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A traffic warning sign is a type of traffic sign that indicates a hazard ahead on the road.

In most countries outside of North America, they often take the shape of an equilateral triangle with a thick red border and a white or yellow background.

In the People's Republic of China, however, they appear with a black border and a yellow background. In Sweden, Serbia, Bosnia and Herzegovina, Croatia, Greece, Finland, Iceland, the Republic of Macedonia and Poland they have a red border with an amber background. This is due to the weather, as it is easier to see a red/amber sign in the snowy weather then a red/white sign. The polar bear warning sign on Svalbard recently changed from displaying a black bear on white background to a white bear on black background (both sign are/were triangular with a red border).

In the United States, Canada, Mexico, Thailand, Australia, Japan, Philippines, and Malaysia warning signs are black on yellow and usually diamond-shaped, and construction signs are black on orange. Ireland also adopted these standards, diverging from the standards of the rest of Europe. Some other countries also use these standards for some signage.

Warning signs in different shapes:

Divider Begins Ahead	Railroad Crossing Sign	Rectangular shape	Diamond-shaped sign
Triangular with orange-yellow background	Triangular with yellow background	Triangular with white background

Contents 1 Warning signs 1.1 General Caution 1.2 Obstacles 1.3 Things Near or Crossing the Roadway 1.4 Road works or construction 1.5 Chevron Arrows 1.6 Tunnels 1.7 Bridges 1.8 Traffic Lights 1.9 Warning Signs for Regulatory Signs 1.10 Level Crossings and Intersections 1.11 Lane Starts/ends 1.12 No Passing Zone 1.13 Pedestrians 1.14 Schools 1.15 Fire stations 1.16 Oncoming Traffic 1.17 Level crossing/Railway crossing 1.18 Falling Rocks 1.19 The Unexpected 1.20 Road conditions 1.21 Side Wind 1.22 Slow Down 1.23 Merge To Stay With Through Traffic 1.24 ☡ 2 Warning Signs with lights 3 Evacuation Routes 4 Warning signs at other sites 5 See also 6 Notes

Warning signs can indicate any potential hazard, such as:

Non-specific warning to pay attention, the word "Caution," often for ambiguous reasons.

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.

Warns 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. Also equipment (tractors, forklifts, snowmobiles, golf carts, bicycles) crossing or traveling along the road. In the United States, a SHARE THE ROAD plaque is sometimes placed below these warning signs when used in this manner.

Indicates 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 don't actually mean that there is a flooded section of road ahead)

Used to indicate unexpected bends in the road, some being continuous, others being sharp-ended (right-angle turns). Left curve, right curve, series of curves. May also indicate direction of intersections along the upcoming curve. Also used to indicate "merge" with other traffic, as for an on-ramp of a limited-access highway.

Examples of junction warning signs used in the Republic of Ireland at bends and corners:

Arrow turning 90 degrees Dangerous corner	Curved arrow Dangerous bend	Zig-zag arrow Series of dangerous corners	Squiggle arrow Series of dangerous bends
T with one thin arm Junction at corner	Y with one thin arm Junction at a bend

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.

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 or floating bridge). Also used for underpass to indicate low overhead clearance.

Used to indicate traffic lights, present when it is difficult to see that a traffic light may already be showing red, to warn a driver to prepare to slow down. May be supplemented with flashing light or lighted sign when light is red or turning red.

As for traffic signals, above, some "stop" or "yield" signs may require additional warning or reminder, especially in dense areas or where the sign has been added recently.

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

Examples of junction warning signs used in the Republic of Ireland:

Cross with heavy horizontal line Crossroads with a major road	Sideways T with heavy vertical line Junction with a minor side-road	Line with a branch either side, staggered Staggered crossroads with roads of equal importance	T with one thin arm Junction at corner with a minor road
Line intersecting parallel bold lines Junction with dual-carriageway	Three arrows following each other in a circle Roundabout ahead

Indicates when a multilane highway is being narrowed, a passing lane is ending, or where the road is widening or a passing lane starting. Another type 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. Also used for "dead end", "not a through street" or "no outlet" roadways.

American "No Outlet" sign

British "end of dual carriageway" sign

Vertical yellow sign in triangular shape (in U.S.) to supplement solid yellow lane stripe where it is dangerous to overtake another vehicle, especially where roadway may be obscured by snow or other precipitation.

Used to warn drivers of people walking in the street. Also 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, there are warning signs showing a running family. This is to warn motorists to look out for illegal immigrants who try to escape authorities by running through freeway traffic.^[1]

For school zones (slow down), student crossings (pointed at top), crossing guards or signals ahead.

Warning upon approach to where firefighters may be entering the road with fire engines or other emergency apparatus, where other drivers will have to stop and wait until they pass.

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.

Used to warn people 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. These pictograms are also used in Ireland albeit on an amber diamond sign. In the United States the actual crossing is marked with crossed "Railroad Crossing" sawbuck signs (Stop, look, listen) and possibly lights, bells, and barriers.

Examples of level crossing warning signs used in the U.S. and Ireland:

X with RR in it Railroad crossing (U.S.)

X with train tracks across Unguarded level crossing (IRL)

Section of fence Level crossing with gates (IRL)

Level crossing signals with train passing Automatic level crossing (IRL)

Used to indicate the hazards of fallen or falling rocks on the road ahead. May be words or pictographs. May be "Fallen rock", "falling rock", or "rock slide" areas posted as such. In Italy the words may be "caduta sassi" or "caduta massi". In France "chûte des pierres". In Mexico "derrumbes", which is also a classification for the potency of certain magic mushrooms from Oaxaca.

British "falling rocks" warning sign.

Sign in Bowen Island, Canada.

For example, 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.

General dangers are signalled by placing a black exclamation mark in the middle of the red triangle.

"Slippery when wet", "grooved pavement" (warning to motorcyclists and bicyclists), "Open joints on bridge", "Icy Road", "Bridge freezes before roadway" and variants thereof, and "bump" or "dip" ahead (not related to construction). 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., 5 percent). Steep hills may also feature "Runaway truck escape" or :Emergency stop" areas with corresponding signs. The UK has a sign warning of "Adverse camber" on a curve. Also "Loose gravel", "Soft shoulder", "Speed hump", and "Watch for Ice."

U.S. "Slippery When Wet" sign

Steep grade sign

Flying socks, as indicated 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.

Used at least in U.S. and China, this sign advises drivers to slow

In the United States, 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, "Thru 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.

The Unicode character ☡ (U+2621) means "Caution sign". It is in the Miscellaneous Symbols plane.

Some warning signs have flashing lights to alert drivers of conditions ahead or remind drivers to slow down. In Britain, they are called warning light.

Some areas have special evacuation route signs that are to be followed in case of certain disasters. The signs point to routes either to safety or to less danger.

Evacuation signs are common in areas where there is a high risk of dangers such as flash flooding, volcanic activity and lahar, tsunami, hurricane and storm surge.

Warning signs are also found on other potential dangerous sites. At the base of electricity pylons or fences of substations or radiotechnical equipment with open parts leading high voltage, there are always warning signs, warning of the high voltage. Other warning signs can be found at the top of inclines. An also very common warning sign is a sign warning of feared dogs. The design of this sign can vary.

• Hazard symbol

v • d • e Traffic Signs
Signs	Warning sign • Regulatory sign • Priority to the right • Yield sign • Stop sign • Prohibitory traffic sign • One-way traffic • Speed limit • Advisory speed limit • Mandatory sign • Special regulation sign • Informative sign • Information, facilities, or service sign • Direction, position, or indication sign • Additional panels
By country	Iceland • Ireland • Malaysia • Norway • Singapore • Sweden • United Kingdom (Scotland)
Lights	Traffic light • Variable-message sign
Typefaces	Clearview • DIN 1451 • FHWA Series • Frutiger • NPS Rawlinson Roadway • Transport • Tratex
Conventions	Vienna Convention on Road Traffic • Vienna Convention on Road Signs and Signals • Manual on Uniform Traffic Control Devices