I-87 and I-287 in NY. Why not just number the Westchester portion to I-487, or the NJ portion to I-695 (so what if it goes 0.11 mi into NY)?
I believe the former was an actual proposal from NY at one point. The latter would have worked too, since I-695 technically didn't exist in NY until 2008, according to FHWA (it was signed from 1986, but was technically a spur of I-295).
I would say that having two routes end in an overlap is the very OPPOSITE of cleaner. IMO I-69 should be truncated to end at I-94. Having unnecessary concurrencies makes for a messy system.
How is it messy? You follow one number from point A to B. Adding in an extra decision increases driver workload, which is precisely the opposite of what you'd want.
Guidance design is based on what makes sense while driving at speed, not what looks cleaner on a map.
Yeah, I'm thinking from the map. In any case, I've never had trouble with ideas like "take I-69 to I-94, then take I-94 east to Canada". Who are all these people who can't navigate from point A to point B unless the entire route has the same number, and when did they get so much power that they could influence the designations of I-69, I-11, and lobby for stuff like Continental One?
There are a few NY state routes that have odd routings or seem to be a collection of smaller routes strung together through overlaps (NY 812 comes to mind); I've always been asking "who thought this was a logical routing?". Having multiple numbers to refer to a section of road strikes me as redundant, and I'm of the opinion that overlaps should be minimized (though sometimes they're necessary).