WENATCHEE — They call it the “zipper.” And zip it does, impressively opening and closing a traffic lane on the Sen. George Sellar Bridge each night by moving a 1,250-foot-long string of heavy concrete barricades as if they were made of foam.

Kuney Construction — the Spokane contractor that is widening traffic lanes and making structural repairs on the bridge for the Washington State Department of Transportation — uses the equipment to open and close a traffic lane each night its employees are working. The machine is owned by the DOT.

The zipper is more correctly known as a Quickchange Mobile Barrier and transport vehicle, or QMB, for short. The linked concrete barriers are part of the mobile barrier system and specially designed to be moved by the zipper, said Kevin Waligorski, DOT project engineer.

The barrier system offers construction crews more room to work on the bridge at night when traffic is light. The bridge’s four lanes are open from 6 a.m. to 7 p.m. Crews do most of their work between 7 p.m. and 6 a.m. Monday through Thursday.

The zipper makes its appearance after 7 p.m. from the east side of the bridge, where it is kept. The driver of the strange-looking vehicle pulls up to the end of the barricade and the machine straddles the first of the long line of solid concrete sections. Each section in the barrier is about 3 feet tall and 3.25 feet long and weighs close to 3,000 pounds. The zipper lifts the section by its T-shaped top and rolls it into its conveyor mechanism. The conveyor shifts the concrete section from one side to the other of its wide body using rollers. Each of the concrete sections are attached to the next with steel pins that allow it to flex. The barricade is fed through the mover and shifted 10 or 12 feet as the machine is driven over it at about 5 mph. It takes only a couple of minutes to move the entire 1,250-foot barrier over and close off or open up a lane.

“We want the workers to be able to do their work safely. But we have between 55,000 and 60,000 vehicles a day going over that bridge. It’s important that we have the bridge fully functional as much of the day as possible,” Waligorski said.

The equipment has been used often in the Seattle area, but, as far as Waligorski knows, this is the first time it has been brought to North Central Washington.

The system was brought over from Western Washington and Kuney employees were trained to use it. He said the DOT owns two of the zippers and about 12,000 feet of moveable barricade. Similar equipment is used in some metropolitan areas to alter traffic lanes for commuter rush hours, he said.

The work will continue until Christmas, or when cold and snowy weather make it difficult and dangerous to work. The DOT wants to keep all four lanes of the bridge open once snow begins to accumulate, Waligorski said. Construction will resume in March when the zipper will be used to move the barricade on the other side of the bridge while workers build a new pedestrian walkway outside the south side of the bridge structure. The entire job won’t be completed until next fall, he said.

Rick Steigmeyer: 664-7151

steigmeyer@wenatcheeworld.com