What is a zipper merge?
Zipper merges are used when a lane is closed ahead 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.
How does a zipper merge work?
Zipper merges work exactly as they sound – like a zipper!
As drivers see “lane closed ahead” signs, they should stay in their current lane up to the designated merge point. Then drivers should take turns moving into the open lane. This practice 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!
Zipper Merge vs. Early Merge
Most drivers tend to 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.
What are the benefits of a 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
When should zipper merges not be used?
In situations where traffic is flowing at highway speeds with no or minimal back-ups, drivers should merge early to the open lane. Not all work zones are conducive to use of a zipper merge. Signage will be present if a zipper merge is present, and motorists should continue to merge when it is safe to do so.
Visit the INDOT website to learn more: bit.ly/INDOTZipperMerge.
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About the Indiana Hands-Free Law
In 2019, Indiana Criminal Justice Institute reported that distracted driving from mobile devices was a factor in at least 1,263 crashes and three fatal crashes. To make Hoosier roads safer, Governor Eric J. Holcomb signed the Indiana Hands-Free law to reduce distracted driving across the state. Beginning July 1, 2020, drivers are prohibited from holding a mobile device, except in emergencies, while their vehicles are moving. For more information on the new law visit www.HandsFreeIndiana.com. Hands-Free Indiana is a partnership between the Indiana Department of Transportation, Indiana State Police, Indiana Criminal Justice Institute, Indiana Bureau of Motor Vehicles, Indiana Constructors Inc., Indiana Motor Truck Association and ACEC Indiana.
About the Indiana Department of Transportation
Over the past 100 years, INDOT has transformed the state of Indiana into the Crossroads of America we know today. With six district offices and 3,500 employees, the agency is responsible for constructing and maintaining more than 29,000 lane miles of highways, more than 5,700 bridges, and supporting 4,500 rail miles and 117 airports across the state. Indiana once again ranked #1 in the U.S. for infrastructure in CNBC’s 2019 “America’s Top States for Business” ranking. Learn more about INDOT at in.gov/indot.
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