Just a little note from a MoW Trackman~ the "curve" on railroads are composed of three essential elements: first is, of course, the straight or Tangent track. This leads into a transition called a spiral, the second component. Which in turn leads into the curve itself. Then reverses the order going out of the "curve". The second component you are calling an "easement", which has a different meaning all together in modern railroading.