I’m planning my first N scale layout and I heard that it is a good idea to include easments entering curves and grades. I have 15" minimum curves and I was wondering what a practical easment radius would be. Also how do I calculate a good easment for a 2% grade? Thanks for any help.
If you have the room, vertical easements should be roughly a car length of your longest car for every per cent of grade. Shorter vertical easements have been used successfully, but still need to be at least 1 car length to be of any real benefit. You just have to watch for vertical coupler mismatch, which might cause the train to come uncoupled if the change is too sudden. Vertical easements are automatic if you use spline or cookie-cutter (bent plywood) subroadbed to form your grade.
For curves, a better easement is one which involves not a circular curve, but something like a bent piece of thin wood. The radius in the easement is continually decreasing (starting from infinite - straight - if possible) to the 15" radius of your curve. If you use a “springy” flex track that is one piece, including part straight, you will also get automatic easements for your curves. For curves, to be of much value, the easment must be at least one car length long.
my thoughts, your choices
Fred W
Hello CSXFan, The November “Model Railroader” will show how to lay out easements with the bent-stick method, in an article I’ve written on track and coupler standards for model passenger stations. (For immediate reference, it’s the same method shown in John Armstrong’s book, “Track Planning for Realistic Operation, page 116 in the Third edition.) For an N scale 15”-radius curve you could use a 10"-long easement offset 1/4" from the center line of the circular curve, or 15-1/4" from the center point of the curve. With this method you form a transition curve of gradually decreasing radius through the length of the easement, so there’s no set radius I can specify. For vertical curves, the transitions at the botom and top of grades, my method has been to rely on stiff plywood subgrade or subroadbed material. For N scale, if you use 1/2" thick, 5-ply plywood for your subgrade, you probably can’t bend it sharply enough up or down to cause problms with veritcal curves. Anchor the level section, bend the plywood to the desired grade, and let it form the transition naturally. Vertical curves can be an issue, but if your subgrade material is stiff enough you won’t have to worry about it. Good luck, Andy
Thanks for the help, I probably won’t start construction for a while so I can wait for the November MR artical.
Just one more question, is there a curve radius that would look okay without an easment?
For N scale you could go with no easement on anything 30 inches or larger as visually it’s hard to see when it gets that large, but for operations it always helps to use them. On my last layout (N scale) I had a 40 inch curve with no easement. Visually it looked fine, and at low speeds there was no issues. When I was highballing it through there though, you could see some minor “lurch” to the cars as they headed into the curve. An easement would have helped cut down on that. Superelevating the curve would also have been a good idea. Guess it’s a good thing I’m starting over, huh? I’ve got a brand new train room that’s bigger then the last being built right now. Ahhhh, a fresh slate! I’ll be right behind you on the construction process.
I also model in N scale and used the easment formula from MR. My smallest radius is 27" and when drawen out it looks like it does nothing but I was told “do it now or you’ll be sorry” . All of my curves run great and it takes only a minute to do. I did the 1/4" at 10" long … so does it have to be done to work right? At the price of track and turnouts I wasn’t a gambling man!! Hope this helped.
Guy
27"-40" minimum, HA!, I wish! I thought I was doing great with my 15" minimum. I don’t follow the 1/4" at 10" long formula, could you please explain? Thanks for the help.
If you can find an old MR magazine (1/04) or John Armstrong’s book it will have pictures but I think I can explain it without drawings.
Draw a line that would be the straight track approaching your curve.
Choose your radius, but offset that line 1/4" to the inside of the curve, and draw that line
So you should have two lines that don’t touch. At the point where they are closest (1/4") make a mark at 1/8" (the middle) and from that point measure 5" straight in both directions (10") and make marks on the straight and on the curve. Bend a stick to hit all three marks and you’ve got your easment. The sharper your radius the more you will see what you’re trying to accomplish.Your cars will ease into the turns as opposed to slamming into them, it doesn’t look like much but it does make a difference.
Guy
Thanks a lot for the help, I think I understand now. I’m going to be gone this week but when I get back I’ll try it and report back with my findings. Thanks again!