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A speed bump (British English a speed or road hump, sometimes colloquially a sleeping policeman) is a traffic calming tool designed to slow traffic or reduce through 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 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 intended to reduce. 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 . 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 . The first speed bump in Europe was built in 1970 in the city of Delft in the Netherlands . Road humps in the UK In the UK, vertical deflection in highways, designed for Traffic calming, is of the following forms: The Department for Transport defines the regulations for the design and use of road humps . Criticisms The Association of British Drivers is critical of speed humps claiming: Other criticisms of speed bumps, include: Dynamic speed bumps Dynamic speed bumps are a recent innovation which differ from conventional speed bumps by only activating if a vehicle is travelling above a certain speed. Vehicles travelling below this speed will not experience the discomfort of a conventional speed bump. Dynamic speed bumps may allow the passage of emergency vehicles at higher speeds. In a design by British company Dunlop Transcalm, a rubber housing is fitted with a pressure valve which determines the speed of a vehicle. If the vehicle is travelling below the set speed the valve opens allowing the bump to deflate as the vehicle drives over it, but remains closed if the vehicle is travelling too fast. The valve can also be set to allow heavy vehicles, such as fire trucks, ambulances and buses to cross at higher speeds. Dunlop Transcalm claim that their dynamic speed bumps reduce or eliminate negative effects of speed bumps such as increased noise and pollution, uneven traffic speed, and impeding emergency vehicles. Each 'smart hump' reportedly costs between £2,500 and £4,850. Bibliography | ||||||||
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