The problem is that those instructions (wait to merge, then take turns) don't produce a zipper merge, they produce a "stop and start take turns" merge - the lef

The problem is that those instructions (wait to merge, then take turns) don't produce a zipper merge, they produce a "stop and start take turns" merge - the left-hand antipattern on http://trafficwaves.org/seatraf.html http://trafficwaves.org/seatraf.html They need the additional "keep lots of space ahead of you to allow cars to move in at traffic speed". Given a stop-and-go merge, I think the best you can do is keep that left lane from forcing stop-and-go merging. if you can get a gap in the merging lane, the target lane can begin flowing more freely, thus opening space for the merging lane.