I use a very similar approach in simulating curve easements in Fastrack as what ADCX Rob does with tubular track. I have parallel main lines on a 6" center. The difference in size is shown in my diagram. Two simple curves are shown overlaying two of my simulated eased curves. The difference in size is shown by the blue box which is about 2½" high and 7½" long.
The full ovals look like the following illustration where the upper ovals are simulated eased curves and the lower ovals are constant curves of O48 and O60. The lower ovals are 4½" narrower and there are 15½" more straight track.
The difference in operation and appearance is beautiful.
