The SHAY MOUNTAIN RAILROAD and GENERIC PACIFIC (A Layout Plan in Words) Continued
Whereas the Generic Pacific would be a continuous (“roundy-round”) loop that represents a through long distance mainline railroad with generous curve and grade standards to accommodate mainline equipment, the Shay Mountain railroad would be a mountainside climbing line, probably point-to-point (or point to reverse loop?) with short cars, small tough locomotives, sharp curves, steep grades and perhaps a deliberate obstacle or two. The model might represent cheap make-due construction, which would actually mean long hours of scratchbuilding with crude materials, whereas the Generic Pacific would represent expensive professional class-one civil engineering, which would be modeled by inexpensive off-the-shelf plastic models of steel bridges, etc.
Curves: While the Generic Pacific needs generous curves, the Shay Mountain line can get away with sharper 18” radius curves, and it fact it NEEDS sharper curves to get the feel of the short line railroad. (You might “get away” with 15” radius, but that might require a fair amount of tinkering, adjusting of models, testing, etc. 18” would probably be “safe”.)
This means that an end-of-the-layout turnback curve of the Shay Mtn line can fit INSIDE the turnback curve of the GP mainline. (A Shay Mtn 18” radius, 36” diameter to track center lines*, inside the mainline curve of 22” radius back, 28” radius front, diameter 50” (track
centers).
*NOTE: Remember that the “nominal” radius of a track curve is the radius to the imaginary line down the center line of the track, as if you drew its path with a single line. The width of the track takes up space both inside and outside that line.
We said earlier that the Generic Pacific loop might have a reverse loop at one end. The smaller radius Shay Mtn curve would fit inside the end curve but there would be a problem if the two lines were at the same or almost the same elevation. The S