On the prototype where there are double tracks rounding a curve, is the entire roadbed superelevated as a unit or is the roadbed level and the tracks individually superelevated? Or is it done both ways?
george
I’ve seen both, though you usually only see the entire roadbed superelevated on forgien railways.
I have never seen the whole road bed superelevated on the New Haven, especially in 4 track territory. I use the flat roadbed (Homosote over 3/4 inch plywood) which is easy to keep level in all directions. I begin the superelevation on the tangent about a foot or more before the beginning of the spiral easement. This is prototypical according to what I have read on this subject. The curved track is then superelevated the same amount throughout the curve. At the end of the curve is a corresponding reduction to level track. I put a tapered “shim” under the outside rail which is made from a length of wood sliced from 0 to 1/8th inch on the table saw. I then rip that into about 1/8th inch wide strips. I do the same for the level shims on the curve. If they won’t bend I cut them into short lengths. It is a lot of work, but well woth it seeing a train bend into that curve like the real ones do. For 30" and up radius 1/8th is about the maximum to keep the cars from falling inward. Smaller radii calls for reducing that amount down to about 1/16th or thereabouts.
The reason that I asked this question is that I was contemplating having a passing siding merge with the main on a curve. This means that the railheads of the two tracks and the connecting switch must all lie in the same plane and thus the entire roadbed would have to be tilted.
gh
The ideal would be to transition to level tracks at the frog. As far as your superelevation goes, below 36" radius it would be so isignificant as to not be worth doing. I would even consider not doing it below 48" radius. Remember two things: Model rairoad curves are much tighter than the prototype. A 10 degree railroad curve is tight and might require a speed restriction, and it = 88"radius in HO! Second, Railroads use superelevation sparingly to counter forces at higher speed, in the neighborhood of 3" to 6" , again, practically negligible in HO. Assuming you will use easements on your curves, go a maximum of 1/16" (1/32" to 3/64" would be better) at the outside edge of the ties through the radiused part of the curve, tapering off evenly through the easement to “0” at the tangent point of the easement. Happy railroading! jc5729 Port Townsend, WA
On a club I once belonged to, there was one turnout from the outside of a slightly superelevated curve. The straight leg of the turnout was raised so that the entire assembly was at the superelevation angle. Then the superelevated, but straight, track into the industrial area was returned rather too abruptly to level. This caused considerable grief for equipment which had insufficient play in the trucks, but it did force operators to switch into that siding at prototypical speeds!