I am working on an N scale layout. Min radius is 16". How much should I elevate the outside rail for a proto look? .010 - .020 inch sound good? Maybe just test it out on the bench until it looks good?
Jon
For your scale, I wouldn’t go higher than the first/lower number you listed.
-Crandell
As you said, test it out on the bench until it looks good - - and runs good, that is the key. Once you get it right, at least to your satisfaction, make some notes on the superelevation you settled on for future reference. That’s the way I did it - - in HO scale.
Rich
Not to hijack this thread, but how did you guys super-elevate your curves? OP, how do you plan on doing it?
In the early twentieth century at least, super elevation was normally limited to a maximum of 6 to 8 inches. Unfortunately, only if train speeds are uniform can an ideal amount of superelevation be determined. Excessive superelevation creates additional train resistance. “An instance is recorded where two engines hauling 3500 tons of coal on an 8-degree 30-second curve with a central angle of 185 degrees habitually stalled when the super elevation was 5.5 inches, but when it was reduced to 3 inches, no further difficulty was experienced.” (Williams, Design of Railway Location, 1924)
Superelevation for our models is merely for appearance, not operation. When used, it should be no more than what is noticeable yet subtle. Too much superelevation can cause derailments, particularly where the transition to/from superelevation isn’t smooth and gradual. Also, superelevation creates a greater opportunity for “string-lining” (cars flipping into the inside of the curve) on long, heavy trains.
Mark
Basswood shims of varying thickness under the outside edge of the track, underneath the ballast.
I would tend to stay closer to the .010 side maybe .015 anything higher and your going to look like a NASCAR track. I use Evergreen scale styrene strips glued to the bottom of the ties
Well 3 inches in N scale is .01875 inches. I think I will keep it to a max of .010 at the center of the curve.
To the poster asking about how to do it. I am going to super elevate the sub road bed using 1/4 inch plywood and 3/4 inch pine for the risers.
I misread your question. I read 1/10th of an inch rather than 10-20 thousandths. Please accept my apologies.
Somewhere near 3-5" in scale difference between the inner and outer track would be fine, but please, no more than that. It just doesn’t look good, and may actually give you problems in a few cases.
Methods are many. Use strips of masking tape, stepped in from each end by maybe 3/4" so that you get the transition into and out of the superelevation. The strips would be near the outer edges of the ties, and stuck onto first the roadbed and then each other.
Some companies make superelevated track…I forget which.
Styrene is used by some, cardstock shims, sanding/planing the inner roadbed or the tie ends that will be innermost along the curve and elevated portion, and spline roadbed users probably effect a lot of their superelevation by actually tilting the splines on their risers, which themselves are tilted and screwed into their supporting frame members at angles that impart the desired superelevation to the roadbed they support.
-Crandell
Are you saying that you are creating your superelevation by tweeking the 1/4" ply to gain the bevel for superelevation? You will have much better control of the easment and the actual amount of superelevation by shimming. Twisting plywood, especially, 1/4" by the risers may cause unwanted or uncontrolled waving of the plywood. This could be even more unstable during damp or humid conditions. A solid subroadbed with the roadbed or the track shimmed to the superelevation would be the better method in my opinion.
Actually, off-setting the bottom of the risers gives you great control over the amount of superelevation, and, properly done, will give you the vertical easements in and out of the curve automatically, with no mathematical calculations required. I use 3/4" plywood as my subroadbed, but if the 1/4" stuff remains stable on a non-superelevated curve, there’s no reason that it would change if superelevation were introduced.
It took some searching, but there’s more info on adding superelevation HERE. If you scroll down far enough, I outline my method for achieving it, as mentioned above.
Wayne
So if you have a curved steel viaduct and girder bridge would you ever superelevate or is the risk of “string-lining” (new word for me!) just be too great?
Eric
A nice and easy way to super-elevate curves in N scale is described here.
The guy uses various layers of masking tape, staggered to achieve a smooth transition. Worth looking at!
Eric, trestle decks are/were superelevated, but the amount would be judicious. It would be better to have passenger trains slow over a section due to ‘insufficient’ superelevation for their speed otherwise on a given curve, than to have struggling freight trains leaning heavily on a bridge. However, I have photos of trestles with superelevation, but just a subtle amount, maybe 2". On level decks of modern trestles, where superelevation is still desired, the ballast is adjusted accordingly. Many modern bridge decks are ballasted the same as gravel roadbed.
-Crandell
Eric, if you go to the link which I provided, you’ll see that not only is the bridge superelevated, but so is the “S” bend leading into it. While the speed limit here is 35mph for up-bound freights, most will be lucky to achieve 20mph, as the grade is 2.5%. I also run some heavy (but short) coal trains here, with “live” loads. Until scenery is added, the drop to the concrete floor (almost 5’ at its highest point) is on both sides of the track, but I’ve never had a problem with a train stringlining, and that also includes trains over 70 cars long.
Wayne