Could you give me a source for this?

Preferably a Finnish one. Not by language (although am Finnish so not an issue) but like a reliable source in Finland documenting that’s what they’re for?

I know we do have lots of infra designed “in case of Russian attack”, mainly the direction of roads on the eastern border, but I’d like to read up on this blowing bridges shit.

I’m not sure if this is something you’ll find an official source for as FDF isn’t known for openly sharing information regarding national defence.

However, you can find plenty of discussion for it online and for example on this video it’s mentioned around the 1:25 mark.

Yeah but I don’t see those hooks as being related. You don’t really need hooks like that to blow a bridge and that’s a small underpass of a regular road. You could cave that with a few sticks of TNT. And drilling them into the wall is much more efficient than hanging them off the wall.

I just suspect these hooks are just remnants of building it, and not for any specific purpose. Don’t really care if I’m wrong but I won’t be dissuaded unless someone actually proves it properly.