Unfortunately, you cannot yet use Junction Boxes on Roundabouts, so that option is not available. Instead, you’ll need to employ one of these ugly map hacks:
move the A1 exit to be before the entrance from A1231, then it cannot be given as a route. It can be an “inside” exit, that then goes out of the roundabout at it’s current location so it still looks right on the client. The down side is that the exit count from A1231 will start with the next exit being 1st, which may or may not be desirable.
or, make both the entrance and exits have 90 degree angles, and a gap less than 15 metres so that it looks like a U turn on a H junction. Waze will then avoid routing this way. [example]
Thanks for the feedback, I have not used the Junction boxes on the map yet (only read about the functionality in the wiki) and I thought they could have worked theoretically, but as is the way
Looking at it I see that the H junction may work better than exit before entrance going off the example.
I’m only L2 still (16,874 edits) so can’t make the edits.