Warning sign

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A warning sign is a type of sign which indicates a potential hazard, obstacle, or condition requiring special attention. Some are traffic signs that indicate hazards on roads that may not be readily apparent to a driver.^[1]

While warning traffic sign designs vary, they usually take the shape of an equilateral triangle with a white background and thick red border. In the People's Republic of China (except for Macau and Hong Kong), they appear with a black border and a yellow background. In Sweden, Serbia, Bosnia and Herzegovina, Greece, Finland, Iceland, North 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 and 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,^[2] most of South America, and also Ireland (diverging from the standards of the rest of Europe) 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.