A dynamic late merge (zipper merge) allows drivers to use all lanes of traffic until the merge area is reached. At this point, motorists should merge in an alternating fashion, like a zipper.
What are the benefits of a zipper merge?
When a vehicle slows down to merge early in heavy traffic situations, it puts all drivers in danger, slowing traffic down too quickly, leading to unexpected crashes or angry motorists. These dangers are decreased using the zipper merge. Traffic backups can be reduced as much as 40%.
How does it work?
When you see a Lane Closed Ahead sign, continue to drive in your lane until you are prompted to merge. When you reach this point, take alternating turns with other drivers to merge into the single lane of traffic.
The only way this can be effective is if we are all aware of the zipper merge and follow its rules.
When driving in this situation, slow down and alternate while merging. The zipper merge allows for everyone to move at the same rate, minimizing delays for all. When traffic is heavy and slow, it is much safer for motorists to remain in their current lane until the point where traffic can orderly take turns merging.
When is the zipper merge not applicable?
When traffic is moving at highway speeds and there are no backups, it makes sense to move sooner to the lane that will remain open through construction. The bottom line is to merge when it is safe to do so.