This has been on HN before (it's been >1 year), but I'm reposting because I just recently learned about it and I'm fascinated by it.

I also saw this super cool physical demonstration and had to share: https://www.youtube.com/watch?v=nMrYlspifuo

Up and Atom did an episode on Braess's paradox https://www.youtube.com/watch?v=cALezV_Fwi0