Merge (traffic)

This method may reduce the chance for rear-end collisions by warning drivers of the closure in advance of congestion.

[2] A dynamic merge strategy involves advance notices for a variable distance from the lane closure.

For example, in the US state of Indiana, a dynamic no-passing zone is created in advance of the merge, to ensure drivers can move into the open lane before reaching the end of a queue.

[2] In the case of Interstate 77 in North Carolina, where signs directed people to use the zipper merge, the maximum length of the backup was reduced from eight miles to two.

[2] Some governments hold campaigns to promote the late merge method because irritation and aggression are common among drivers who are not educated about the benefits of the technique.

The Code does however recommend merging in turn if it is safe and if vehicles are travelling at a very low speed (Rule 134).