The Golden Gate Bridge's $26.5 million movable median barrier project is underway, with construction expected to begin this fall. But since the median has to be assembled on the famous Bridge, officials say they'll have to completely close the span to get the barrier in place.

The 11,538-foot-long steel and concrete median, which is intended to prevent head-on collisions, will have a "zipper truck" system to move the 800 separate 1,500 pound pieces of the barrier into the proper lane configurations (here's a 2008 rendering of how that might look).

What's holding those 800 pieces of barrier in place? Oh, just gravity, with an internal spring system that will make it "strong enough to absorb major impacts without moving." Tell it to this guy.

According to the Marin Independent Journal, the barrier could be in place as soon as October of this year, following the first and longest closure of the Bridge's existence.

"The bridge has been closed only for weather, namely high winds," the IJ reports, "but never for much more than three hours, bridge officials said. In 1987 it was closed to vehicle traffic for the span's 50th birthday, but was open to pedestrians."

This year, however, the Bridge will completely close for a full 52-or-so hours on a yet-to-be-determined Friday-Sunday in October. Along with the placement of the barrier, workers will also have some work to do on the toll plaza, as they install crash cushions and demolish four toll booths to make room for the median and related equipment.