Zipper Merging: Washington State’s Most Misunderstood Traffic Law

Are you sure YOU understand the law when it comes to zipper merging?

Zipper Merge Law Confusion Resides in Washington State

There seem to be a lot of drivers in Washington State who are confused about zipper merging in construction zones. In the Tri-Cities where I live, the Blue Bridge construction on US-395 has been one source of both anger and confusion from this issue. The Washington State Patrol has been on the scene enforcing the laws while trying to teach drivers the legal way to zipper merge at the same time. One side of the argument points to Washington State Law which says all merging drivers must yield to drivers already in the highway lane. "RCW 46.61.205, the driver of a vehicle that is about to enter a highway must yield the right of way to all vehicles on the highway that are approaching it," says one X user on a recent Washington State Patrol post about zipper lanes. The fact is the user is completely wrong because RCW 46.61.205 has nothing to do with merging onto a highway but the law for "Vehicle entering highway from private road or driveway."

Zipper Merging Laws Help with Washington Construction Zone Safety

The important thing to understand about zipper merging laws is that they are for areas around construction zones or areas where merging is required when one lane is ending.. WSDOT explains the legal argument in easier-to-understand language saying, "It is the merging driver's responsibility to merge safely. However, it is illegal for drivers in the open lane to actively block merging traffic, including blocking part of the merging lane to prevent perceived cutting in line." They go on to explain, "When traffic is heavier, you can wait longer before merging, and this can sometimes help with a smoother merge, as well as reducing the length of backups. It is legal to wait to merge until the lane closure devices (cones or barrels) start." They use the phrase "Merge Late, cooperate!" WSDOT says to use the zipper technique during traffic merging both in construction zones and during normal heavy traffic. You DO NOT need to zipper merge if executing a regular merge into traffic. In that case, the vehicle already in the lane has the right of way. If you are still confused about zipper merging, I posted a video from the Washington State Department of Transportation below for you to watch. You can also read House Bill 1231 which was passed in 2019.

DO NOT DO THIS While Zipper Merging

The Washington State Patrol caught a semi driving down the center of both zipper lanes holding back traffic on Saturday just before noon around the Blue Bridge construction. The Trooper quickly pulled the semi over and educated them while writing an infraction and a follow-up inspection. Washington State Patrol Trooper Chris Thorson said in the post, "I just watched this semi-truck and trailer block both lanes on purpose so no other cars could pass him in the construction zone leading up to the Blue Bridge. #NotAcceptable"