MDOT convinced “zipper merge” will reduce traffic delays

Posted at 12:40 PM, Aug 28, 2015
and last updated 2015-08-28 12:40:19-04

GRAND RAPIDS, Mich. -- Drivers enduring repeated weekend traffic jams on I-196 in Kent County have been the students and the Michigan Department of Transportation has been the teacher. The subject: the so-called zipper merge.

Road repairs and bridge work have led to regular weekend lane closures on I-196 between Grand Rapids and Grandville this construction season. The backups have been long, but there’s evidence in FOX 17 videos that drivers are picking up on MDOT’s efforts to use the zipper merge.

Using the zipper merge process, drivers use all lanes approaching a lane closure and only merge at the point a lane closure occurs. “It doubles the capacity,” says MDOT Grand Region representative John Richard. “It works well when there's high volumes of traffic.”

MDOT sign Merge One Mile AheadThis is quite a change from the behavior Michigan drivers have displayed in the last few years after MDOT campaigned for use of the so-called early merge system, where drivers all converge in a single lane well in advance of a lane closure. That still holds for construction situations where traffic is light.

MDOT will ask drivers to perform the zipper merge only in certain situations, says MDOT assistant construction engineer Tanya Pawlukewicz. She has been the point person on this year’s zipper merge project.

“We definitely pick specific projects,” Pawkukewicz says, “when the closures are going to be during specific times -- normally peak hours and in specific locations, like when the volumes are increased.”

The I-196 repairs fit the bill. (Drivers will be pleased to hear that this weekend, Aug. 28-30, is the last weekend for disruptive lane closures on that stretch of highway.)

But some drivers don’t get it. Some even try to keep other drivers from passing them in an open lane by weaving and blocking, straddling the center line. Richard calls such drivers “vigilante lane straddlers.”

“When you have the vigilante lane straddler, that causes nothing but road rage and confusion. It doesn't help at all,” Richard says. “Blocking moving traffic is illegal, and if you get fined in a work zone, the fines are doubled.”

“Do not try to block traffic. It's very dangerous, and it only causes problems.”

Zipper Merge signAs for whether drivers are getting the concept, it was clear on I-196 early on they were not. After the first weekend, MDOT created and posted new signs with the image of a zipper, and changeable signs were added that first warned of the lane closure, urged drivers to use both lanes, and then, at the lane closure, told drivers to “merge now” and “take turns.”

That may have worked. Video FOX 17 recorded last weekend showed slow traffic, but drivers were using both lanes.

MDOT became convinced the zipper merge was the preferred system to use in high-traffic construction zones after trials in 2014, says Pawlukewicz. Signs explained how to execute the merge on I-96 lane closures in Lowell Township in eastern Kent County.

“We reduced delays, cut them in half,” says Richard.

Notice that Richard says delays were reduced, not eliminated. Lane closures will always cause traffic jams, he says. “Every time  you take a lane away on a major route like 96 and 196, 131, it's going to cause congestion. But, if it's used effectively, it'll be a lot less congestion.”