Does this work?

[BlackRockJL]

Does this still work with a current macOS and how can I run the application? swift main.swift seems not to work. :)

[niklaswa]

Yes, it should still work. You have to clone it in Xcode and run it from there.

I also just build a signed & notarized version, if you really want to run it (even without Xcode):
TrainStatusInfo.zip

Btw, there is a similar, more refined app in the app store by another developer which has even more features: https://apps.apple.com/de/app/ice-buddy-for-your-menu-bar/id1595947689