It’s called the “Zipper Rule.”
When two lanes of traffic heading the same way encounter a construction site, one lane has to merge into the other. There’s a tendency for drivers to change lanes early but THAT creates a bottle neck when the merging point arrives according to Sergeant John Lueckenhoff of the Missouri State Highway Patrol.
“Maybe you’ve got some cars waiting and they decide ” I’m going to move into that other lane that is open,’” Sgt. Lueckenhoff says.
“Well you’ve got cars at highway speed and all of a sudden they come up in a line of stopped traffic. And that’s where we have those horrible collisions.Drivers in merging lanes are expected to use both lanes to advance to the lane reduction point and merge at that location, alternating turns.
Sgt. Lueckenhoff says the Zipper Rule has drivers take turns merging into the single lane, much like a zipper when it closes. That keeps traffic flowing continuously ….. with fewer chances of accidents.