This Huge Urban Zipper Machine Can Reverse Traffic on the Golden Gate Bridge

While you were busy holding the tip of the Golden Gate Bridge up with your fingers so your friend could snap a picture of you, many San Franciscans were crossing that iconic orange span to get to and from work. This 1.7-mile commute is one of the most scenic, but also can be a harrowing experience. Since 1970, there have been 128 head-on collisions on the bridge.

The old median used since the 1960s.

Because traffic is greater going toward the city during the morning and away from it in the evening, the barriers in the middle must be moved to increase or decrease the number of northbound or southbound lanes. There are six lanes in all, so this typically means that in the morning, there will be four inbound and two out; in the evening, three and three is ideal.

The new barriers.

The new barriers.

The problem has been the small plastic batons that give almost no protection against crossing into oncoming traffic. That is about to change, however, as a new system has been implemented that will make the barrier far less penetrable. They look like normal road barriers that you would see on any highway, but when they need to be moved to accommodate rush hour traffic, watch out. They become a huge urban zipper of sorts.

The system has been successful on reversible-lane bridges such as the Auckland Harbour Bridge and Philadelphia’s Walt Whitman Bridge. At 1,500 pounds each, it takes a pair of special trucks to lift them into place. The “Moveable Median Barrier” essentially a chain of linked barriers. The “zipper trucks” can shift them almost as fast as you can drive by them. The $30-million system should “virtually eliminate crossover collisions,” according to the The Golden Gate Bridge District. I just wonder how many wrecks will be caused by people gawking at this cool new barrier system in action.

via CityLab