The Golden Gate Bridge’s Road Zipper is an Awesome Traffic Control Vehicle!
It’s basically very simple, a bi number of commuters go across the bridge one way to get to their jobs in the morning to you would need an extra lane in order to deal with traffic, and pretty much the same number of vehicles need to transport their occupants in the afternoon to get them home in time for dinner.
Wo how do the Golden Gate bridge authorities handle this situation with high volume traffic? Well they have made a movable road barrier made out of metal and concrete that are semi-rigid and movable. Well not by hand apparently given the weight but by a special machine aptly named the Road Zipper and they transfer the Moveable Median Barrier (or MMB) from one lane to the other depending on which time of the day it is.
A pretty elegant solution to a problem, check out the video to see how it looks.