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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?

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?

I understand the principle behind it all; I'm just not sure if the average punter really notices these things. To me, it solves one problem, but potentially introduces others because our design tools have to use kludgy workarounds to achieve a result. Oh, for the control of typographical software!

Lastly, here's a comparison between the three superellipse presets (solid magenta) and a standard curve (dotted cyan). The default preset, which produced the most pleasing result in my tests, actually sits entirely inside the standard curve, but probably looks optically correct because of that.

The ellipsoid preset actually goes outside the standard curve, which results in a squarer look that's not great for transit maps. The big preset actually aligns with the standard curve at the 45-degree tangent, just with smoother transitions to get there.

What script are you using? It'd be fun to try this out on some of our map geometries to see how it feels.