Thanks for those, I may get to them at some point 😊

Even a short distance NW of this edit there's a long section of the Cavan Road which should just be a single carriageway, with traffic islands mapped as nodes. The approach I take is as documented on the OSM wiki (https://wiki.openstreetmap.org/wiki/Dual_carriageway) - if there is no physical barrier separating the carriageways, it's not a dual carriageway and should be mapped as a single way. As a result the Cavan Road has driveways linked to only one side of the road, but you can guarantee the road design is not meant to be left-in left-out only for those access ways. There are occasional exceptions to what's in the wiki, but roads like these are pretty clear cut (see also examples on the wiki page).

It does take some unpicking of relations though (bus routes and the like), so needs some care. I also check which way is the oldest of the two, to retain as much edit history as possible. Give it a try some time – or otherwise I may get round to it.