Too late, already happened, it's called squirrels. cf. CCC NOC logo: https://events.ccc.de/camp/2019/wiki/Static:Network — it's an in-joke about rodents chewing through the (air/tree-strung) uplink fibre multiple times at the 2015 event.
That campground info hooks back into the old joke I was referencing.
What's the most important piece of camping gear you can take with you?
A meter or so of fiber optical cable. So that if you get lost of injured you can bury it and wait for the backhoe to show up and dig through it, then get a ride back to civilisation with the operator.
Yes, poles are standard practice in a lot of places, but not generally for backbone links. There's only a few of those and it makes sense to get the extra protection from burying them.
Also, installing general telco fibre next to railway lines is standard practice. Makes all the bureaucracy so much easier if you can just use the existing railway right-of-way. Not that the DPRK would care much about right-of-way ;D
As for utility boxes along the track, it could be something railway-related, for example, some railway control or monitoring equipment.