You were right, and there IS a right answer.
Your reasoning is partially correct, too, but I think there's a more meta reason it works. As long as people try to choose their own individual merge points, there will
always be differences of opinion -- that's just how opinions work, after all. But if the DOT construction signage directs traffic to do something specific, then all those individual -- and conflicting -- opinions don't matter anymore, and everyone implicitly agrees to what the DOT (who serves as a neutral arbitrating third party) says to do.
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To apply this to your poll options:
- "ASAP" is unclear, and it's different for everyone. Some people would move over when they eventually see the flashing arrows, and some will move at the "Lane Closes 5 Miles Ahead" sign. You'll never see a consensus.
- "merge point". There's just one merge point, and that's where the lane closes. That's where nobody can choose to go straight anymore. Pretty impossible to say otherwise, so I'd say that this is most likely to achieve a consensus. (and if they put up a big sign that says "MERGE HERE" like in the video below, then there's no doubt about where it is, right?)
- "... as long as it is safe and orderly." Different people have different ideas of how safely they can move into the other lane. Some try to go ahead of the car next to them (easier to see), some try to go behind instead (more polite). You won't see a consensus here, either.
See what I mean? It's not about removal of choice, it's about removal of
conflicting choices. Less conflict = more cooperation = less stress.
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Hopefully I'm not the only one to post this vid. Same stretch of road, SAME construction project, but different instructions being given to the drivers on different days. The "zipper method" works smoother, and more safely, than letting everyone do their own thing: