The Golden Gate bridge has to handle a huge amount of traffic. So much traffic that it has to be able to change lanes frequently throughout the day as rush hour tends to flow in various directions. To keep things moving smoothly, the overseers of this bridge utilize what's called the Road Zipper. It's a specially designed truck that moves back and forth over the center row of movable barriers to simultaneously open and close various lanes of traffic. If you're ever on the bridge at key times during the day then you've probably seen this important piece of equipment in action.
