An Arizona Department of Transportation project in the West Valley this
weekend will employ whatís known as a zipper merge to get traffic into
one lane in a way that reduces delays.
The merge will be used during daytime hours on westbound Interstate 10
between Watson Road and State Route 85 in Buckeye, where one of the two
lanes will be closed from 10 p.m. Friday, Oct. 7, until 5 a.m. Monday,
Oct. 10. The zipper merge will be in place between 6 a.m. and 8 p.m.,
when traffic is heavier. At night, drivers should merge earlier when it
is convenient and safe.
This work also will close on- and off-ramps at Miller Road from 9 p.m.
Friday, Oct. 7, until 9 p.m. Saturday, Oct. 8, and westbound I-10
connecting ramps to SR 85 from 9 p.m. Saturday, Oct. 8, until 5 a.m.
Monday, Oct. 10.
The zipper merge works best for construction projects with heavier
traffic and slower speeds. Digital message boards instruct drivers to
remain in both lanes until right before the lane restriction. Then
vehicles take turns getting into the open lane, much like a zipper
For the zipper merge to be as effective as possible, drivers approaching
the work zone need to cooperate and let go of the notion that they need
to merge early. In the interest of safety and efficiency, drivers also
must resist the urge to straddle both lanes to keep others from getting
The payoff: A zipper merge can reduce the length of a traffic backup by
up to 40 percent, according to the Federal Highway Administration, while
providing more predictable driver behavior. Keeping traffic in both
lanes longer enhances safety by reducing the speed differential between
This will be ADOTís second use of the zipper merge, which was also
employed earlier this year at an I-10 bridge project east of Tucson
(shown in the video above). ADOT will evaluate the results to see if it
should be used for future projects.