Editing Traffic warning sign

{{Short description|Sign that warns people for a risk or danger}}
{{Redirect |Warning Sign}}
{{About||a sign on a boat or building relating to it or its contents|Placard|non-traffic warning signs|Safety sign}}
{{Multiple issues|
{{Original research|date=December 2017}}
{{More citations needed|date=December 2017}}
}}
[[File:-01 Museo Nazionale dell'Automobile di Torino segnali stradali.jpg|thumb|right|alt=Refer to caption|Exhibit mostly of warning signs (with some [[regulatory sign]]s like ''Do Not Enter'') at the [[Turin Automobile Museum]]]]

A '''warning sign''' is a type of [[sign]] which indicates a potential hazard, obstacle, or condition requiring special attention. Some are [[traffic sign]]s that indicate hazards on roads that may not be readily apparent to a driver.<ref>{{cite book|last1=Federal Highway Administration|author-link1=Federal Highway Administration|title=Manual on Uniform Traffic Control Devices|url=https://mutcd.fhwa.dot.gov/|access-date=2009-03-01|edition=2003|location=Washington, DC|page=1A–14|chapter=Section 1A.13 Definitions of Words and Phrases in This Manual|chapter-url=http://mutcd.fhwa.dot.gov/htm/2003r1r2/part1/part1a.htm|quote=Warning Sign—a sign that gives notice to road users of a situation that might not be readily apparent.|ref=2003MUTCD|archive-date=2019-11-11|archive-url=https://web.archive.org/web/20191111063902/https://mutcd.fhwa.dot.gov/|url-status=live}}</ref>

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]] (excluding [[Macau]] and [[Hong Kong]]) and [[North Korea]], they appear with a black border and a yellow background. In [[Sweden]], [[Greece]], [[Finland]], [[Iceland]], [[Poland]], [[Cuba]], [[Nigeria]], [[South Korea]] and [[Vietnam]], they have a red border with an [[amber (color)|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]], [[Australia]], [[Japan]], [[Liberia]], [[Sri Lanka]], [[New Zealand]],<ref>{{Cite news |date=2013-12-05 |title=Permanent Warning Signs in New Zealand |url=https://www.drivingtests.co.nz/resources/permanent-warning-signs-in-new-zealand/ |url-status=live |archive-url=https://web.archive.org/web/20180820005820/https://www.drivingtests.co.nz/resources/permanent-warning-signs-in-new-zealand/ |archive-date=2018-08-20 |access-date=2018-08-19 |newspaper=Driving Tests Resources}}</ref> most of [[Central America|Central]] and [[South America]], some countries of [[Southeast Asia]], and also [[Republic of Ireland|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, like [[Argentina]] and [[Taiwan]], use a combination of triangle and diamond-shaped warning signs.

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 [[Manual on Uniform Traffic Control Devices|MUTCD standard]] and often contain text only.

== History ==
[[File:Redundant sign - geograph.org.uk - 467503.jpg|thumb|right|200px|Pre-standardization British ''School Zone'' with metal-cutout generic ''Warning'' symbol embellished with red glass [[Cat's eye (road)|reflector-spheres]]]]

Some of the first roadside signs&mdash;ancient [[milestone]]s&mdash;merely gave distance measures. Hazard warnings were rare though occasional specimens appeared, such as the specific warning about [[horse-drawn vehicle]]s 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 ([[commons:File: Spenge-Werburg-Torhaus-Schild-20050114 1519 1970-800px.jpg|example]]);  symbolic signs, though long used on certain tradesmen's signs (like the [[History of pawnbroking#Symbol|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 traffic volume and vehicle speeds increased, so did the importance of road sign visibility.  Earlier flat-painted signs gave way to [[commons:File: Steep Hill and Level Crossing Pre-Worboys road signs Coventry Transport Museum.jpg|signs with embossed letters]], which in turn gave way to [[button copy]] signs&mdash; round [[retroreflective]] "buttons" helped to achieve greater night visibility. Flat metal signs reappeared in the 1980s with the widespread use of surfaces covered with [[retroflective sheeting]] materials like [[Scotchlite]].

In Europe, 1968 [[Vienna Convention on Road Signs and Signals]] (which became effective in 1978) tried, among other things, to standardize important signs.  After the [[revolutions of 1989|fall of the Iron Curtain]] and greater ease of country-to-country driving in the [[EU]], European countries moved toward lessening the [[Comparison of European road signs#Table of traffic signs comparison|regional differences in warning signs]].

In modern regulations, [[Road signs in the United States#Warning signs|U.S. warning signs]] are classified as ''Series W'' signs, starting with the W1 Series (curves and turns) and ending with the W25 Series (concerning extended green [[traffic light]]s). Some [[Road signs in the United States#Miscellaneous|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 [[Manual on Uniform Traffic Control Devices|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&mdash;perhaps at a hospital campus or in a [[shopping mall]] parking lot.

[[Street sign theft]] by pranksters, souvenir hunters, and [[Metal theft|scrappers]] has become problematic: removal of warning signs costs municipalities money to replace lost signs, and can contribute to traffic collisions. Some authorities affix [[:File:Streetsign theft warning.jpg|theft-deterrence stickers]] to the back sides of signs. Some jurisdictions have criminalized unauthorized possession of road signs or have outlawed their resale to scrap metal dealers. In some cases, thieves whose sign-removal lead to road fatalities have been charged with [[manslaughter]].<ref>{{Cite web |date= June 20, 1997 |title=Defendants Get 15-Year Prison Sentences for Stop-Sign Killings |url=http://www.cnn.com/US/9706/20/stop.sign/index.html |url-status=live |archive-url=https://web.archive.org/web/20121108123606/http://www.cnn.com/US/9706/20/stop.sign/index.html |archive-date=November 8, 2012 |access-date=October 6, 2012 |website=CNN Interactive}}</ref><!-- 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. --><ref>{{Cite web |title=Florida Defendants Get Retrial on Manslaughter Convictions Resulting from Deaths at Intersection Where Stop Sign Downed; Dissenting Judge Argues for Acquittal |url=http://www.usroads.com/journals/rilj/0110/ri011001.htm |url-status=dead |archive-url=https://web.archive.org/web/20120305211030/http://www.usroads.com/journals/rilj/0110/ri011001.htm |archive-date=2012-03-05 |access-date=2012-10-06 |website=Road Injury Prevention & Litigation Journal}}</ref><ref>{{Cite news |last=Karp |first=David |date=May 22, 2001 |title=Suddenly, Stop Sign Case is Over |work=St. Petersburg Times Online |url=http://www.sptimes.com/News/052201/TampaBay/Suddenly__stop_sign_c.shtml |url-status=dead |access-date=2012-10-06 |archive-url=https://web.archive.org/web/20121017190929/http://www.sptimes.com/News/052201/TampaBay/Suddenly__stop_sign_c.shtml |archive-date=2012-10-17}}</ref> 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 traffic warning sign shapes and colors ==
{{Commons|Warning road sign}}
[[File:Road Warning signs around the World.svg|thumb|right|upright=2|alt=Colour-coded political world map (refer to caption)|
{{center|Shape and colors of road warning sign used:}}
{{legend|#FFBE28| Uses [[File:Diamond warning sign.svg|20px|alt=Yellow diamond sign with thin black border]]}}
{{legend|#FF6600| Uses [[File:Diamond warning sign.svg|20px|alt=Yellow diamond sign with thin black border]], previously used [[File:UK traffic sign 500.svg|20px|alt=White triangular (point up) sign with thick red border]]}}
{{legend|#C8141E| Uses [[File:UK traffic sign 500.svg|20px|alt=White triangular (point up) sign with thick red border]]}}
{{legend|#003C8C| Uses [[File:UK traffic sign 500.svg|20px|alt=White triangular (point up) sign with thick red border]], previously used [[File:Triangle warning sign (red and blue).svg|20px|alt=Blue triangular (point up) sign with thick red border]]}}
{{legend|#820082| Uses a combination of [[File:Diamond warning sign.svg|20px|alt=Yellow diamond sign with thin black border]] [[File:UK traffic sign 500.svg|20px|alt=White triangular (point up) sign with thick red border]]}}
{{legend|#2882FF| Uses [[File:Triangle warning sign (red and yellow).svg|20px|alt=Yellow triangular (point up) sign with thick red border]]}}
{{legend|#009664| Uses [[File:Triangle warning sign (black and yellow).svg|20px|alt=Yellow triangular (point up) sign with thick black border]]}}
{{legend|#aaa| No information}}]]
Warning signs can indicate any potential hazard, obstacle or condition requiring special attention. Some of the most common warning signs are the following.

=== General caution ===
[[File:Vienna Convention road sign Ab-32-V1.svg|Yellow diamond with black symbol|thumb|120px|right]][[File:Vienna Convention road sign Aa-32-V1.svg|thumb|100px|left|White background red triangle with black symbol]]
[[File:Vienna Convention road sign Aa-32-V3.svg|thumb|100px|left|Amber background red triangle with black symbol]]

General warning signs are used in instances in which the particular hazard, obstacle or condition is not covered by a standard sign. In Europe, they usually comprise an [[exclamation mark]] on the standard triangular sign ([[Unicode]] {{unichar|26A0|WARNING SIGN}}) with an auxiliary sign below in the local language identifying the hazard, obstacle or condition. In [[Sweden]], the general warning sign has only a vertical line instead of exclamation mark; this model was used also in many other European countries until the 1990s. In the [[United States]] and other countries using diamond-shaped signs, the explanatory language is often written directly on the diamond-shaped sign, although it may contain only a general warning such as "Caution", and pictograms may also be used.

=== Obstacles ===
Warning signs can be placed in advance of, next to or on a specific obstacle. Obstacles such as railway level crossings may have several warning signs beforehand, while bridge ramparts typically have reflective signs placed directly on them on either side. These signs can be specific to the shape requirements of the obstacle, for example, bridge rampart signs are often tall and skinny so as not to intrude into the lane.

=== Curves and corners ===
[[File:Vienna Convention road sign Ab-1b-V1.svg|thumb|120px|left|Vienna Convention dangerous bends sign (diamond-shaped)]]
[[File:New Zealand road sign W12-2.1-L.svg|thumb|120px|left|New Zealand double sharp curve to the left sign]]

These signs indicate that dangerous or unexpected bends in the road are ahead. Signs typically indicate whether the curves are to the right or to the left, the angle of the curve and whether it is one curve or a series of curves.

==== Chevrons and arrows ====
[[File:Philippines road sign HM 1B R.svg|thumb|120px|right|Philippines curve chevron]]

[[Chevron (insignia)|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 the 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]].
<br>
An unusual occurrence of the rectangular arrow sign appears on the eastbound approach to [[Dead Man's Curve#Ohio|Dead Man's Curve]] in [[Cleveland, Ohio]], US, a curve so sharp that in places an arrow's stem is printed on one sign and the arrow's point is printed on another larger sign further down the road; from the driver's perspective at a distance, the two signs visually blend together to form one large arrow image.

=== Steep hills ===
[[File:Vienna Convention road sign Aa-2a-V1-1.svg|10% down grade sign (white triangle)|thumb|120px|left]]

Truck drivers will need to pay attention to "Steep grade" warnings (or "Down grade, use lower gear"), sometimes posted with the percent grade (e.g., 12%<!-- leave this percent sign - that's what the signs show, not "12 percent" -->). Steep hills may also feature "Runaway truck escape" or "Emergency stop" areas with corresponding signs. The [[United Kingdom|UK]] has a sign warning of "Adverse [[superelevated turn|camber]]" on a curve.

=== Lane starts and ends ===
[[File:Vienna Convention road sign Ab-4b-V1-1.svg|thumb|120px|right|Vienna Convention carriageway narrows sign (yellow diamond)]]

These signs indicate when a multilane highway is being narrowed, when a passing lane is ending, or where the road is widening or a passing lane starting. Another type of sign is used to indicate central "two-way" left turning lane in center of roadway. Warning signs may also warn of "Highway ends", where the road changes class or type.

=== Merge to stay with through traffic ===
[[File:Vienna Convention road sign Ab-19c-V2-1.svg|thumb|120px|left|Vienna Convention merging traffic sign (yellow diamond)]]

In the [[United States]] and [[Canada]], there is special signage for lanes that are about to exit, so that drivers who wish to remain on the main road have adequate time to merge. Such lanes are sometimes indicated by special striping ("alligator stripes") and the sign, "Through Traffic Merge Left" (or right). On freeways, the green directions sign for the exit ramp may have the additional notation, "Exit Only", and should have black letters on a yellow background for emphasis.

=== Bridges ===
[[File:Vienna Convention road sign Aa-5-V1.svg|thumb|120px|right|Vienna Convention [[drawbridge]] ahead sign (white triangle)]]
[[File:New Zealand road sign W13-2.svg|thumb|120px|left|New Zealand narrow bridge ahead sign]]

These signs are used where traffic may be constricted to a narrow bridge, or where the bridge may have a movable span closed to vehicles while boats pass (e.g., [[drawbridge]]). They may also be used for underpass to indicate low overhead clearance.

=== Tunnels ===
[[File:MUTCD-CA SW37.svg|thumb|120px|left|United States (California)]]

These signs are used to indicate [[tunnel]]s, where lights are usually required, and a general change in the light level. May also indicate low [[ceiling]] [[Engineering tolerance|clearance]]. Truck drivers should also watch for prohibited cargo signs (e.g., [[propane]]) upon approach to tunnels.

=== Road conditions ===
[[File:Vienna Convention road sign Aa-34-V1-EA.svg|thumb|upright=0.54|left|Vienna Convention slippery road because ice or snow (white triangle)]]

Warns road users of severe road conditions ("Icy road", "Bump", etc). Also "Loose gravel", "Soft shoulder", "[[Speed hump]]", and "Watch for ice".

=== Falling rocks ===
[[File:Vienna Convention road sign Aa-11a-V1.svg|thumb|120px|right|Vienna Convention falling rocks sign (white triangle)]]

These signs may be used to indicate the hazards of fallen or falling rocks on the road ahead. They are usually pictographs, but may also include wording, such as "falling rocks". In [[Italy]] the words may be "{{lang|it|caduta [[wikt:sassi#Italian|sassi]]}}" or "{{lang|it|caduta massi}}"; in [[France]] "{{lang|fr|chute de pierres}}"; in [[Mexico]] "{{linktext|derrumbe|lang=es}}s".

=== Pedestrian crossings ===
[[File:Vienna Convention road sign Aa-12c-V1.svg|thumb|120px|right|Vienna Convention pedestrian crossing sign (white triangle)]]

These signs are used to warn drivers of people walking in the street. They may also be used to warn of children playing, playgrounds, bicycle area, deaf child, blind pedestrians, and thickly settled zones where pedestrians may enter the road.

In [[California]], [[United States]] near the [[Mexican border (US)|Mexican border]], there were [[Immigration sign|warning signs showing a running family]]. This was to warn motorists to look out for [[Illegal immigration|illegal immigrants]] who try to escape [[United States Border Patrol|authorities]] by running through freeway traffic. The symbol was created by [[California Department of Transportation]] employee John Hood in the late 1980s.<ref>{{Cite news |last=Berestein |first=Leslie |date=April 10, 2005 |title=Highway Safety Sign Becomes Running Story on Immigration |work=SignOnSanDiego.com |url=http://www.signonsandiego.com/uniontrib/20050410/news_1n10signs.html |url-status=dead |access-date=2006-07-14 |archive-url=https://web.archive.org/web/20060628040209/http://www.signonsandiego.com/uniontrib/20050410/news_1n10signs.html |archive-date=2006-06-28}}</ref>

=== Schools ===
[[File:Vienna Convention road sign Ab-13-V1-LHT.svg|thumb|120px|left|Vienna Convention school crossing ahead (yellow diamond, LHT version)]]

These 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 schoolhouse]] and is the only U.S. sign shaped this way. Some Canadian provinces use an identical sign.

=== Bicycles ===
[[File:Vienna Convention road sign Aa-14-V1.svg|thumb|120px|right|Vienna Convention bicycle crossing ahead (white triangle)]]

Bicycle crossing signs warn that bicycles will cross at their location.

=== Animals crossing the roadway ===
[[File:Vienna Convention road sign Ab-15b-V1-LHT.svg|thumb|120px|right|Vienna Convention wild animal crossing (yellow diamond, LHT version)]]
[[File:New Zealand road sign W18-3.1.svg|thumb|120px|left|New Zealand cows ahead sign]]
[[File:New Zealand road sign W18-3.2.svg|thumb|120px|left|New Zealand sheep ahead sign]]
[[File:MUTCD W11-17.svg|thumb|120px|right|U.S. sheep area sign]]

These signs warn of animals that may stray onto the road. They can be either wild (as with deer or moose) or farm animals (as with cows or ducks). 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 ===
[[File:UK traffic sign 582.svg|thumb|left|120px|United Kingdom: military vehicles crossing.]]
[[File:New Zealand road sign W18-5.svg|thumb|left|120px|New Zealand: fire trucks.]]

These signs are found where road users can encounter slow, large or non-typical vehicles such as forklifts, handcarts and military vehicles. They are more common around quarries, airports, industrial zones, military installations and rural areas.

=== Road work or construction ===
[[File:New Zealand road sign W1-1A.svg|thumb|120px|right|New Zealand road work sign]]

These signs are often temporary in nature and used to indicate road work (construction), poor roads, or temporary conditions ahead on the road including flagmen, uneven pavement, 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 work have a yellow background in place of the usual white background on signs. In North America and Ireland, signs connected with road work have an orange background.

=== Traffic signals ===
[[File:Vienna Convention road sign Aa-17a-V1.svg|thumb|120px|left|Vienna Convention traffic signal ahead (white triangle)]]

These warning signs indicate that [[Traffic signal|traffic lights]] are ahead, and are often used when it is difficult to see that a traffic light may already be showing red, to warn a driver to prepare to slow down. They may be supplemented with flashing light or lighted sign when light is red or turning red. Some countries also have signs warning of signals for [[ramp meter]]s, fire stations, and airfields.

=== Intersections ===
[[File:Vienna Convention road sign Ab-18b-V1.svg|thumb|120px|left|Vienna Convention intersection sign (diamond-shaped)]]
[[File:NZ road sign W11-2.svg|thumb|120px|left|New Zealand intersection with priority sign]]

These signs warn of road crossings at crossroads, T-intersections, roundabouts, or Y-intersections. They may also indicate "hidden driveway" intersecting the road ahead. (Compare with bridges, [[overpass]]es, [[viaduct]]s).

=== Warning signs for regulatory signs ===
[[File:Vienna Convention road sign Aa-21a-V1.svg|thumb|120px|right|Vienna Convention stop ahead sign (white triangle)]]
[[File:NZ road sign W10-1.svg|thumb|120px|left|New Zealand stop ahead sign]]
[[File:NZ road sign W10-2.svg|thumb|120px|left|New Zealand give way ahead sign]]

Like for traffic signals, some [[stop sign|"stop"]] or [[yield sign|"yield" sign]]s may require additional warning or reminder, especially in dense areas or where the sign has been added recently.

=== Oncoming traffic ===
[[File:Vienna Convention road sign Aa-23-V1.svg|thumb|120px|right|Vienna Convention two-way traffic sign (white triangle)]]

These signs may be used to warn people of oncoming traffic; shown when a [[motorway]] becomes a [[dual carriageway]] or a normal road without a [[central reservation]] or median.

=== Level crossing (railway crossing) ===
[[File:Vienna Convention road sign Ab-25-V1.svg|thumb|120px|left|Vienna Convention protected level crossing sign (yellow diamond)]]

These signs are used to warn of [[level crossing]]s 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 [[boom barrier|barrier]]s.

=== Low flying aircraft ===
[[File:Vienna Convention road sign Aa-30-V1-1.svg|thumb|120px|left|Vienna Convention low flying aircraft (White triangle)]]

A warning sign with the image of an aircraft in the middle of it indicates an airport or airfield, where drivers should be prepared for low-flying aircraft.

=== Crosswinds or side winds ===
[[File:Vienna Convention road sign Aa-31-V1-3.svg|thumb|120px|right|Vienna Convention side winds sign (amber triangle)]]

Flying socks, as indicated in Poland by a [[windsock]] on red triangle or yellow diamond signs, indicate locations where a strong side wind may cause the trajectory of the moving vehicle to change drastically, perhaps even "flying" across lanes, causing an accident.

=== Roads with one entry point ===
[[File:British Columbia G-075.svg|thumb|120px|right|Canada: pictorial no exit sign]]

Roadways that only have one entry/exit point - "[[cul-de-sac|dead end]]", "not a through street" or "no outlet".

=== End of roadway ===
[[File:NYCDOT W14-5.SVG|thumb|120px|left|U.S. (New York City): roadway ends.]]
Signs indicating the end point of a [[roadway]].

=== Fire stations ===
[[File:MUTCD-TX W11-12T.svg|thumb|120px|left|Texas emergency vehicles sign]]

These signs warn of approach to where [[firefighter]]s may be entering the road with [[fire apparatus|fire engines]] or other emergency apparatus, where other drivers will have to stop and wait until they pass.

== Traffic warning signs with lights ==
Some warning signs have flashing lights to alert drivers of conditions ahead or remind drivers to slow down. In [[UK|Britain]], they are called ''warning lights''. Flashing lights can be dangerous for people with certain forms of [[epilepsy]] and/or [[sensory processing disorder]].

<gallery widths="160px" heights="160px" class="center" caption="Attached lights">
File:Skoleskilt.jpg|School zone traffic warning sign in Denmark
File:A17 lumineux.jpg|A traffic signal ahead sign in France (The light flashes to indicate a red light ahead.)
File:Photelectric lighted walk sign.jpg|A pedestrian crossing sign in the United States with solar-powered lit outline
File:Skiltetrailer højre.jpg|A portable multipurpose traffic warning array in Denmark, displaying {{lang|da|Ulykke}} ("accident") and "keep right"
File:SchoolZone-SpeedLimitSignAndLight.JPG|A school zone sign in the United States. When the light flashes, the set speed limit (in this case, {{Convert|25|mph|km/h|abbr=on}}) is active.
File:FEMA - 7349 - Photograph by Bob McMillan taken on 07-04-2002 in Texas.jpg|A "Watch for Water on Road" sign in the United States
</gallery>

== See also ==
{{div col|colwidth=23em}}
* [[Traffic sign]]
* [[Hazard symbol]]
* [[Comparison of European road signs]]
* [[Comparison of traffic signs in English-speaking countries]]
* [[Direction, position, or indication sign]] - Traffic signs that indicate directions, routes.
* [[Glossary of road transport terms]]
* [[Mandatory sign]] - Traffic signs that inform of required actions.
* [[One-way traffic]]
* [[Prohibitory traffic sign|Prohibitory sign]] - Traffic signs that inform of prohibited actions.
* [[Regulatory sign]] - Traffic signs that inform of traffic regulations.
* [[Road signs in Canada]]
* [[Road signs in the United States]]
* [[Variable-message sign]]
{{div col end}}

== References ==
{{Reflist}}

== External links ==
* {{Commons category-inline|Warning signs}}

{{Traffic signs}}

{{DEFAULTSORT:Warning Sign}}
[[Category:Traffic signs]]
[[Category:Signage]]
[[Category:Safety]]
[[Category:Warning systems|Signs]]