The sign is commonly referred to as a radioactivity warning sign, but it is actually a warning sign of ionizing radiation. Ionizing radiation is a much broader category than radioactivity alone, as many non-radioactive sources also emit potentially dangerous levels of ionizing radiation. This includes x-ray apparatus, radiotherapy linear accelerators, and particle accelerators. Non-ionizing radiation can also reach potentially dangerous levels, but this warning sign is different from the trefoil ionizing radiation warning symbol.[15] The sign is not to be confused with the fallout shelter identification sign introduced by the Office of Civil Defense in 1961. This was originally intended to be the same as the radiation hazard symbol but was changed to a slightly different symbol because shelters are a place of safety, not of hazard.[10][16]

Bicycles can be detected at newer traffic signals, but it relies on iron-based metal to trigger the signals. If your bicycle is made of carbon-fibre, fibreglass, plastic or aluminium it may not be detected.

The symbol, or some variation thereof, specifically with the bones (or swords) below the skull, was also featured on the Jolly Roger, the traditional flag of European and American seagoing pirates. It is also part of the Canadian WHMIS home symbols placed on containers to warn that the contents are poisonous.

The symbol was adopted as a standard in the US by ANSI in 1969.[10][12] It was first documented as an international symbol in 1963 in International Organization for Standardization (ISO) recommendation R.361.[13] In 1974, after approval by national standards bodies, the symbol became an international standard as ISO 361 Basic ionizing radiation symbol.[14] The standard specifies the shape, proportions, application and restrictions on the use of the symbol. It may be used to signify the actual or potential presence of ionizing radiation. It is not used for non-ionizing electromagnetic waves or sound waves. The standard does not specify the radiation levels at which it is to be used.[14]

If you think your car is not triggering the signals to change, there may be a fault with the detector. When this happens the signal automatically switches from detection mode to timed mode. Timed mode may not be the best way to deal with a range of traffic volumes, but it does allow safe signal operation until the fault can be repaired. These faults are automatically detected.

The international radiation symbol is a trefoil around a small central circle representing radiation from an atom. It first appeared in 1946 at the University of California, Berkeley Radiation Laboratory.[8] At the time, it was rendered as magenta, and was set on a blue background. The shade of magenta used (Martin Senour Roman Violet No. 2225) was chosen because it was expensive and less likely to be used on other signs.[9] However, a blue background for other signs started to be used extensively. Blue was typically used on information signs and the color tended to fade with weathering. This resulted in the background being changed on the radiation hazard sign.[10] The original version used in the United States is magenta against a yellow background, and it is drawn with a central circle of radius R, an internal radius of 1.5R and an external radius of 5R for the blades, which are separated from each other by 60°. The trefoil is black in the international version, which is also used in the United States.[11]

Queensland driver test

The biohazard symbol is used in the labeling of biological materials that carry a significant health risk, including viral and bacteriological samples, including infected dressings and used hypodermic needles (see sharps waste).[20]

An ‘all red’ light then applies on all roads following the yellow signal. This allows vehicles to move through the intersection before more traffic movements begin. This ‘all red’ time depends on the size of the intersection as larger intersections require longer clearance time.

On roadside warning signs, an exclamation mark is often used to draw attention to a generic warning of danger, hazards, and the unexpected. In Europe and elsewhere in the world (except North America and Australia), this type of sign is used if there are no more-specific signs to denote a particular hazard.[6][7] When used for traffic signs, it is accompanied by a supplementary sign describing the hazard, usually mounted under the exclamation mark.

A side road is joining the continuing road sign

According to Baldwin, who was assigned by Dow to its development: "We wanted something that was memorable but meaningless, so we could educate people as to what it means." In an article in Science in 1967, the symbol was presented as the new standard for all biological hazards ("biohazards"). The article explained that over 40 symbols were drawn up by Dow's artists, and all of the symbols investigated had to meet a number of criteria: "(i) striking in form in order to draw immediate attention; (ii) unique and unambiguous, in order not to be confused with symbols used for other purposes; (iii) quickly recognizable and easily recalled; (iv) easily stenciled; (v) symmetrical, in order to appear identical from all angles of approach; and (vi) acceptable to groups of varying ethnic backgrounds." The chosen scored the best on nationwide testing for uniqueness and memorability.[20]

The length of time for a green traffic signal depends on traffic conditions and should always appear for a minimum of six seconds. On most major roads with a speed limit up to 60 km/h the yellow or amber light is displayed for four seconds. For higher speed roads, more time is provided for the yellow or amber traffic light.

Hazard symbols are recognizable symbols designed to warn about hazardous or dangerous materials, locations, or objects, including electromagnetic fields, electric currents; harsh, toxic or unstable chemicals (acids, poisons, explosives); and radioactivity. The use of hazard symbols is often regulated by law and directed by standards organizations. Hazard symbols may appear with different colors, backgrounds, borders, and supplemental information in order to specify the type of hazard and the level of threat (for example, toxicity classes). Warning symbols are used in many places in place of or in addition to written warnings as they are quickly recognized (faster than reading a written warning) and more universally understood, as the same symbol can be recognized as having the same meaning to speakers of different languages.[citation needed]

In the United States, due to concerns that the skull-and-crossbones symbol's association with pirates might encourage children to play with toxic materials, the Mr. Yuk symbol is also used to denote poison.

The skull-and-crossbones symbol, consisting of a human skull and two bones crossed together behind the skull, is today generally used as a warning of danger of death, particularly in regard to poisonous substances.

The biohazard symbol was developed in 1966 by Charles Baldwin, an environmental-health engineer working for the Dow Chemical Company on their containment products.[21]

Traffic signals are controlled by a local computer at each intersection from which, information can be retrieved remotely. The Main Roads Transport Management Centre at Maroochydore can also access them.

This symbol has also been more widely adopted for generic use in many other contexts not associated with poisonous materials. It used for denoting number of dead victims caused by natural disasters (e.g. earthquakes) or armed conflicts on event infographics.

The United Nations has designed GHS hazard pictograms and GHS hazard statements to internationally harmonize chemical hazard warnings under the Globally Harmonized System of Classification and Labelling of Chemicals. These symbols have gradually replaced nation and region specific systems such as the European Union's Directive 67/548/EEC symbols,[28] Canada's Workplace Hazardous Materials Information System.[29] It has also been adopted in the United States for materials being sold and shipped by manufacturers, distributors and importers.[30] The USA previously did not mandate a specific system, instead allowing any system, provided it had met certain requirements.[31]

All other faults or problems with traffic signals should be reported to the Department of Transport and Main Roads Traffic Management Centre at any time day or night with a free call to 1800 678 501 or a local call to 13 19 40. This service is available 24 hours a day, 7 days a week.

This symbol has also been more widely adopted for generic use in many other contexts not associated with road traffic. It often appears on hazardous equipment, in instruction manuals to draw attention to a precaution, on tram/train blind spot warning stickers and on natural disaster (earthquake, tsunami, hurricane, volcanic eruption) preparedness posters/brochures—as an alternative when a more-specific warning symbol is not available.

Council controls more than 3,300km of roads, with over 25,000 intersections. Traffic signals are needed at intersections that carry large numbers of cars and people. They make it safer for road users such as cyclists and pedestrians. They cost less than roundabouts and do not take up as much space. Council installs new traffic signals each year that cost from $500,000 to over $5,000,000.

A chemical hazard symbol is a pictogram applied to containers and storage areas of dangerous chemical compounds to indicate the specific hazard, and thus the required precautions. There are several systems of labels, depending on the purpose, such as on the container for transportation, containers for end-use, or on a vehicle during transportation.

All parts of the biohazard sign can be drawn with a compass and straightedge. The basic outline of the symbol is a plain trefoil, which is three circles overlapping each other equally like in a triple Venn diagram with the overlapping parts erased. The diameter of the overlapping part is equal to half the radius of the three circles. Then three inner circles are drawn in with 2⁄3 radius of the original circles so that it is tangent to the outside three overlapping circles. A tiny circle in center has a diameter 1⁄2 of the radius of the three inner circles, and arcs are erased at 90°, 210°, and 330°. The arcs of the inner circles and the tiny circle are connected by a line. Finally, the ring under is drawn from the distance to the perimeter of the equilateral triangle that forms between the centers of the three intersecting circles. An outer circle of the ring under is drawn and finally enclosed with the arcs from the center of the inner circles with a shorter radius from the inner circles.[11]

Road sensors detect vehicles as they pass and either change signals to green or extend the green light time. At busy times, the green light period may extend to a set limit and the signals will follow a set sequence. Some signals respond to traffic arriving at the intersection.

You can use CTR+V to paste a screenshot from your clipboard directly into the textarea above. Otherwise you can upload a file from your computer below.

PrepL

The Workplace Hazardous Materials Information System, or WHMIS, is Canada's national workplace hazard communication standard, first introduced in 1988, and included eight chemical hazard symbols.[34] This system was brought into alignment with GHS in 2015, with a gradual phase in of GHS symbols and label designs through 15 December 2025.[29] The WHMIS system does deviate from GHS by retaining the former WHMIS symbol for Class 3, Division 3, biohazardous infectious materials, as GHS lacks a biological hazard symbol.[29]

Some warning symbols have been redesigned to be more comprehensible to children, such as the Mr. Ouch (depicting an electricity danger as a snarling, spiky creature) and Mr. Yuk (a green frowny face sticking its tongue out, to represent poison) designs in the United States.

On February 15, 2007, two groups—the International Atomic Energy Agency (IAEA) and the International Organization for Standardization (ISO)—jointly announced the adoption of a new ionizing radiation warning symbol to supplement the traditional trefoil symbol. The new symbol, to be used on sealed radiation sources, is aimed at alerting anyone, anywhere to the danger of being close to a strong source of ionizing radiation.[17] It depicts, on a red background, a black trefoil with waves of radiation streaming from it, along with a black skull and crossbones, and a running figure with an arrow pointing away from the scene. The radiating trefoil suggests the presence of radiation, while the red background and the skull and crossbones warn of danger. The figure running away from the scene is meant to suggest taking action to avoid the labeled material. The new symbol is not intended to be generally visible, but rather to appear on internal components of devices that house radiation sources so that if anybody attempts to disassemble such devices they will see an explicit warning not to proceed any further.[18][19]

Please note, you do not need to get all the way across the road while the walk signal is on. The walk signal is used to inform people when they can start to cross but the flashing don't walk signals allow enough time to cross the road safely.

Simply leave your comments below. If the feedback is about a bug, please provide the steps you took so we can replicate.

The US-based National Fire Protection Association (NFPA) has a standard NFPA 704 using a diamond with four colored sections each with a number indicating severity 0–4 (0 for no hazard, 4 indicates a severe hazard).[35] The system was developed in the early 1960s, as a means to warn firefighters of possible dangers posed by storage tanks filled with chemicals. The red section denotes flammability. The blue section denotes health risks. Yellow represents reactivity (tendency to explode). The white section denotes special hazard information, not properly covered by the other categories, such as water reactivity, oxidizers, and asphyxiant gases.[35]

The most common traffic signal fault reported to council is faulty lights/lamps. The computer at each set of traffic signals sends fault messages to repair electricians to attend to the fault as soon as practically possible.

Council controls more than 25,000 intersections. Traffic signals are used to improve pedestrian, cyclist and driver safety at significant intersections

Tape with yellow and black diagonal stripes is commonly used as a generic hazard warning. This can be in the form of barricade tape, or as a self-adhesive tape for marking floor areas and the like. In some regions (for instance the UK)[5] yellow tape is buried a certain distance above buried electrical cables to warn future groundworkers of the hazard.

The European Union aligned its regulations with the GHS standards in 2008 with the adoption of CLP Regulation, replacing its existing Directive 67/548/EEC symbols during the mid-2010s, and requiring use of GHS symbols after 1 June 2017.[32][33] Since 2015, European standards are set by:

Council controls more than 100 sets of traffic signals on the Sunshine Coast. The Department of Main Roads controls traffic signals on some major Coast roads such as Nicklin Way, Caloundra Road and Maroochydore Road.

An important safety feature of traffic signals is that anyone approaching an intersection will see a minimum of three sets of traffic lights. If one or two traffic lights are out, the driver is still able to see a working set of traffic lights. The likelihood of all three traffic signals failing at once is very low. If one or two traffic signals are not working, there is no need to report this to council as the default has been detected by the computer and the repair electricians will already be planning to replace the bulb as part of their regular maintenance schedule.