I just want to emphasize that there are (at least) two separate but related issues here:

1)  Whether the "before" or "after" style is preferred or more correct,
2) What a routing algorithm (potentially yet-to-be-coded or now-actually coded) does with either or both.

Regarding 1), it appears that we have proponents for both styles. In OSM, I submit "that's just gonna happen." While consensus is a beautiful thing, it is not always perfectly achievable. I don't believe it (entirely) reasonable to, say, have a bot go through thousands of intersections and "make them" one flavor or another, simply to make a routing algorithm more happy or easier/faster to complete. Maybe a case could be made for that, but I'd like to hear it. (I think of it as a BIG maybe).

Regarding 2), be smart about (algorithmically handle) both flavors of intersections. Or even more. This is a "tip of the iceberg" problem that likely requires more research and a classification into more than simply two flavors of intersections. I think it possible that given the universe of possibilities, there are smart and clever ways to apply a routing algorithm: this is just geometry and computer science after all (points, vertices, and an executive that rides along the geometry which probes around, backs out, and yields results). Research the entirety of the problem domain, invest (substantially, if necessary) in the algorithm to handle most/all cases, and all can be well.

While it is fine to discuss "better methods" (note that is plural) of creating complex intersection geometry, I find it stifling to do so in the context of "for a particular routing algorithm." That leans heavily towards "coding for the routing algorithm," and I think we've learned that such coding make the underlying data not all they can be (i.e. well-formed and as correct as we are able to observe and enter them).

I seem to be echoing what Minh said near the end of his reply: "handle both." (or more).

Good discussion.

SteveA
California

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