Warning sign

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Exhibit mostly of various warning signs, Torino automotive museum (some regulatory signs like Do Not Enter also visible).




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, Philippines, 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.



17th century sign along Salvador Street in Alfama says "Year of 1686. His Majesty commands all coaches, seges and litters coming from Salvador's entrance to back up to the same part"
British specimen, circa 1860s.
Early Czech warning signs (circa mid-1930s). The blue signs were later supplanted with red-white-black signs.



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.


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.[2][3][4] 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.

Modern warning sign shapes and colors[edit]


General caution[edit]



Diamond-shaped with reflectors are placed at point of curbs, dividers, or other lane obstacles. Rectangular signs with diagonal stripes indicate solid objects such as barricades, bridge abutments, utility poles or natural obstacles near the roadway. Left side obstacles are marked with stripes running high to low, left to right; right side obstacle signs use stripes running high to low, right to left; in a sense akin to International symbol of arrow pointing down toward side toward roadway.

Animals crossing the roadway[edit]

Signs may warn of wild animals (moose, bear, elk, deer, reindeer, polar bears, camels, wallabies, kangaroos, alligators, etc.) or farm animals (cows, horses, ducks, sheep) that may stray onto the road. In the United States, a SHARE THE ROAD plaque is sometimes placed below these warning signs when used in this manner.

Unusual vehicles in roadway[edit]

Also equipment (tractors, forklifts, snowmobiles, Amish buggies etc.) crossing or traveling along the road.

Road works or construction[edit]

These signs are often temporary in nature and used to indicate road works (construction), poor roads, or temporary conditions ahead on the road including: flagmen, survey crew, single-lane, detour, bridge out, utility crew ahead, blasting area, bump, dip, frost heaves, flooding (or "High water"), soft shoulder, uneven pavement, freshly oiled road, loose gravel, smoke on road, trucks entering, etc. (note that some high water signs are posted to alert drivers of a flood prone area and do not actually mean that there is a flooded section of road ahead) In France, Italy, Spain, Norway etc., warning (and speed limit) signs connected with road works have yellow background, these countries normally have white background on signs. In America and Ireland, signs connected with road works have orange background.

Curves and corners[edit]

These signs indicate that ahead are dangerous or unexpected bends in the road, some being continuous, others being sharp-ended. Signs may indicate whether the curves are to the right or to the left and whether the degree to which the curves or bends are sharp. They may also indicate a series of curves or bends ahead.

Chevrons and arrows[edit]

Chevron shaped symbols or arrows on rectangular signs may be placed at the actual location of the bend or curve to further mark the location of the curve and to assist in negotiation of the curve. They may also be used to indicate "merge" with other traffic, as for an on-ramp of a limited-access highway.



The signs are used to indicate tunnels, where lights are usually required, and a general change in the light level. May also indicate low ceiling clearance. Truck drivers should also watch for prohibited cargo signs (e.g., Hazmat, propane, explosives) upon approach to tunnels.



Traffic signals[edit]


Warning signs for regulatory signs[edit]


Level crossings and intersections[edit]

These signs warn of road crossings at even level (crossroads, T-intersection, forks (Y-intersection), rotary/roundabout). They may also indicate "hidden driveway" intersecting the road ahead. (Compare with bridges/overpasses/viaducts).

Lane starts and ends[edit]


Merge to stay with through traffic[edit]


Roads with one entry point[edit]


End of Roadway[edit]

Pedestrian crossings[edit]




The signs mark school zones (in which lower speed limits may be in place), student crossings, crossing guards or signals ahead. In the U.S. and Canada, pentagon shaped signs are used in place of the usual diamond-shaped signs. The shape of the U.S. school zone resembles a one-room school house and is the only U.S. sign shaped this way. Some Canadian provinces use an identical sign. Ontario uses a white on blue version of this sign.[6]


Other signs with unprotected people[edit]

Fire stations[edit]


Oncoming traffic[edit]


Level crossing/Railway crossing[edit]

These signs are used to warn of level crossings ahead. In most countries a red triangle warning sign is used, with various pictograms for unguarded crossings, crossings with manual gates, and automatic level crossings. In most of Europe an old style gate is used for a crossing with gates, and a steam locomotive for a crossing without gates. Germany uses an electric train. Similar pictograms are also used in Ireland albeit on an amber diamond sign. In the United States the warning of all types of railway crossings is made using a circular yellow sign. The actual crossing is also marked with crossed "Railroad Crossing" crossbuck signs (Stop, look, listen) and possibly lights, bells, and barriers.

Falling rocks[edit]


Other warnings (aircraft-related)[edit]


Crosswinds or Side winds[edit]


Road conditions[edit]



Warning signs with lights[edit]


Non-traffic warning signs[edit]



See also[edit]


  1. ^ Federal Highway Administration. "Section 1A.13 Definitions of Words and Phrases in This Manual". Manual on Uniform Traffic Control Devices (2003 ed.). Washington, DC. p. 1A-14. Retrieved 2009-03-01. "Warning Sign—a sign that gives notice to road users of a situation that might not be readily apparent." 
  2. ^ Defendants get 15-year Prison Sentences for stop-sign killings. CNN Interactive. June 20, 1997. Access date: July 29, 2007.
  3. ^ Stop-sign group challenges sentence. St. Petersburg Times, March 24, 2001
  4. ^ Baillie, Cole, and Miller were sentenced to between 27 and 46 years in prison, but would go free after only five years after a judge ordered a retrial because the prosecutor had overemphasized certain evidence in her closing arguments. The prosecution declined to bring the case a second time.[1] [2]
  5. ^ Highway safety sign becomes running story on immigration | The San Diego Union-Tribune
  6. ^ Driver's Handbook