Furrens wot has been in RoI might enter NI thinking new country = change of side? Or it's put up against the remote possibility of RoI deciding to drive on the right? Or just automatically it goes up on/near all border crossings?
I like the way the grass starts growing in the middle of the road right on the border. I'm not sure which side of the border that grass is on, but it's clearly lost its passport!
They aren't at many border crossings, but there a few in this part of the world (reputedly the inspiration for Spike Milligan's "Puckoon") on the north shore of Lough Erne between Belleek and Pettigo, which was cut off by road from the rest of Northern Ireland until after WWII . The signs are in the RoI which is here north of the border.
There is a good fishing lough just to the south, which accounts for the difference in the state of the roads. Carry on for a couple of miles until you get to a fully paved road again, and you will find this relic of pre-EU days: