I have to agree with bazgrant as well.
I think the "problem of Dubai" is not caused initially by the split roads.
But as i also read in another post of nbezuidenhout, there are a lot of crazy segments, overlaying other seggments, sometime 3 or 4. Sometimes half overlap, and therefore it looks like one road, but there are 2 or 3 and not connected.
I didn;t run into that in Abu Dhabi, but I do in Dubai. And it's a nasty job to fix those.
The issue of unsplitting roads is that it's causing a lot of red arrows on the map, if you do it right. Because a lot of roads, are connected only on 1 side of the road, such as parallel parking roads, and local acces roads. It will be a hell of a job to set all these right. And if you have bad luck, and a level 1 editor finds the SHIFT-Z option, he'll set them all to green turns and ruins the map.
About the spaghetti crossings of 2-by-2 (primary) intersections: we should keep it simple, and functional, and not draw all the possible traffic motions. If it works with the right instructions, you just get a simple square, with u turns possible drawn outside it. Sometime the shortcut for taking a right (if its a big cut-off of the corner) and that should do it!