IconoclastThis bridge in Finland has hooks to hang explosives from in case it needs to be collapsed to stop Russian advance
Plenty of bridges built in Sweden during the cold war has the openings in the foundation for the same purpose.
RobotToasterThat sounds a lot more efficient. Just hanging the explosives isn’t going to direct the energy very well.
Maybe that’s the point? You need to be able to blow the bridge, but you don’t want some asshole to be able to make some homemade explosive to blow it just because they feel like it