A speed bump (British English a speed or road hump, sometimes colloquially a sleeping policeman) is a traffic calming tool designed to slow traffic. A speed bump is a bump in a roadway that may be circular, parabolic, or sinusoidal, and it may have gaps near the curb to allow drainage. The speed at which a vehicle can safety pass a bump decreases with the bump's slope. Speed bump heights range from as little as 2 inches to as much as 6 inches, and they can vary in length from less than 1 foot (30cm) to as much as 10 feet (3m). Speed bumps longer than 10 feet are usually called speed humps, and they are often used to slow traffic in residential neighborhoods.

The use of speed bumps is widespread around the world, and they are most commonly found where prevailing vehicle speeds are expected to be low.

Although speed bumps are very effective in keeping vehicle speed down, their use is sometimes controversial as they can cause noise and possibly vehicle damage if taken at too great a speed. Poorly designed speed bumps often found in private car parks (too tall, too sharp an angle for the expected speed) can be hard to negotiate in vehicles with low ground clearance, such as sports cars, even at very slow speeds.

History

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The speed bump was invented in the 20th century. Prior to the invention of the automobile and the widespread use of smooth asphalt or concrete pavement, street vehicles could not travel at the sort of speeds at which speed bumps are effective.

On March 7, 1906, the New York Times reported that Chatham, New Jersey planned to install what were probably the first automobile speed bumps/humps ever. According to the article, Chatham planned to raise its crosswalks five inches above the road level, adding, "This scheme of stopping automobile speeding has been discussed by different municipalities, but Chatham is the first place to put it in practice."

Another speed bump genesis story takes place during World War II in New Guinea. US Army Colonel Edgar Rothkrug was working as an engineer for the Army Corps of Engineers where they were testing the amphibious tanks.^{href="http://articles.gourt.com/en/Wikipedia:Citing sources">Citing sourcesArticles lacking sources} The story is simple: the warehouse was on one side of the street and the boat launch ramp was on the other. Apparently the Military Police were not watching the speed as well as they should have because cars would speed along that road endangering the men crossing to launch the tanks. Realising that drivers slow down for potholes, Rothkrug had his men pour down concrete to create a raised bump to slow down drivers. It worked exceptionally and since cars did not have seatbelts then, some drivers were actually ejected from the jeeps. Being an invention in the military, the army took the patent for the speed bump but credited the inventor by naming it the "Rothkrug bump" in army manuals.^{href="http://articles.gourt.com/en/Wikipedia:Citing sources">Citing sourcesArticles lacking sources}

The first speed bump in Europe was built in 1970 in the city of Delft in the Netherlands.

Road humps in the UK

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In the UK, vertical deflection in the highway designed for Traffic calming is of the following forms:

• Road hump is the most common variety which are usually round-topped.
• Speed table is a type of hump with a central plateau which is both long and broad. It may include a pedestrian crossing. This type are preferred by some emergency services and bus operators
• Speed Cushion is a raised portion of road with a flat top only extending over part of the carriageway width. Cushions can be used singly, in a pinch point, or in pairs or triples.
• Rumble strips - Uneven road surface which is now only used in rural areas and retail parks because of the noise.

The Department for Transport defines the regulations for the design and use of road humps .

Criticisms

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The Association of British Drivers, National Motorists Association (US), and individual websites like Americans Against Traffic Calming and No Speed Bumps are critical of speed bumps. Their arguments include that speed bumps:

• can impede or slow emergency vehicle access to areas.
• kill more people than they save, mainly due to the aforementioned delays in providing timely emergency service^**.
• can encourage rapid acceleration and speed increases in certain spots as drivers attempt to make up for time lost slowing down for the bumps.
• increase pollution^*.
• are a substitute for a lack of enforcement.

Another possible source of criticism is that speed bumps on roads and parking lots other than public ones are not necessarily designed according to any kind of accepted standard, so they may be more hazardous to some road users. For instance, a rubber bolt-on one with an abrupt edge can catch the tire of a bicycle and cause an accident.

References

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• Department of Transport (UK) Highways (Road Humps) Regulations 1996
• New York Times, "Democratic Rate Plan Favored by Roosevelt other news", Mar 7, 1906. pg. 3.
• Klaus Schlabbach, "Traffic Calming in Europe" Institute of Transportation Engineers

Bibliography

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• London Assembly, London's got the hump, April 2004. An examination of speed humps conducted by the London Assembly’s Transport Committee.

Road infrastructure | Urban studies and planning | Road transport | Road safety | Controversial road traffic legislation

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