Zipper merge starts on Johnson County project Tuesday

Tuesday is the day that drivers in Johnson County will begin using a different method for merging in a construction zone: a “zipper merge.”

The zipper merge will make its Kansas debut on a repair project for the U.S. 69 bridge over 119th Street in Johnson County.

Rather than merging early as soon as it’s safe, drivers will be asked to wait to merge as long as possible after reaching the construction zone.

Under this method, drivers are expected to remain in the soon-to-close lane until the merge point. They then take turns merging into the single lane. The zipper merge is safer when traffic is heavy and slow.

On Tuesday, crews first will set the traffic control on the project. Later in the day, the northbound lanes of U.S. 69 will be reduced to one lane and drivers will begin using the zipper merge in the construction zone.

Traffic will be limited to 55 mph and an 11-foot lane width restriction will be in place.

Drivers should expect major delays during peak commute times and are encouraged to allow extra time or seek alternative routes.

Transportation officials started looking at the method a year ago but didn’t have time to implement it until this year.

The use of the merging method is a pilot project to see how drivers respond to it. This will be the only project where it’s being used in the foreseeable future.

The method uses extra signs and other traffic control equipment, including radar, installed in June. The radar will detect traffic speeds to help monitor traffic congestion. The variable message signs will tell drivers which lane to use and when to merge.

The advantage of the zipper merge is that it allows traffic to use the closing lane up to the merge point. Traffic doesn’t back up as far and both lanes travel at the same speed, reducing road rage significantly because everyone is equally disadvantaged.

When traffic is light and free-moving, drivers can merge as space allows and not use a zipper merge. The construction zone will have special signs alerting drivers when the zipper merge is in effect.

The department has a web page that explains the zipper merge.

The $565,385 bridge project is expected to be completed by late November.

This story was originally published June 30, 2016 at 11:10 AM with the headline "Zipper merge starts on Johnson County project Tuesday."