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I'm not sure I'm getting the current hype for using superelliptical curves or "smooth corners" in transit map design. They seem like an awful lot of work for an incredibly small improvement that most average people wouldn't even notice to me. Interested to hear the thoughts of other on this.

I'm currently running my experiments in Illustrator with a script that approximates smooth curves (because Illustrator can't make them natively) and I am not convinced they're an improvement. Yes, the curves may be smoother to the eye, but getting parallel paths to look good is very problematic.

Here's some samples. In the top row, I applied three presets in the script to the curve: you can see where the paths now overlap or leave a gap between them. UGLY. In the bottom row, I applied the script to the middle path, and then offset the other two paths from it. Better but cheating?

And here's a version with a bit of white space between the parallel paths – the top row introduces all sorts of "wobbliness" because the gaps are not consistent. The offset bottom row looks better overall to my eye, but enough to justify the extra work involved? I'm not sure.

In type design, someone described it as driving around a 90° corner; you don’t suddenly find the correct steering angle and then suddenly straighten up at the end. For me the bottom row no. 2 is best since it doesn‘t involve any extra control points on 45, and the bezier handles are symmetrical.

Whether that is worth it is of course an economic judgment call, even if it does look a little more natural and a less bumpy ride round the corner. The principle applies to all angles btw, not just right angles :) I like your willingness to investigate. Have you come across Tunni lines in type?

And yes, I know it works at all angles: the pros and cons are just most visually obvious at a 90-degree angle for the purpose of experimentation.