In many of the discussions on minimum radius for curves and installation of turnouts there is much talk of the use of easements. I understand that easements help with the “appearance” of the train as it moves through both but can someone please explain a little better what exactly an easment is and where you would install it? Is it a small section of straight track in the middle of the curve? Also, where and how would you install an easement on a turnout.
Thanks.
an easement is just a slight elevation on the outside of a curve. I would put them in the curves with a thin strip of styrene under the outside edge of the roadbed
Jeff
An easement is at both ends of a curve and is where the rail begins a more gradual entry into the curve than the radius at the center part. Elevation of the outer rail is called “super-elevation” and is not the same as an easement.
Even highways use easements into the curves if at all possible to make steering into the curve more gradual and easier to negotiate. The next time you’re out driving on a major highway, notice how, as you enter a curve, you have to gradually turn the steering wheel more and more to stay in your lane. That’s easement.
Interestingly enough, you can use an electrician’s conduit fi***ape to form easements on your curves. Pin the ends of the tape down where you want to begin your curve using push pins, leaving 2 inches or more of straight section at each end. Move the tape in or out at one end until the center of the curve appears to be where you want it, and then trace the tape’s outline. The tape will have formed perfect easements at the ends.
I make my templates out of 1/8" door skin veneer cut to about 6 or 8" wide. Look up John Armstrong’s book “Track Planning for Realistic Operation.” Page 73
Starting with 6" of tangent (straight) I lay out the first L/2, the offset, and the second L/2. I have also a master rod with a center hole and pencil holes at various radii. From the offset point I swing the desired radius. These templates are for the track centerline, handy to use anywhere, and are easy to use a fine point sharpie pen to mark the roadbed material. For HO I use the following values:
Radius L/2 Offset
36 9" 1/2"
48 10 1/2" 5/8"
72 12" 3/4"
Use the values in the book for smaller radii. They really do make a difference in performance as well as appearance.
jhoff310, what you’re referring to is superelevation. Easements are a slight curve prior to the main curve.[One way of putting it]
Easments also help with operation. Because the transition from straight to curve is less abrupt, equipment tracks better. Because equipment tracks better at the transition it will negociate a sharper curve than would otherwise be possible. The allowable reduction in curve radius is more than the transition off-set. This can save space on a layout. Especially helpful if you want to run big locos and/or long cars
An easement is an increasing change in curvature from the tangent to the radius of the curve. It should also be used where curvature changes from one radius to the other. Unlike super elevation, easements do help on model railroads. The railroads use a cubic spiral formula, but there are several simpler methods for model railroads as noted above. You can even get an easement effect with sectional track by using a larger radius curve for the first piece, i.e 30" radius piece leading into an 24" radius curve.
Enjoy
Paul
My apologies for the mis-information I wasnt thinking clear. thanks for setting the record straight
jeff
Question: I remember reading an article about using the spline method for laying your curves and that it has a natural easement at the beginning and end of the curves exactly the same as using electrician’s fish-wire would do as mentioned in the first post above.
I was thinking about using the spline method on two critical curves that I want to get right. Am I thinking straight here, guys?
-Dave
Yes, the spline or batten method is the easiest as long as you can secure it about 6" at each end (tangent and curve). Remember the offset is for the radius line and the easement splits it halfway between. example: for a 1/2" offset, the easement line would be at 1/4" between the tangent line and the start of the radius line. The book has a good picture and once you have done it, it will become second nature to do it for all curves.
Thanks, John. I’ll need to hunt down a copy of the book
http://www.trackplanning.com/easements.htm
This page is very helpful.
Gents,
Thanks very much. Your comments and the website got me straight. Appreciate the help and love this forum.
Dave