Minnesota does, and thank you for explaining their purpose! I've been operating under the assumption that the state of MN bought them from Texas, where they move the barriers twice a day to shift the carpool lane from Eastbound to Westbound (or something in that spirit - I'm not sure on the particulars). They've got what looks like an enormous Zamboni that drives along, pulling the barriers over. Works kind of like a zipper, this machine is the zipper head, and the holes and groove at the bottom are the track that the machine follows. I'm clearly not doing a goof job explaining it... I'll search for a link and edit it in if I find one.

Hell, at this point, I can barely remember what brought that to mind in the first place.