Local Information

Pilot project: Zipper merge for improved travel on eastbound SR 14 in Vancouver

Friday, August 23, 2019 - 09:34

Celeste Dimichina, communications, 360-905-2057

VANCOUVER – With nearly 40 percent more traffic using eastbound State Route 14 in east Vancouver over the last 20 years, traffic backups and delays are a common occurrence between the on-ramps from Interstate 205 to eastbound State Route 14

In an effort to maximize use of the roadway and reduce congestion, the Washington State Department of Transportation has installed new informational signs along the shoulders of eastbound SR 14 to encourage travelers who are in the merging lanes to zipper merge where the right lane ends when entering the highway. 

“With this zipper merge pilot project, we’re working to make the most of the existing roadway by encouraging travelers to take turns and merge late during heavily congested travel periods,” said WSDOT Traffic Engineer Rick Keniston. “While it may seem counterintuitive, we find that the early merger, who is trying to be polite and wait in the queue, is often making traffic worse than the driver who merges closer to the end of the lane. We need all travelers to be on the same page to make the zipper merge system work.”

The idea behind the zipper merge pilot program is that travelers use the full length of the merge lanes during congested periods, which results in more traffic getting through the area in less time. Studies have shown that when traveler’s zipper merge, congestion can be reduced by up to 40 percent, while reducing crashes, backups and delays. 

During free-flow traffic conditions, travelers should continue to merge as conditions allow, when they find a gap in the flow of traffic and when it is safe to do so.

Over the next year, WSDOT will continue to monitor this stretch of highway to evaluate the possibility of actively promoting zipper merging in other areas.

WSDOT is also designing a project to add lanes to this stretch of SR 14, with construction scheduled to begin in 2021. Until additional lanes can be added, travelers working together can help improve the flow of traffic along this corridor.

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