[2020] Has anyone seen this sort of weirdness with terrain blowouts?

Oof, that does not look nice. :S Definitely looks like something a broken mod could cause. If you haven't already, I suggest checking your mods against this list of known broken mods:

https://docs.google.com/spreadsheets/d/1mVFkj_7ij4FLzKs2QJaONNmb9Z-SRqUeG6xFGqEX1ew/edit#gid=0

Originally posted by big.red.us: It appears to have been Low Bridges High Dams mod.

Ah, that would explain it! Thanks for the heads up, I'll add it to the list of broken mods.

If you want a replacement, Fine Road Tool 2 can do the same and is up to date. :)

Originally posted by winobob: I get stuff like that all the time... Especially when adding roads near harbors where I've previously edited the terrain. It also happens when I put down quays in those areas as well. I don't use the Low Bridges, High Damns Mod.

Do you have any of these mods: Fine Road Tool (original, not version 2), Fine Road Anarchy (original, not version 2), Advanced Road Anarchy, Road Anarchy, Road Anarchy 2 or Sharp Junction Angles?