues.
Any help would be appreciated.
Sean
Sean,
That’s what I did with mine. I used strip styrene under every 10th tie or so, starting with 0.015" at the beginning and end of the curve, and going to 0.030" in the main part of the curve. It’s very subtle, and I’m not sure it’s superelevated “enough.” Maybe I should have went with a little thicker shims.
Another idea is to use layers of masking tape on top of the roadbed like this guy does:
http://www.thecbandqinwyoming.com/CM%20-%20Super-Elevating%20Curves.htm
Placing a shim every tenth tie, or so, will result in a a wavy track if you are running any kind of heavy equipment. The best method would be to run a wire or string underneath the outer rail to achieve your superelevation. If you are running long wheelbase steam locomotives or eight wheel trucks, it is best to not allow the elevation to drop until you have straightened the curve out for a full car (or locomotive)length. Also, you cannot have turnouts on superelevated curves for the same reason. Long rigid wheelbases and tilt changes on curves just invite derailments.
Taking carstock and running it through a paper shredder should provide you with lots of flexible shim strips.
The amount of superelevation you can use depends on the radius of the curve. If you layout is using 48" radius curves, you can super elevate as much as the prototypes. Most layouts have 24" or so and this is a problem if you try to pull long trains over the elevated curves as they will straight line under hard pull, much like the real ones do on hills and curves. Happened to the old SP many times on their hills and curves.
You did not state the radius of the curves, but you could increase the elevation above .030 if the curves are large.
How high would you superelevate the curve for 22’’ radius??
This is N scale, but I use .010" styrene shims on the easements and .020" shims in the curves.
About the thickness of two playing cards, James, perhaps three if you want it more pronounced.
Appreciate that selector [:)]
In my last layout, since dismantled, I used 30 inch minimum radius curves throughout, with spiral easements, and superelevation in curves. Through experimentation, I found that anything less than 1/8 inch elevation is not noticeable enough to be worth the trouble. Maybe 3/32nds at smaller radii, otherwise don’t bother. Do a sample section, as I did, and trial and error it to suit your own amusement and amazement. Secondly the begining of the superelevation should begin on the tangent far enough back so that it is at fall height at the beginning of the spiral easement segment. Railroads don’t start the superelevation in the curve and you will get much smoother operation by starting it before the curve. The engine gradually leans into the curve and hits into at full “tilt” literally and figuratively. It is a sight that gave me a thrill every time. I cut tapered pieces of 1 x 4 wood from 0 to 1/8th inch about 12 or so inches long and slit them about 1/8th inches wide. I placed these flush with the outer edge of the ties and then used wood putty (I think it is called Johnson’s, the kind you mix from a powder) and spread it with a putty knife . It hardens like a rock and doesn’t sag or crack. Use a long sanding block and get it smooth before laying the track. I used good ole Elmer’s white glue.Use 1/8th strips thoughout the curve. In my opinion this is one of the things that makes it look like a real railroad and not a toy train outfit.
If the 22" radius is N scale, you can use about .020. I would not use super elevation for HO unless you have 30" radius curves or greater. That is just a rule of thumb and depending on your operation, some super elevation could be used below 30", but it will tend to cause longer trains to derail on the curves. If you have short trains, it will probably work with a small amount of elevation… Modern day railroads do not use super elevated curves as high as they did in the late forties and fifties.
Why is this??? Passenger trains ran at much higher speeds and the basic steam locomotive had a much higher center of gravity.
Large steam would not attempt to restart an extememly long train directly on a tight curve if it was super elevated. They would back around the curve a little distance and come around the curve already moving. If they had helpers on the rear, this problem is usually lessened by the helper power starting first and removing some of the resistance on the curve since the train is not all hanging on the lead engine.
Perhaps I run too much super, 1/16 strip of balsa under the elevated rail. I start a very gradual start about three or more cars so that my SD45T2 will stay on track, is my worst unit add makes for a great track tester.
It’s HO and my biggest loco is a SD45T-2, I might try it and see if it looks good and works well…thanks for that information.
There was an article in MR a while back on this. I did mine w/ 3/32 X 1/8 stripwood. The trick is to use a long and gradual transition. I believe I sanded my strips from 0 to 3/32 in 18 to 24 inches. My curves are 48" and 72" (oh! the joys of lots of space) and the super elevation amounts to 8" and it is a real joy to watch those psgr trains lean into an S curve w/ 6 feet of tangent between them.
I have to agree that super elevation of curves really does make a difference in looks and makes a model railroad look more real.
The amount of 1/8 inch of elevation is equal to one foot in height, if I am thinking correctly. This must have caused some problems in operation of twenty to fifty car trains unless they were weighted double the amount for the NMRA standards. Your comments on beginning back some distance is a very good example of doing it right. The super elevated rail should
Jeff Wilson’s track-laying book makes the following recc. (HO)–start with .01" thick styrene strips on the beginning of the curve–length should be distance of your longest car (about 8-12 inches). Then use .02 inch thickness strips for the next 8-12 inch section, then use .03 inch strips for the thickest section (which should then be continued to the middle/top of the curve); mirror image this arrangement on each side. Strips should be .100 inches wide. For N-scale, he recommends .06–.08 inch wide strips, and the thickness of the strips should be 1/2 that recc. for HO, i.e. .005, .010 and .015 inches.
Jim
Sean,
I’m glad that you brought this topic up, I too need the low down on this information. If you have been receiving the MR for some time now then you probably have the one that has Pelle Soeberg’s article about his layout’s track. He mentions what he did for his “Super Elevated” curves. If you don’t have the article, let me know and I will PDF it to you via email. Pelle’s looks great!
Superelevated curves are lovely to look at, and no problem to operate over. The problems crop up at the place where the superelevation is changing from nothing to something, or vice versa. If the transition is too abrupt, you will shortly find out which rolling stock is too stiff to appreciate it!
I personally superelevate 610mm (24 inch) radius curves about 2mm (measured at the ends of the ties, not under the rails,) and taper the superelevation to match my horizontal transition curves - no superelevation at point of actual tangency, 1mm at point of theoretical curvature (where the tangent would meet the circular curve it it wasn’t offset 12mm to the outside) and 2mm at point of actual curvature, where the spiral easement becomes circular curve. Looks great, and operates well once the rolling stock has been adjusted to accept it.
Much has been written in the engineering press about how much superelevation is enough, or too much. (This applies to highways, too. Note the difference in camber between a 110kph freeway and a 70kph country road, and the total lack of same on city streets designed for a maximum of 40kph.) The ideal, never realized, is to make a plumb bob inside the vehicle stay over the precise point it was over when the vehicle was standing still on a perfectly level parking lot. The showgirl at the church social is that not one vehicle in ten thousand will round a curve at the precise speed calculated. Some (coal drags and lumbering RV’s) will be slower. Others (Acela, anything with a J at the point, Joe Harley, The Little Old Lady from Pasadena in her chopped and channeled muscle car, or an 18-wheeler pilot with time-sensitive cargo) will be faster, often a LOT faster. Thus, of necessity, superelevation in the 1:1 world is a compromise.
Since gravity does NOT scale down, model superelevation is purely cosmetic unless you consider the old Athearn Hustler to be a drag engine! It is unl
Superelevation of 1/8" in HO is 12", which is on the extreme side. For the prototype, 6" of superelevation was more like it, and that’s what I use mostly. I’ve done a bit of 3/32" too, but it can start causing some extra stringling effects on long trains, making it more likely they will pull things off the track to the inside of the curve.
You may not notice 1/16" superelevation as much as 1/8" when looking at the layout in person, but it shows up dramatically in photos. Here’s a couple of examples.
(click to enlarge)
(click to enlarge)
The last location was an interesting challenge to construct because the superelevation is across a curved trestle bridge. I laid the track, with basswood shims under the outside edges of the curve, on regular roadbed around the curve, then did a pencil rub tracing of the rails on some paper pressed down onto the rails where the bridge needed to go. Then I cut out the roadbed and removed the ties in the location and just left the rails hanging in mid-air.
I scratchbuilt a curved trestle out of styrene using the pencil tracing of the rails. I built the trestle level without any concern as to whether or not it was on a superelevated curve. When I put the trestle in place, I tilted it slighly to fit the tilt of the rails, and spiked the rails down to the top of the trestle (I used a basswood tie for every 5th tie so it would be easy to spike to).
And it worked great! I got a superelevated curve across a wood trestle, and it shows up especially well in photos. [swg]
Two additional notes: I have more luck placing shims under the roadbed, rather than the track itself. Seems to be smoother, and if necessary you can then adjust a bit with a very small shim under the track. I usually use card stock, posterboard, etc., in two sizes – the thinnest for the first few inches, then the thicker. Especially with foam roadbed on plywood, the foam smoothes things out nicely even if the shims aren’t all that precise. Do be extremely careful if you have a curved turnout – you CAN superelevate it, but you have to keep the branch flat with the main for several inches. I have a couple of crossovers on a double-track main . . . the whole outside main is higher than the inside. It works fine, but took a while to get adjusted so it would!
Your pictures look extremely good and do show the super elevation much like it should be. The numbers you used seem to be correct as 1’ is too much super elevation for prototypical operation .
Thanks. Nice shots. Show us more if you don’t mind.