A little help would be appreciated...

[CN2117]

The easement is an area where the radius of the curve increases toward the straight part.

As an example, consider sectional track, take an 18" radius curve attached to a straight piece; there is no easement, you go directly from 18" radius to straight.
With an easement, say using flex track, you gradually go from the 18" radius curve to straight with larger radius.

There's a picture here that helps explain it.

http://en.wikipedia.org/wiki/Track_transition_curve

For an S curve, you don't want to go directly from say 18" right to 18" left curves, you want an easement and some straight track in between.

 

[wombat457]

Got it, thanks guys for the explanation. Ironically, and without knowing it, I have done just that with my layout - dumb luck on my part

 

[CN2117]

When you use flex track, it sort of naturally 'wants' to do easements, so it definitely makes it simpler.

 

[wombat457]

That was a nice way of saying that the track is "smarter" than the "user". No argument here!