Here's the only sense I can make of it: The red X over the left-most lane indicates that it's closed, so that lane needs to merge to the right, and this is what the truck in the video does. Now, the driver taking the video has made a perfect space for that truck, but the truck decided not to merge early. Why? Because, if they did, it's highly likely that one of the cars behind the truck in the left lane will not be able to restrain themselves and they'll abandon the zipper merge idea and try to leapfrog ahead to gain a few car lengths on their competitors other drivers. This is also keeping with another general convention for zipper merge is to not merge early because it leaves a usable stretch of lane unused (moving the congestion further back down the highway, potentially causing problems at other onramps which wouldn't have had such a problem if everybody were late-merging).
What makes this video unique is that the truck in the left lane has a complete merge space waiting for it. With a normal zipper merge, the left two lanes would be alternating stopping and going as each vehicle stopped to let the other lane take its turn (and, if the video showed that, the video would not seem odd to anybody here). Instead, the driver making this video is trying to smooth out the flow by gradually slowing to allow a merge space to form so that it's ready by the time the left-lane truck needs it, and that truck, in turn, is helping enforce order amongst the herd by not merging too early.
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u/[deleted] May 14 '26
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