The diagrams on this page were made using an N scale Kato Unitrack template in the RailModeler track layout software package.
01 of 06
What's an Easement?
An easement is a railroad track laid in a parabolic curve. This means that its radius decreases as you approach the middle of the turn and increases as you move farther away from it. Unless you are using flex-track, model railroad track curves have fixed radii. This means you can't build a true easement. But you can simulate an easement by placing segments of smaller radii inside of segments with greater radii. The "easement" examples on this page are all simulated easements made using segmented track curves.
You seldom, if ever, will find a semi-circle turn on a real-life railroad line's tracks. Building easements in our layouts are one of the techniques we can use to make our layouts more realistic.
02 of 06
Model Railroad Track Easements and Layout Space
Easements can reduce the length required to turn your trains around. This can be a good thing when your space is limited length-wise. The other side of the issue, however, is that easements will increase the width required for turning, not necessarily a good thing for a narrow layout.
03 of 06
Semi-Circles Don't Look Realistic
A semi-circle is a 180-degree turn that has a constant radius. When you buy a train set, you get several straight track segments and enough curves to make two 180 degree turns. These are used to make what model railroaders call an oval. Strictly speaking, this isn't really an oval; a true oval has no straight line segments. (See geometry reference links below).
04 of 06
Making Easements With Forty-Five Degree Curves
When using 45-degree arc track segments, you can create an easement by placing two smaller radius curves inside of two larger ones. This is the easiest way to build an easement with a segmented model railroad track. The diagram at the left shows how the four different radii curve segments used in the semi-circle diagram above can be used to make three easements with tracks that are still parallel.Continue to 5 of 6 below.
05 of 06
Better Easements With Smaller Arcs
Depending on the track's manufacturer and gauge, curved segments may be available in 30, 22.5, or 15-degree arcs. The diagram at the left shows easements made by combining three different radii curves. This can be done with 30-degree arc curves or, if 30-degree segments aren't available, with 15-degree arcs as shown. While these easements are still parallel, they are wider than those above.
06 of 06
Flex Track Easements
As I've already said, the only way to make a geometrically correct easement using model railroad track is with flex track. To do this properly you need to trace a line using a large architectural parabolic curve on your layout board and lay your track along its path. If you don't have a large architectural curve template, Model Railroader Magazine offers templates for making easements with flex track as free downloads on their website.