Zipper Merge

Within a construction zone, there are times when two lanes of traffic must be merged into one lane.
When traffic is light, this isn’t a big deal. A simple lane change keeps the flow of traffic moving at normal speeds… and an early merge is the most effective course of action.
However, as traffic volumes increase, most drivers believe that the sooner they get out of a blocked lane the better.
But in moderate to heavy traffic, that quite often can create backups as early mergers believe other drivers are bypassing the line and cutting in front of them right before the lane ends.
When traffic is heavy, the zipper merge or late merge, is the most effective and safest way to get through a work zone.
A zipper merge is when drivers use both lanes up until they reach the closure, and then alternate into the open lane. This late merge maximizes road space and can reduce congestion significantly…
Smart work zone technology traffic sensors will detect when vehicles begin to slow down as they approach the work zone. Message boards close to the work zone will instruct drivers to use both lanes as they approach the merge point and then to take turns at the point that the number of lanes reduces.
Further away from the work zone, message boards will alert traffic of slowed or stopped traffic conditions ahead. These messages will give specific distances to the slowed or stopped traffic.
Again, when traffic is really backed up the best plan is not to merge early. Drive in both lanes until you get to that merge point, and then take turns moving into the through lane.
You know… like teeth on a zipper.

[@usmantariq7997]

The problem is, even if you wait till the end, some drivers just won't let you in. They will try to block you and then road rage with you if you get stuck behind them.

[@Nikola16789]

The problem is, zipper merge is not more efficient.

[@wjrneo2]

@@Nikola16789 It is, significantly so. It reduces the amount of space each driver must give up to another car to make room for a merging car. If you are in the non-closing lane, you only have to speed up or slow down a very little, 1 car length, to allow another vehicle to merge with your lane. But, if you force a car that's merging to have to speed up or slow down significantly to skip several cars it has a massive traffic slinking effect on the closing lane, which then impacts the non-closing lane as the cars merging into the lane are doing so at a significant speed difference. Giving up 10ft, or accelerating 10ft to create room for a car to merge in front, or behind you is the best way to do it.

[@nispelsm]

@@wjrneo2 But this is precisely why zipper merges don't work. No one is willing to give up the space in front of them, even when legally required to do so. Sometimes it's because they think others are "cutting in line", but more often it's just plain ego and stubbornness at play. They can't let someone in front of them because it means they "lost" some imaginary contest.

[@Nikola16789]

@@wjrneo2 That's just a perceived gain. In reality, limiting factor is capacity of narrowed section which is always maximized.

[@wjrneo2]

@@nispelsm They work more often than not, and just because poorly educated drivers don't do it, doesn't meant its not worth teaching. They never taught us to zipper merge in drivers ed in the 90's, not a lick of that. And it's something that should be taught, it should be. Honestly, if you need to merge you should find the easiest opening that doesn't cause anyone else to speed up or slow down and slot into it. Using the excuse, "I don't do it because nobody else will" is a self fulfilling prophecy.

[@nispelsm]

"Take turns" they say ... LMFAO. There is no one gonna follow that rule. You can't even convince drivers to leave a space in front of them at speed, let alone while in a slow construction zone.

[@elijaha773]

Informational videos and using sign boards is good, but TDOT should also work with the Department of Education to reintroduce traffic safety classes (including driving, cycling, and walking) to schools to create a well-educated public.

[@tangentfox4677]

Imagine if people knew this.

[@tangentfox4677]

Instead they get mad or try to block me.

[@PaintballBoomer]

The other problem is people who shoot out of the open lane into the closed lane to move up 5 cars and then "zipper". I full support the zipper, but North American drivers are too entitled to actually do this.

[@sergoogle5061]

This doesn't consider real time drivers and the human condition to be like "the f you are" to other people. Good presentation but limp on the overall data