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:''For the cartoon series, see Speed Bump. For speed changes in cinematography, see speed ramping.'' Speed bumps (or speed breakers) are the common name for a family of traffic calming devices that use vertical deflection to slow motor-vehicle traffic in order to improve safety conditions. Variations include the speed hump (or speed ramp), speed cushion, and speed table. The use of vertical deflection devices is widespread around the world, and they are most commonly found where vehicle speeds are statutorily mandated to be low, usually , or in car parks. 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 are often found in private car parks (too tall, too sharp an angle for the expected speed), and can be hard to negotiate in vehicles with low ground clearance, such as sports cars, even at very slow speeds. Speed bumps can also pose serious hazards to motorcyclists and bicyclists if not clearly visible, though in some cases a small cut across the bump allows those vehicles to pass through without impediment. Speed bumps cost between $50–200, but have to be replaced after wear.〔(【引用サイトリンク】url=http://www.speedbumpsandhumps.com/ )〕 ==Composition== Each of these devices can be made from a variety of materials, including asphalt, concrete, recycled plastic, metal, or vulcanized rubber. Several trade-offs must be made when selecting the material for a new speed cushion. Traditionally most vertical deflection devices have been constructed of asphalt or concrete; these can be difficult to construct precisely, but have more permanence and greater effect in slowing traffic, due to the material's rigidity and durability. Rubber products are pre-shaped to standardized sizes and thus consistently meet industry standards. It is also easier and to install or remove preformed rubber devices; prefabricated rubber cushions must simply be assembled and bolted down to meet standard specifications, which is particularly beneficial when a city wants to test streets before deciding where to keep the devices. The simple installation process also allows for relocation during the winter when snow is a concern, which prevents damage to the humps by snowplows. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Speed bump」の詳細全文を読む スポンサード リンク
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