Technically, the answer to the question above is “when it has a zero radius.” In other words, a curve isn’t a curve when it’s a line – or is it?
I’ll be the first to admit that I don’t know everything (shocking, isn’t it?) And, I have plenty of friends who seem to wait for me to be wrong so they can gleefully point it out and laugh at me. So I won’t say it was a terrible shock last night when I was watching House, MD and my phone buzzed. It was one of my closest friends, Nick Zeeben, pointing out that I was wrong, wrong, wrong. You see, he had read the comments on this post of mine and noticed that I was incorrectly saying that you cannot add superelevation to an alignment with no curves. Nick schooled me and showed me that it could be done, and knowing what a hot topic this is, I wanted to share with you, Loyal Reader (nothing like a 7:30 AM reference to Stephen King, huh?) So without further ado, I’d like for you to hit the jump so that I can school you just as I was schooled last night.