The Golden Gate Bridge just got the new median it so desperately needed to prevent head-on collisions, but one neat feature about it is that it moves. Well, not on its own. It needs a truck to do that, and specifically, it needs what's known as a "zipper truck." And it's called that because it makes the median actually look like a big zipper.
As Gizmodo noted, 16 people have died on the bridge in head-on collisions since 1971, which is 16 people too many. At the same time, installing a normal concrete median would be impractical, as the bridge itself doesn't always maintain a constant traffic flow pattern. Like most bridges, the amount of traffic in each direction varies based upon the time of day, and the new median – with its accompanying zipper truck – allows traffic authorities to maintain the flow. So in the mornings, one direction could have four lanes of traffic, while the other direction has three, and in the evenings, the opposite happens.
But the end result is that the zipper truck looks like its zipping, or rather slurping, the median up.
And if you think the zipper truck and the medians are all silly business, well then you're silly, but also, the way they used to do it before was pretty nuts. Not just with pylons that marked off lanes, but didn't do anything by way of protection, but by a guy putting the pylons in manually. While sitting on a truck, and very nearly completely exposed to busy, speeding traffic: