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A traffic warning sign is a type of traffic sign that indicates a hazard ahead on the road that may not be readily apparent to a driver. In most countries, they usually take the shape of an equilateral triangle with a white background and a thick red border. However, both the color of the background and the color and thickness of the border varies from country to country. In the People's Republic of China (except for Macau and Hong Kong), warning signs appear with a black border and a yellow background. In Sweden, Serbia, Bosnia and Herzegovina, Greece, Finland, Iceland, the Republic of Macedonia and Poland, they have a red border with an amber background. The polar bear warning sign in Svalbard recently changed from displaying a black bear on white background to a white bear on black background (both signs are triangular with a red border). Some countries (like France, Norway, Spain) that normally use a white background have adopted an orange or amber background for road work or construction signs. Warning signs in some countries have a diamond shape in place of the standard triangular shape. In the United States, Canada, Mexico, Thailand, Australia, Japan, Indonesia, Malaysia, New Zealand, most of South America, and also Ireland (diverging from the standards of the rest of Europe) use warning signs are black on a yellow background and usually diamond-shaped, while temporary signs (which are typically construction signs) are black on an orange background. Some other countries also use these standards for some signage. The warning signs usually contain a symbol. In Europe they are based on the UNECE Vienna Convention on Road Signs and Signals. In the United States they are based on the MUTCD standard and often contain text only. == History == Some of the first roadside signs —ancient milestones— merely gave distance measures. Hazard warnings were rare though occasional specimens appeared, such as the specific warning about horse-drawn vehicles backing up which was carved in stone in Lisbon's Alfama neighborhood in 1686. The early signs did not have high-contrast lettering and their messages might have been easily overlooked. Signs were written in the local language (example); symbolic signs, though long used on certain tradesmen's signs (like the pawnbrokers' tri-ball symbol) were to be used for traffic only much later in history. Complex signage systems emerged with the appearance of motorcars. In 1908 the automobile association in West London erected some warning signs. In 1909, nine European governments agreed on the use of four pictorial symbols, indicating ''bump'', ''curve'', ''intersection'', and ''railroad crossing''. The intensive work on international road signs that took place between 1926 and 1949 eventually led to the development of the European road sign system. As the 20th century progressed and also as traffic volume and vehicle speeds increased, sign-visibility and nighttime use capability gained significance. Earlier flat painted signs gave way to signs with embossed letters. Circa 1940-50 in countries with many vehicles, wording might be spelled out with so-called "button copy" —letters dotted with reflective glass spheres for night visibility. Button copy signs with plastic pips rather than glass appeared in the 1970s. Flat metal signs reappeared in the 1980s with the widespread use of surfaces covered with retroflective sheeting materials like Scotchlite. In Europe, the 1968 Vienna Convention on Road Signs and Signals (which became effective in 1978) tried, among other things, to standardize important signs. After the fall of the Iron Curtain and greater ease of country-to-country driving in the Eurozone, European countries moved toward lessening the regional differences in warning signs. In modern regulations, U.S. warning signs are classified as ''Series W'' signs, such as: W1 Series (curves and turns), W2 Series (intersections), W22 Series (blasting), et cetera, ending with the W25 Series (concerning extended green traffic lights). Some U.S. warning signs are without category while others like the warning stripes at tunnel portals or plain red ''End of Roadway'' signs are classified as Object Markers (OM Series). In the U.S., ''Stop'' and speed limit signs fall under the R Series (Regulatory). Modern U.S. signs are widely standardized; unless they are antique holdovers from an earlier era, oddities like a yellow ''Stop'' sign or a red ''Slippery When Wet'' sign would typically appear only on private property —perhaps at a hospital campus or in a shopping mall parking lot. Street sign theft by pranksters, souvenir hunters, and scrappers has become problematic: removal of warning signs can contribute to traffic collisions and also costs municipalities money to replace lost signs. Some authorities affix theft-deterrence stickers to the back sides of their signs. Some jurisdictions have criminalized unauthorized possession of road signs or have outlawed their resale to scrap metal dealers. In come cases, thieves whose sign-removal lead to road fatalities have been charged with manslaughter.〔(【引用サイトリンク】title=CNN - Defendants get 15-year prison sentences for stop-sign killings - June 20, 1997 )〕〔(【引用サイトリンク】title=Florida Defendants Get Retrial on Manslaughter Convictions Resulting from Deaths at Intersection Where Stop Sign Downed; Dissenting Judge Argues for Acquittal )〕〔(【引用サイトリンク】title=Tampabay: Suddenly, stop sign case is over )〕 Artistically inclined vandals sometimes paint additional details onto warning signs: a beer bottle, a handgun, or a boom box added to the outstretched hand of the ''Pedestrian Crossing'' person, for example. 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「warning sign」の詳細全文を読む スポンサード リンク
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