A Tangent and a Curve

Today I got the roadbed mounted for the tangent track that will allow the oak tree circle to serve as a return loop - a teardrop shape that allows trains to be turned and sent back the way they came. Here's a ground level view looking north across the switch. The straight leg heads north - the return leg. The curve to the right heads around the tree.

On the south side of the tree I trimmed and attached the supporting plank for the first section of the #1 Cornelia arrival track, then mounted the plastic conduit that magically reveals exactly where the bridge over to the house needs to be.





















Perhaps more importantly for smooth operation, the conduit automatically bends itself into these curves with perfect spiral easements - transitional curves between straight tracks and fixed-radius curves. These were proposed as the early as 1828 for track laying but did not become standard until locomotives began to move at speeds high enough for these spiral easements to matter.

On the tight curves in the Cornelia Yard area of the TFRR these easements will allow the trains to move more smoothly with less binding and less chance for derailments. This is especially important in the flattened "S" shaped curve at the bottom of this photo, between the two switches.




























The switch sitting by itself in the middle of the photo designates where the #2 Cornelia arrival track will peel off. Arrival #2 will serve as the "run-around track" for Cornelia yard - a parallel track that allows a locomotive to move to either end of a string of cars as needed. The #2 track will run parallel to #1, a second curve over the walkway toward the house.