For reasons I don't care to contemplate, I spent some time recently in Austin, Texas. It's a weird place (though I dug the food). They have something a lot like what we up here in the Frozen North call "speed bumps", but they call them "road humps" instead.
A speed bump is a "traffic calming" device: A rounded bar or moraine of asphalt about four inches high and two feet broad, stretching across the width of a road. It's usually painted yellow. The idea is to encourage people to drive more slowly, by rattling their teeth and wrecking their suspension if they don't.
"Road humps" are about the same, but they're more like five or six feet across, and higher as well. The term is more picturesque, isn't it? I doubt that either design is more effective than the other; it's just a matter of local style, I suppose.