HENDERSON, Ky. (WEHT) — The Indiana Department of Transportation (INDOT) is reminding motorists of the zipper merge, a way for drivers to keep traffic moving when a lane is closed. This method is more relevant than ever with the recent lane closures along the Twin Bridges between Henderson and Evansville.

How does it work?

Zipper merges are used when a lane is closed ahead, typically due to road construction or maintenance work. Zipper merges are designed to keep traffic moving by allowing drivers to use both lanes until reaching the merge point.

According to INDOT, as drivers see “lane closed ahead” signs, they should stay in their current lane up to the merge point. Then drivers should take turns moving into the open lane. Officials say this practice is much safer than merging early, which can cause congestion and 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 officials.

Zipper Merge vs. Early Merge

INDOT says most drivers often merge at the first sight of a “lane closed ahead” sign, however many slow too quickly, which can lead to unexpected lane switches, serious crashes and road rage.

Zipper merges provide several benefits to the traveling public. Risks decrease when motorists use both lanes until reaching the defined merge area and then alternate or take turns moving to the open lane in a zipper-like fashion.


  • Reduces speed differences between two lanes
  • Reduces queue length by up to 40%
  • 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

When shouldn’t I use a Zipper Merge?

Not all work zones are good for a zipper merge. Road officials say signage will in place if a zipper merge is present. In situations where traffic is flowing at highway speeds with no or minimal back-ups, drivers should merge early to the open lane when it is safe to do so.

(Courtesy: INDOT)