Even more curious.

There doesn't seem to be a sign on the south bound approach on the A5 from Bangor, and the sign on the north bound approach doesn't specify which direction on the A55.

If there are such signs on all the approaches, this is evidence that they are not of themselves prohibition signs. Otherwise it would be illegal to ride through the roundabout S-N on the A5. You have not marked a ban from any of the signs, nor are there any signs at the places you have mapped a ban.

For a ban to be legal there must be a traffic regulation order. So I can only conclude there isn't actually a ban.
