I'm just starting a new layout that I'm using 32" easements into 28" radius curves. I want too use superelevation on some of these curves but I don't know where to start. Do I start at the beginning of the easement, mid-point, or somewhere else for the best (and most protypical) results? Any suggestions?
Skip the superelevation. It just does not work well in modeling. As far as easement, it is not a radius. It is a spiral curve. It starts at "0" radius and gradually gets to your required curve. That is why they call it ease as in easement. If you are in the design part of the layout, just add a few inches prior to the curve to work it in. I will look around and get back to you for the best way to do it.
The use of a large French Curve is good for setting up easements Willie .. especially on your layout plan drawing.
Sorry, but I've got to disagree on the superelevation. If your prototype has noticable superelevation, then you should consider the same for your layout.
My single spiral helix is superelevated and it works great. Most train layout curves are to tight to use superelevation. It only looks and works right with large curves.
Define "large" curves. My layout is going to have 36" to 38" radius curves on the mains so that my 85' passenger cars will look right. The layout isin't big enough to have anything but terminal trackage, so high speed isin't an issue, but the next layout will.
Super elevation and easements have to do with speed to help keep the center of gravity more toward the center line between the rails. There are differing amounts of elevation. If you are going to run double stacks, or passengers at high speeds, then the elevation will be greatest at the apex of whatever curve you maintain road authorized speed through. On a model, the forces will probably stringline your cars if you have too much elevation and go too slow, or try to start up with the middle of a string of cars sitting on this curve. Most high elevations are on predominately down grade running where speeds can get touchy, especially on passenger runs and long heavy freights way out on the mainline. Elevation actually assists getting around the curve, similar to the "leaning" effect on the front wheel of a bicycle. That is also why the outside rail on a curve is heavier built than the inner rail, to carry the greater weight. Elevation starts on tangent track before the easement starts, to prevent the "lurch" and compensate for centrifugal forces when rounding the curve. The weight increases causing the truck springs to be compressed gradually more than when on straight and level track, then is gradually released as the curve straightens back out again. Going round a curve at 15 miles an hour has almost no effect, but hitting the same curve at 75 the "lurch" can actually be felt if the train is running over the recommended speed for that curve. It is what made your Lionel toy train always jump the track at the first curve with wide open throttle! The thickness of a credit card is about right for an 18" radius curve on HO and half that on N, because you aren't going to be running at high speed through that tight a curve, but there are some real super elevated track that measures as much as 6" across the rails at a curve apex! The whole idea is to make it gradual, if you need it. If you are running the rigid trucks made today, super elevation will probably hinder your engine's ability to maintain electrical contact, rather than help. Elevation twists the track, which means you only have a three point suspension, instead of 4,6, or 8 wheels touching, unless you have sprung or equalized suspensions. Easements will do you far more good than elevation on a model layout unless you are running up around scale 75 or 100 scale miles an hour with top heavy rolling stock.
You need to get a copy of John Armstrong's "Track Planning for Realistic Operations", published by Kalmbach, and read it cover-to-cover about three times! It describes a pretty simple way to lay out easements (and also says that superelevation is more trouble than its worth.) Also, a "nit" correction to one of the earlier posts describing easements - they don't start at a 0" radius, they start at an infinite radius (aka a straight line) and decrease to the radius of the curve. [ 25 February 2002, 14:11: Message edited by: Bill Kamery ]
Superelevation gives a nice effect for curves of 15" or greater in N-Scale. Shim the roadbed on the outside of the curve with a few layers of business card stock.
I have superelevated 30" radius curves on my layout, they cause no problems. I handlay, but this method would work with flex track. I detrmine where the tie will end on the outside of the curve, and draw a line. I glue wooden ties along this line. The superelevation ties start about 6" before the curve starts. They are sanded to provide a gradual ramp up. tie thickness is between 1/16 and 1/32. If using flextrack, just lay it so the outside end of the ties rest on the wooden ties, they will be invisable after ballasting. The look of the right of way, even without train, is well worth the effort. Gary
Being the "practical simplifier" that I am, I've come up with a simpler way of doing easements than the "correct" way of doing it. I know it's not prototypical, but it works for me. First, determine the absolute longest piece of hardware that will be traversing your layout. This will likely either be a long passenger car or a locomotive. The articulateds are especially long. Second, install the first section of track at least that long at twice the radius curve of your "ruling" curve. For instance, if you have 28" radius curves, you might install 18" of 56" radius curve before you dive into the 28" radius curve. I've drawn it out and this will increase about 1" to the total radius of the curve as far as layout planning is concerned. It also means that the curve will start about 18" before you were planning on it. Granted that 18" of a 56" radius curve will look fairly straight, but that's the idea, right? What this means to the running train in this example is that the transition into any curve will be no more than a 56" radius curve. Mark
I think superelevation looks good in the right setting, but obviously has some downsides. I did it on an N scale layout many years ago where I was using a soft foam ballast (Peco track in Peco underlay). The track was pinned through the foam to the board and on the curves I offset the pins to the inside of the curve - in fact actually on the outside of the rails where I needed a lot of cant. I was then able to adjust the degree of s/e by how far I pushed the pins in, or pulled them out again.
I have some superelevation on my layout, around 12" radius "S" curves on double track on a 3% grade, with no problems whatever. It is not much, but it certainly looks better. I used narrow strips of breakfast cereal packet under the outside rail.
slimjim, I appreciate both your reply and the link, and everyone else for their input. Since I don't need the SE for operational purposes, I'm now only going to use it on a small section that will be at eye level. As to ten87's comment, I model the Santa Fe and they certainly used it here in Texas.
I'm not sure if the original question was ever answered - start the superelevation transition with your transistion curve. The transistion should be at least as long as your longest piece of rolling stock - ideally it should be twice as long.
I plot the spiral using autocad then plot it out full size on 24"x36" sheets with several images across the sheet. Tick marks keep each image in alignment to the original tangent ending at the center of apex. On the layout, I tape the sheet in alignment, then slip carbon paper under it and roll a transfer wheel along the line. This transfers the mark directly onto the layout. If I make an easement, I use stacks of paper so the thickness (.003") is gradual. Most of my rolling stock is equalized or sprung so there are never any problems like there would be with a solid wheel base 4-8-4 steamer. I start the elevation about 12" before entering the point of tangency, the greatest at the apex, and back to level at the other point after the curve. (I have since been given and purchased some Rivarossi engines that are not as yet equalized, but they have not given any problems so far.) The greatest elevation my book calls for is 6" at an 85 mph apex on an 8 degree curve in real life. Because it is fuel effecient, the inside rail drops below grade going into the curve on down grade track, and the outside rail drops down to grade coming out of the curve, but this is predicated on one-way traffic running down hill. Other curves for two way traffic, elevation from grade is only on the inside rail and seldom more than 4". [ 10. March 2003, 20:15: Message edited by: watash ]
Does anyone have a picture of a train on their layout in a curve demonstrating super elevation? I could not find any thread with such a picture. Thanks.
As was mentioned, the prototype uses super elevation to counteract the effect of centrifical force. On the model it primarily becomes a matter of cosmetics. To me, the results are well worth it. I use masking tape under the outside edge of the track and slowly build up the layers towards the center of my 22" curves. Works fine and looks great.
