Last updated on March 31, 2022
“Speed bumps”, as they’re known in US English or more commonly referred as “road humps” or more colloquially “sleeping policemen” by speakers of British English, is a small raised area built across a road to force people to drive more slowly. In Indonesian, the idiom “sleeping policeman” has been calqued into polisi tidur. Literally means the police is/are sleeping. Another term in Indonesian is Alat Pembatas Kecepatan Kendaraan, a trafic speed control device.
Before spreading to languages like Indonesian via loan-translation, the “sleeping policeman” idiom seems to have originated as a variation on an earlier expression, “silent cop” or “silent policeman,” used originally to refer to a structure placed in the middle of an intersection to direct traffic. The OED (Oxford English Dictionary) has a 1934 cite for “silent cop” from Australia and a 1965 cite for “silent policeman” from New Zealand. But the newspaper databases show US cites for “silent cop/policeman” as early as 1914, in cities from Fitchburg, Massachusetts to Racine, Wisconsin:
Fitchburg (Mass.) Sentinel, July 14, 1914, p. 5
The sign works out satisfactorily when the traffic is not heavy, but when there is a rush at this busy corner four vehicles are sometimes circling the silent cop at the same time, and others are coming from all points of the compass.
Hartford (Conn.) Courant, July 26, 1915, p. 7
Danbury has a “silent cop.” At least, that is what Danbury calls it, not recognizing the contradiction contained in the two words. The silent cop consists of a post about five feet high surmounted by a box on each side of which is painted the words “Keep to the Right” and bearing aloft a lantern.
Racine (Wisc.) Journal-News, Aug. 20, 1915, p. 12
Chief Baker stated at that time that he had purchased six silent policemen, in other words, signs to be placed at the intersection of busy street corners directing vehicles to turn to the left or right and that it would possibly stop, to a great extent, violation of the rules of the road.
By the late 1920s, “silent policemen” had evolved into the forerunners of automatic traffic lights, and variants could be found around the globe. (In Australia, the “silent cop” was evidently never more than a small metal protrusion around which traffic flowed.) “Sleeping policemen,” on the other hand, wouldn’t emerge for another several decades. I don’t know where in the English-speaking world the expression originated, though the UK seems likely. The earliest British cite for the term currently given by the OED is from 1973, but this can no doubt be antedated, perhaps by a decade or so. The earliest US cite I’ve found so far is from Bennington, Vermont in 1967:
Bennington (Vt.) Banner, May 11, 1967, p. 4
Building big bumps — known as sleeping policemen — in the streets of Old Bennington as a deterrent to speeders would indeed be an effective way to discourage motorists from stomping too hard on their accelerators.
The term was used in various other American municipalities in the late ’60s. To the right is a photo that appeared in the May 4, 1969 Chicago Tribune showing a “sleeping policeman” on a park road in Decatur, Illinois, complete with a warning sign very much like the one in the L.A. Lights advertisement.
The expression didn’t seem to have much staying power in the US, but it caught on in many other parts of the world with more of a British influence, such as Jamaica and Belize. A Jan. 30, 1968 letter to the editor in the Jamaican newspaper The Gleaner explained that “many private roads in Kingston have installed ‘Sleeping Policemen'” and urged the local authorities to install more. A year or two later “sleeping policemen” had indeed become more prevalent in Jamaica. A Dec. 7, 1969 UPI wire story in the Oakland Tribune explained: “When you hear a Jamaican talk about his country’s ‘sleeping policemen,’ he isn’t implying that Jamaican lawmen aren’t wide awake. The term ‘sleeping policeman’ is used to describe the hump built across streets to slow down speeders.”
While “sleeping policeman” was making its way around the Anglosphere, equivalents in other languages began popping up. Mexico has policia durmiendo, while France and Switzerland have gendarme couché. There’s an entry for gendarme couché in the Dictionnaire Suisse Romand, with some discussion of “sleeping policeman” as well. The entry implies that there isn’t enough information to determine which expression is a calque of the other, but “sleeping policeman” appears to win out, unless someone can find citations for gendarme couché earlier than those above. It’s also notable that couché means ‘lying down, resting, recumbent,’ a slightly different sense from “sleeping.” Equivalents in some eastern European languages seem to have been calqued from the French expression, such as Hungarian (fekvőrendőr), Estonian (lamav politseinik), and Latvian (guļošais policists).
Edited from the article posted on Language Log by Benjamin Zimmer at March 14, 2007