Bridge. The 6 lanes were empty for, ii day in a row as the move able median barrier got a test run. Big yellow machines ran back and forth across the bridge all day. They are called zipper trucks. And the Golden Gate Bridge district says they will be moving the 11,500foot barrier 3 to 4 times per day. The whole process should take about an hour from beginning to end. How we manage that we look at what the backup is and we do realtime analysis, and we want to provide the configuration that provides least cumulative delay in both directions. Reporter it takes practice moving the barrier. At one point a zipper truck stalled on the middle of the bridge as they worked out issues. The bridge district had operators training throughout the day to get it perfect. Navigating that placing the barrier accurately within a half inch takes some practice. We have all of our crews going through that. Reporter some changes drivers should be aware of. First and for most the inside lanes will be half a fo