> #7 In many states (e.g. [1]) if two lanes are merging you're expected to merge at the last possible point. This allows more cars to fit on the road to reduce congestion, and it reduces sudden stops.
Maintaining smooth merging is far more important than where the merging happens.
The page you linked even says "It is legal to wait to merge until the lane closure devices (cones or barrels) start, but we recommend merging sooner than that to give more time to find a gap, complete the merge, and avoid getting in a pinch when the devices make the closed lane too narrow. Merging sooner also avoids the risk of hitting a closure device or ending up inside the work zone."
It recommends zippering, but nowhere in there does it recommend waiting for "the last possible point".
Someone that has it in their head that zippering is best and zippering needs to be done at the end is likely to cause more harm than good, even if they're working off the purest intentions. Keeping both lanes in use is a distant second priority to making sure the merge is smooth.
By definition, zipper merge means late merge [0]. The problem is that if some cars merge too early, other cars will keep driving down the road and then merging in front of the early mergers, it ends up being disruptive in heavy traffic conditions. If everyone consistently merges at the same point in heavy traffic conditions it's more predictable, leading to better through flow.
Tell that to the site linked above, because even though they say "like a zipper" they want it to happen early.
> The problem is that if some cars merge too early, other cars will keep driving down the road and then merging in front of the early mergers, it ends up being disruptive in heavy traffic conditions. If everyone consistently merges at the same point in heavy traffic conditions it's more predictable, leading to better through flow.
I don't blame the early mergers there. If someone zooms down the empty lane then they are not attempting to zipper merge, they are bad actors.
A proper zipper, at the last moment, is slightly better than early merging. But again smoothness is the important factor. Smoothness is 90% of the solution. Do not give up smoothness for the sake of being more zipper-y. If people think you're cutting in line, you probably are cutting in line.
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Also, anywhere we want to make sure there's a zipper merge, how about we stop having a favored lane? Cut off half of each lane at the merge point.
Maintaining smooth merging is far more important than where the merging happens.
The page you linked even says "It is legal to wait to merge until the lane closure devices (cones or barrels) start, but we recommend merging sooner than that to give more time to find a gap, complete the merge, and avoid getting in a pinch when the devices make the closed lane too narrow. Merging sooner also avoids the risk of hitting a closure device or ending up inside the work zone."
It recommends zippering, but nowhere in there does it recommend waiting for "the last possible point".
Someone that has it in their head that zippering is best and zippering needs to be done at the end is likely to cause more harm than good, even if they're working off the purest intentions. Keeping both lanes in use is a distant second priority to making sure the merge is smooth.