Hardly boring is right--this is what I do. I wish that I (we at my office) were closer to western Oregon (we're in Spokane). We'd love to take a look. If you could supply the original track alignment--especially the spiral type and length, it's possible to work up a "throw sheet" to see if there are or were any kinks involved, but it really does sound like a gauge problem, as you mentioned. I don't see a problem with the superelevation rate of change at that speed. Photos of the track involved would also help. To answer your original question, railroad curves are designed with the same chord definition formulas today as they were then. There are some spiral types that might not be supported anymore with most available computer software. I'm not certain what the Jackson does with certain spiral types, but the curves should be being figured exactly the same by it. I have used 4 or 5 spiral types during my career. You can lay them out over the top of each other and see that there is really a difference--nothing that is going to yank the earth from its axis and go spinning into the sun, but it is an interesting study (but yes, probably pretty boring to a lot of folks). If you are interested, drop me a note at rogerh@cet.com.