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INDIANAPOLIS — Get ready for a new way to merge.

A diagram that describes the process of zipper merging.

(Photo provided by INDOT.)

The Indiana Department of Transportation will be transitioning this construction season from merging early in construction zones to merging late. It’s called zipper merging.

Zipper merges are designed to keep traffic moving by allowing drivers to use both lanes until reaching the merge point.

As drivers see “lane closed ahead signs,” they should stay in their current lane up until the designated merge point. Then, drivers should take turns moving into the open lane.

INDOT says this is much safer than merging early, which causes congestion and more significant changes in speed.

When a zipper merge is in place, be respectful of other drivers who wait to merge until just before the lane ends — they’re doing it right, says INDOT.


INDOT says there are many benefits to the zipper merge:

  • Reduces speed differences between two lanes
  • Reduces queue length by up to 40 percent
  • Reduces congestion and keeps traffic moving smoothly
  • Creates a sense of fairness and equity that all lanes are moving at the same rate
  • Brings order to the merging process

INDOT says you won’t have to wonder if there’s going to be a zipper merge — there will be signage notifying you if one is being used.