chatter bump n. a small depression in a roadbed, usually occurring in series and creating a corrugated or rippled surface. Editorial Note: This term is usually plural. Chatter bumps can occur naturally but they are often simulated at automobile testing courses. (source: Double-Tongued Dictionary)
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This sounds British. I know in the US these are called Rumble Strips.
It’s not explicitly British. All the citations above and most of the uses I found were North American. Also, I don’t believe “rumble strips” are the same things, which is why the editorial note specifies that “chatter bumps” occur naturally (which “rumble strips” do not) and that “chatter bumps” are created artificially for testing purposes of automobiles (which “rumble strips” are not, as far as I can tell).