Emergency vehicle lighting
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Emergency vehicle lighting refers to any of several visual warning lights fitted to a vehicle and used when the driver wishes to convey to other road users the urgency of their journey, to provide additional warning of a hazard when stationary, or in the case of law enforcement as a means of signalling another driver to stop for interaction with an officer. These lights may be dedicated emergency lights, such as a beacon or a light bar, or may be modified stock lighting, such as a wig-wag or hide-away light, and are additional to any standard lighting on the car such as hazard lights. Often, they are used along with a siren (or occasionally sirens) in order to increase their effectiveness. In many jurisdictions, the use of these lights may afford the user specific legal powers, and may place requirements on other road users to behave differently, such as compelling them to pull to the side of the road and yield right of way so the emergency vehicle may proceed through unimpeded.
Laws regarding and restricting the use of these lights vary widely between jurisdictions, and in some areas non-emergency vehicles (e.g. school buses) and semi-emergency vehicles (e.g. tow trucks) may be permitted to use similar lights. These non-and semi-emergency lights are also discussed here. Research into the usefulness and potential dangers of these lights is also presented.
Emergency vehicle lighting is a subtype of emergency vehicle equipment.
Emergency vehicle lighting is generally used to clear the right of way for emergency vehicles, or to warn approaching motorists of potential hazards, such as a vehicle that is stopped or moving slower than the rate of traffic, or a car that has been pulled over. It may also be used to provide specific directions to motorists, such as a command to pull over. Some vehicles incorporate a small arrow board to direct traffic.
The use of emergency beacons is restricted by law in many jurisdictions only for responding to an emergency, initiating a traffic stop, bona fide training exercises, or when a specific hazard exists in the road. Most private security agencies have special permits that allow them to use beacons in specific areas.
The optical and mechanical characteristics of the lights used can have a significant effect on the look of the vehicle and how readily it gains attention in emergencies.
The simplest form of lighting is a steadily burning lamp. These may be white lights used on scene to enable emergency workers to see what they are doing, or they may be colored lights that advertise the emergency vehicle's presence. In the latter case, steadily burning lights are often used alongside rotating or flashing lights rather than on their own, though historically some emergency vehicles only displayed steadily burning lights. For example, California Vehicle Code Section 25252 states that: "Every authorized emergency vehicle shall be equipped with at least one steady burning red warning lamp visible from at least 1,000 feet to the front of the vehicle"
These revolving lights may contain a single, stationary bulb around which a curved mirror is spun (or which is attached to a spinning mirror), or a lamp with a Fresnel lens. This creates rotating beam(s) of light, appearing to flash when viewed. Larger rotating lights may contain modular or sealed-beam lamps which rotate as an assembly (commonly 2 or 4 bulbs, but possibly 1 or 3).
To protect the workings of the beacon, a plastic dome often covers the assembly. These domes usually come in solid colors, but in some cases the front and back halves of the dome are different colors. Other beacons use a clear dome with colored lenses on each lamp. Especially in the last case, these rotating beacons are sometimes referred to colloquially as "gumball machines" or sometimes "cherry tops" in the case of red lights.
Rotating lights may be used in lightbars as well as in single beacons. In a modern enclosed lightbar, generally 'V'- or diamond-shaped mirrors are provided between the lamps to give the effect of multiple flashing lights.
Some emergency lighting is based on strobe lights similar to those used in flash photography. These xenon flash lamps put out a very brief but very bright flash by ionizing and then discharging a large current through the gas. The light produced has a somewhat bluish emission spectrum, which makes red lightbars glow a fuchsia-pink color when lit.
LED-based lighting is becoming very popular in the emergency services for several reasons. Light-emitting diodes are small, completely solid state, very power-efficient, long-lasting (as they have no filaments to burn out) and can be seen very easily even at great distances and in sunlight.
Whether as lightbars or single beacons, LED-based lights typically use a clear, colorless dome because the light color is an intrinsic property of the LEDs themselves. LED-based lightbars can be made very thin, reducing wind resistance by around 8-10 percent, or made very flat and used in novel applications, for example to flip up under a sun visor.
LED lights are often used in a mode similar to conventional strobe lights, however they can be programmed with a wider variety of flash patterns because of their ability to be switched directly by electronics, as opposed to discharging a capacitor through a gas-filled tube.
LED lights produce relatively little heat when in use. In colder inclement climates, this has resulted in LED emergency vehicle warning lights (as well as traffic lights) being obscured by the buildup of frost or snow, raising safety concerns. Solutions are being researched to provide a heat source, as necessary in certain weather conditions, to keep LED lights clear of snow and frost.
Modification of stock lighting
The vehicle's stock lighting may also be modified to add flashing and strobe effects. This can be done by adding electronics to the existing lighting system (for instance, to create a wig-wag), or by drilling holes in the reflectors of stock lighting and inserting flashing lights in those holes.
Information matrix signs
Some emergency vehicles use signs made up of a large number of light sources (usually LEDs), which can be programmed to display messages to other road users. This can be used to request other vehicles to pull over, indicate a special instruction, or just to display the name of the operating service (e.g. 'Police')
Emergency lighting may be fitted to several places on a vehicle, depending on the degree of conspicuity required. Beacons and lightbars are often mounted on the roof for high visibility, while other lights may be mounted on the body, in the grill, or in the interior of the vehicle.
Roof-mounted single beacon
Since their introduction in 1948, rotating beacons have become widely accepted as a means of attracting attention to one's vehicle. Although the use of the single beacon in law enforcement has dropped since the introduction of light bars, they are still used by some police departments, because of their lower cost or due to tradition. One agency that continues to employ traditional red rotating beacons on its patrol cars is the Michigan State Police. Beacons are also occasionally used on construction equipment when a full-sized lightbar would be unnecessary or impractical to attach to the vehicle.
While many single beacons use rotating lamps or mirrors, others use strobe lights under a translucent dome to provide an omnidirectional flash. Some smaller and low-cost beacons of the latter type, however, are simply a blinking incandescent bulb. LEDs are also used to light some omnidirectional beacons.
The single beacon is also available with a magnetic mount for situations where permanent mounting is impractical. Examples of such situations would be detectives in unmarked vehicles, volunteer firefighters, or managers at freight yards who use an amber light for safety. These "mag-mount" beacons are often round or teardrop-shaped, and are often referred to as "Kojak" lights after the popular 1970s TV detective who used one.
Originally, this referred to a simple metal bar on the roof of the vehicle upon which agencies would mount two rotating beacons, as well as other components such as sirens and stationary "lollipop" lights. Soon the beacon manufacturers began producing off-the-shelf complete "light bars".
Later, the individual components of the lightbar were integrated into a single contiguous unit, with two elongated domes on either side of a siren enclosure. The extended domes allowed for more rotating beacons, additional mirrors, and fixed-beam lights toward the center to replace the "lollipops".
Lightbars may now contain fixed, rotating, strobe, or LED-based lights in various configurations and offering programmable flash patterns. They may include a second, lower, tier of lamps, such as clear halogen "takedown" lights towards the front to illuminate the vehicle being stopped, clear side-facing "alley" spotlights, additional amber or red towards the rear for scene protection, or directional traffic advisory arrows. The modern trend of locating sirens on or near the front bumper of emergency vehicles has resulted in many lightbar models eliminating the siren housing in lieu of more lighting.
Some lightbar variations are specialized to meet certain desires of the agencies utilizing them, such as those using multiple rotating beacons in a "V" pattern to provide additional illumination to the sides of the vehicle, and those designed to hug the roof of a vehicle to minimize air resistance or present a lower profile for "stealth" purposes.
Some types of light can be mounted on to the outside of the vehicle (usually a permanent install) and these can be used to provide directional lighting in key areas, such as in front for clearing traffic, or to the rear for scene protection. They can also form part of the main lighting arrangement for subtly marked or unmarked vehicles. In this application, the operating service may choose to use lights with clear lenses so as to minimize the possibility of the lights being noticed when not on.
Common places to mount such beacons include on or in the grill of the vehicle and on the front of the rear view mirrors, where they can gain maximum visibility. In the UK many emergency vehicles have lights on the side of the bonnet, which helps to warn oncoming traffic when pulling out of junctions. These lights are often strobe or LED types, as they have the lowest profile for purposes of attachment.
Sometimes, the existing lighting on a vehicle is modified to create warning beacons. In the case of wig-wag lighting, this involves adding a device to alternately flash the high-beam headlights, or, in some countries, the rear fog lights. It can also involve drilling out other lights on the vehicle to add "hideaway" or "corner strobes".
A variety of emergency lights may be used in the interior of a vehicle, generally on the dashboard, visor area, or rear deck. Uses range from discreet or temporary lighting for unmarked vehicles and volunteer responders, to additional rear lighting on fully marked vehicles, to a "slick-top" configuration not unlike a full lightbar set.
Interior lighting is available in a variety of form factors, ranging from flat LED panels under the sun visors, to halogen or strobe lights mounted on the rear deck, to "cherry" or oscillating "teardrop" lights mounted on the dash. These may be permanently mounted and wired into the vehicle's electrical system, or they may be temporarily mounted and plug into the vehicle's cigarette lighter. They are often fitted with shields which direct the light through the window, but prevent reflections in to the cab.
The aerodynamic properties of light bars can be important for police applications, as fuel efficiency and drag are concerns in patrol and pursuit. Because of this, some police cars do not have roof mounted lightbars. These "slick-top" cars mount their emergency lights within the cruiser, generally around the periphery of the windshield or into the leading or trailing edge of the roof. Slick-top police cars also lack the silhouette of a lightbar or beacon, making the car harder to identify as a police vehicle from a distance, especially fore and aft. Because of these visual advantages, these vehicles are sometimes referred to as "stealth" vehicles.
A key disadvantage of relying solely on internal lighting is the number of lights required to achieve true 360 degree visibility, with most lights usually concentrated front and rear. This can limit the application of vehicles for instances such as scene protection.
A study at Loughborough University in the United Kingdom showed that strobe lighting conveyed a greater sense of urgency to other road users, with the faster the flash the greater urgency, potentially helping to speed the emergency vehicle through traffic. It also concluded that factors such as flash pattern were important, with simultaneously flashing beacons attracting attention far quicker than alternately flashing versions, although this did increase discomfort glare. Unsurprisingly, attention was gained far quicker the higher the intensity of the light was, and the more beacons were present.
This same study compared different light colors for glare and detection time under both daylight and night conditions. While red and blue both compared favorably with amber for glare under various conditions, some contradictory findings were observed for detection time. When all colors were held at equal intensity, amber had the poorest detection time both daytime and night. But when the light source was held at constant intensity, the amber filters, which generally let the most light through, had the best detection time.
There may be a number of hazards to other road users related to the use of emergency beacons, and these effects should be mitigated as far as possible during vehicle design. These potential hazards include:
- Photosensitive epilepsy - This is an epileptic reaction to flashing lights in susceptible persons, which can range in severity from an unusual feeling or involuntary twitch to a generalized seizure. This epileptogenic response can be triggered by lights flashing in the frequency range of 10–20 Hz, regardless of color. While individual light sources used on emergency vehicles generally have much lower flash rates than this, the Loughborough study suggests that such possibilities be minimized. It also notes that emergency workers may report distraction and eyestrain unrelated to epilepsy from working under the lights.
- Glare - A bright light source in a person's field of view can reduce their ability to see other objects. The effect may be exacerbated by rain, windshields, or eyeglasses. The study distinguished between "disability glare", where a driver may be temporarily blinded and unable to see hazards in the road, versus "discomfort glare", which is a more general effect from lights which may cause motorists to avert their eyes. The worst effects for disability glare occurred with amber beacons, strobe beacons, and especially bright lights.
- Phototaxis - This is the so-called 'moth-to-flame' effect, where the hypothesis runs that some drivers may be so distracted by the beacons that they are 'drawn' to them. The Loughborough study, referencing the February 1998 issue of the U.S. trade journal Tow Times, asserts that there was a lawsuit in the U.S. where a tow operator was found liable for an accident for this reason, though the study authors were unable to locate any supporting scientific research.
Usage by country
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The color of a vehicle's emergency lights is useful to denote the type of vehicle or situation, but the relationship between color and service varies widely by jurisdiction. In North America the usual emergency colors are red and blue, with blue generally reserved for police in many jurisdictions and red reserved for fire departments and emergency medical services. In western Europe the emergency color tends to be only blue, with amber as a warning color for construction equipment, etc. In eastern Europe emergency vehicles use blue, or a combination of blue and red. In Asia the usual emergency color is red.
By far the most common colors for the core emergency services to use are blue and red, and there are some arguments for using both. One study found that for flashing lights, red was more easily perceived in daylight, and blue at night. Furthermore, red has advantages in haze and fog, while blue stands out against traffic at night. On the other hand, a different study found that red had the quickest detection times at night.
Argentina uses blue for police, red with some blue for fire, green for ambulances, and amber for utility vehicles.
In Australia, colors are generally regulated at the state level, but there are some commonalities:
- Red and Blue is used by all State and Federal Police forces, Military Police, Australian Customs as 'law enforcement' vehicles. Red and blue is also used by all State and Australian Defence Force fire and ambulance services. Civilian Ambulance and most fire units across the country use red and blue lights with State Emergency Service vehicles in most states being authorised to use the red and blue light combination (except for Queensland and WA SES ). New South Wales also allows red and blue to be used by Roads and Traffic Authority traffic commanders and traffic response crews designated as emergency vehicles.
- Red signifies a risk-to-life situation, and is used alone by Mines Rescue, Red Cross blood/organ transport and St John Ambulance Service. Until recently some states used only red on fire engines, ambulances and State Emergency Service vehicles.
- Amber lights are used by tow trucks, road construction/repair vehicles and most other utility vehicles. Amber is also used by vehicles operating in and around airports and docks, this includes Australian Federal Police and Australian Customs vehicles which are fitted with additional amber lighting to supplement their red and blue lightbars. Queensland State Emergency Service vehicles are only authorised to display amber lights under certain circumstances.
- Green lights are used to denote a stationary ambulance, fire or police command vehicle. In Queensland it is also used on some State Forest bush fire units along with the amber. Further, in Queensland, some municipal animal control units use a green and amber light combination.
- Blue lights are reserved for emergency vehicles in general, such as police, fire, ambulance, State Emergency Service (except Queensland) and traffic commanders. Blue by itself is also used by airport emergency vehicles to designate a command vehicle.
- Magenta (purple) lights are primarily used by heavy vehicle enforcement/escort officers of the New South Wales Roads and Traffic Authority, Victorian VicRoads and South Australian Transport Safety Inspectors. They are also used in combination with amber lights by some council rangers and the New South Wales Ministry of Transport. In Western Australia magenta is used by the Department Of Environment and Conservation "HAZMAT Response Unit". Magenta is also used in some Escort Vehicles used whilst escorting large mining equipment to the north of the state.
- White is used on most newer emergency vehicles, both as an extra color on lightbars and in the form of 'wig-wag' headlights.
Many police vehicles, and less often other emergency services, also fit LED matrix variable message displays to vehicle lightbars. Such message bars used in New South Wales by the police and fire brigade are capable of displaying numerous messages warning motorists of various hazards or dangers.
Generally, red is used for emergency vehicles, amber for construction and utility vehicles, and green for volunteer firefighters. Blue is used, along with red, for police, as well as for snow removal vehicles in Ontario (with Amber for Municipal snow removal) and purple is used for a funeral. Police now use both red and blue Canada-wide(except where local laws prohibit), including Ontario (thanks to successful testing in Toronto and Ottawa, and changes in the provincial traffic act), where the color blue was only used for non-emergency work. Blue flashing lights are still permitted on snow removal vehicles in Ontario, as long as they are not used in conjunction with flashing red lights. 
Some provinces restrict municipal peace officers (the exact title varies by province) to a different color; for instance, red-only in Québec, and amber in Ontario. However, Ontario does permit certain types of provincial enforcement officers, such as Ministry of Transportation, red lights. Officers appointed to enforce the Highway Traffic Act and other statutes use red or red and blue lights as well, such as Ministry of the Environment, Ministry of Natural Resources, University Constables and others. White flashing lights are common as a supplemental light on emergency vehicles, particularly for fire and ambulance vehicles.
In some provinces, green may indicate a volunteer firefighter's medical responder's private vehicle, or other volunteer emergency first responders such as Search and Rescue personnel, In New Brunswick Green is reserved for EMO Command post. In addition to the use of optional green lights, volunteer firefighters often receive special licence plate size markings (red letters on a yellow background) to be displayed in place of a front licence plate, or in the window of said vehicle.
Utility vehicles generally use amber. Ontario and Newfoundland use blue lights for snowplows, while Alberta uses amber and red for snowplows, and has a public awareness campaign advising motorists that "flashing amber and red means snowplow ahead". Alberta also allows red lights on certain classes of utility vehicles, such as natural gas utilities which may need to disconnect a gas line in an emergency.
While funeral vehicles may also use amber, more recently, some funeral vehicles in Ontario, and more recently Alberta; have begun using purple lights for identification. Often, as a courtesy, motorists yield to funeral processions. However, they are not required to by law.
- Red and Blue: police; and other "non-police" law enforcement in all provinces and territories.
- Red: fire department, other "non-police" law enforcement in the provinces of ON and QC and search and rescue vehicles in BC.
- Red and White: Emergency Medical Services, St. John Ambulance and private ambulatory services; police services that have not changed over to Red and Blue
- Blue: snow plows (see below for Ontario), municipal and private contractors except BC.
- Amber and Blue: snow plows - Manitoba and Ontario (only on Municipal vehicles).
- Amber: construction and utility; funeral homes; airport service vehicles (excludes emergency vehicles); private snow removal vehicles (Ontario); Canadian Automobile Association Emergency Assistance vehicles; snow removal (Nova Scotia).
- Purple: funeral processions - British Columbia, Ontario, Alberta, Manitoba, Nova Scotia, and Prince Edward Island.
- Green: is now being used by security agencies. It is also being used by emergency service volunteers in certain provinces. Green may also be used by stopped Emergency Vehicles to denote a command vehicle or the site commander, New Brunswick EMO Command post.
- White/Clear: mall security (Ontario); university campus security (Ontario)
(Other "non-police" law enforcement means entities such as Conservation Officer, Environmental Officer, Provincial Officer, Ministry/Department of Transportation Enforcement Officers, University Constables, Community Peace Officers, and in some cases, Municipal By-law Enforcement Officers and Fuel Tax Enforcement Officers)
In most of Europe emergency vehicles use blue lights. However, it is a darker specification blue than used in other parts of the world. Swedish ambulances and fire engines often use white along with the dark "euro" blue to improve visibility during daylight hours.
In Spain, the law allows only the Cuerpo Nacional de Policía, Guardia Civil, Policía Local and autonomous law-enforcement agencies to use blue lights, so in contrast with convention in Europe, civil defence, ambulances (Ambulancia) and fire engines (Bomberos) have to use yellow/amber lights (the only other color authorized, in contrast to convention in which these color lights are used to denote slow vehicles). However some Autonomous Communities have allowed other colors, such as blue, red or white (the latter two of which is used by SAMUR in Madrid), which however, would be technically illegal to use throughout Spain. However, also yellow/amber lights are used in wide-load trucks and their accompanying vehicles.
In Germany, only emergency and police vehicle may use blue lights. This includes firefighters, rescue services, emergency response vehicles for public utilities and civil defense units. All other kinds of blue lights (e.g. car floor lighting or cab interior lights) are illegal on public roads. This shall ensure that emergency vehicles are easily recognisable. Flashing blue lights and sirens may only be used by authorised vehicles in case of emergency and order all other vehicles to make way, since these vehicles have the absolute right of way. Blue lights alone may be used to secure the site of an accident (or a standing emergency vehicle). Sometimes, columns of emergency or police vehicles use blue lights (without sirens) to make the column more visible to other vehicles.
German police lightbars often have "POLIZEI" written in white over the dome, and usually incorporate an LED text display that can read, in mirrored writing if towards the front, "STOP POLIZEI" or "BITTE FOLGEN" ("please follow"), to signal drivers to pull over. In the newest generation, the text display changes between German and English (STOP POLIZEI -> STOP POLICE and BITTE FOLGEN -> FOLLOW ME) British police lightbars use the word "STOP".
In the Netherlands, the color of emergency vehicle lighting is blue. Vehicles using flashing blue lights and siren have right of way over all other vehicles. Only designated emergency/priority vehicles may use blue lights; this includes police, fire brigade, ambulance service and a few other, smaller services such as the blood bank and some lifeguard organisations. Dutch police vehicles have an LED matrix display, which can show different texts in red lighting. Most often used are POLITIE STOP (ordering a driver to pull over and stop) or POLITIE VOLGEN (ordering driver to follow the police vehicle). Standard Dutch police cars often have the text bar incorporated in the light bar, vans and motorcycles usually have a separate sign on the front of the vehicle. On ambulances, a green beacon indicates the command vehicle when multiple units are responding to an incident - usually this is the first vehicle that arrives on the scene. Newer ambulance models also have a text display that will alternate the words "Ambulance" and "Spoed" (urgent).
Red lights are not as common in Europe, though they are used in some countries where red has a specific meaning. Police in Finland, Estonia, Germany and Sweden use a forward-facing red light to indicate that a driver must pull over and stop. Germany and Sweden also use red on fire vehicles to designate the command post; in other countries a single green beacon sometimes designates the command post. In Sweden, a green strobe will indicate a medical command vehicle. Greece uses red on fire engines, and red along with blue on police vehicles. In Poland, red is used on some police and military vehicles to show that it leads a convoy. Until recently the National Police in Slovakia used only blue lights, they have recently started using red and blue lights; Municipal and Military Police used blue lights in Slovakia.
Sweden also allows blue lights to be used on vehicles of "vital importance to the community". This means response vehicles from gas companies and electrical companies may use blue lights and sirens, vehicles use by railroad/tram/metro fast response units and vehicles of the Swedish Customs Service. Vehicles that transport blood or donor organs may also use blue lights and sirens. Cars carrying armed security officers (tasked with protecting embassies, airports and government buildings) may use blue lights and sirens if responding to an alarm.
In France police cars are only required to have blue, though amber is commonly used in conjunction with blue, but not alone.
In Latvia, mostly all the emergency vehicles are equipped with roof lightbars that are:
- white with white/dark blue colour with smaller EU dark blue lights - Police (Policija), Road police (Ceļu policija)
- dark blue with smaller white lights + dark blue beacons - Paramedics (Neatliekamā ātrā palīdzība)
The gas emergency service (Avārijas dienests/Gāzes avārijas dienests) and the firefighter cars are equipped with the dark blue beacons on top. The gas emergency service vehicles don't have lightbars. The Police cars are the only ones that have dark blue dash flashers.
In Romania three types of light are used: red, blue and amber. At a red rotating light, stopping (outside of the way) is compulsory, for a blue light slowing down and moving out of the wayis compulsory, and an amber light meens proceed with caution due to oversized or slow vehicle.
Cars that are allowed to use a blue rotating light are: Police (including Local Police), Gendarmerie, Border Police, Ambulance (including SMURD), Civil Protection, Ministry of National Defense, Special Units of the Romanian Intelligence Service, Protection and Guard Service, Ministry of Justice - General Directorate of Prisons, Public Ministry - when in mission, National Anticorruption Directorate - when in mission, and Financial Guard vehicles.
The amber rotating light means: oversized vehicle (and acompaning vehicles), overweight vehicle (and acompaning vehicles), daengerous transport, road/street maintenance, tow vehicles, tractors, agricultural vehicles.
In Norway military and civil defense vehicles may also use a blue flag or non-flashing light to mark the first vehicle in a group of four or more vehicles which has the right of way and a green flag or non-flashing light to mark the last vehicle of the group.
Usage of emergency vehicle lighting is restricted in the United Kingdom through the Road Vehicle Lighting Regulations 1989. It is illegal for any vehicle to show a flashing coloured light (with the exception of the normal direction indicators or a green anti-lock brake warning indicator), unless it is an emergency or other authorised vehicle. However recently pedal cycles can exhibit a flashing rear red lamp.
The main colour for emergency service vehicles is overwhelmingly blue, although there is also widespread use of flashing (white) headlights. The legal definition of an emergency vehicle limits the use of both methods to vehicles used for:
- Fire brigade, ambulance or police purposes (this includes private fire or emergency ambulance services, but not private security)
- Fire salvage
- Forestry Commission or local authority when fighting fires
- Ministry of Defence bomb disposal, mountain rescue, nuclear emergency or armament support, or special forces responding to a national security emergency
- National Blood Service or Scottish National Blood Transfusion Service vehicles
- HM Coastguard
- British Coal Corporation (now the Coal Authority) for mine rescue
- RNLI lifeboat launching vehicles (usually restricted to launching slipway)
- mountain rescue
- carrying human tissue for transplant
- HM Revenue and Customs when investigating serious crime.
Blue flashing lights must only be lit at the scene of an emergency, or when the driver considers it desirable to indicate that the journey being undertaken is urgent, and (in terms of the law) convey to other drivers that they should take special care.
Although not specifically linked to the use of warning beacons, the police, fire brigade and ambulance services (and in certain cases, the blood services and bomb disposal units, but not the other emergency services listed above) may also choose to allow their drivers to claim legal exemptions from certain motoring regulations, such as being able to treat a red traffic light as a give way sign, exceeding the speed limit, passing the wrong side of a keep left/right sign, driving in a bus lane, or parking in restricted areas. They may not, however, ignore "no entry" signs, drive the wrong way down a one-way street or cross a solid white line in the middle of the road (other than the same exceptions granted everyone else, for example to pass a stationary vehicle). In reality some drivers will disobey other laws at their professional judgement but they do so without any automatic protection from the law. Some services, such as HM coastguard do not allow all their staff to claim all the exemptions available to them.
No qualification other than a driver's license is legally required to use blue lights; whilst provision has been made to require the drivers of emergency vehicles to have suitable training if they will be driving above the speed limit, this has not yet been brought into force. However most organisations will insist that their drivers are trained in emergency driving techniques.
The common combination of blue flashing lights with two-tone sirens has led to 'blues and twos' becoming a nickname for the core emergency services as a whole, as well as the title of a British documentary series depicting them.
Amber lights grant no priority in traffic and exist purely to advertise the vehicle's presence. The Regulations specifies several classes of vehicles which may use amber lights, such as towing, highway maintenance, pilot vehicles escorting an oversize load, and vehicles unable to travel over 25 mph and fitting these lights to other vehicles(such as privately owned or pedestrian) is legal (these beacons are widely fitted to vehicles as wide ranging as security and ambulances).
Amber LEDs are widely used on operational appliances owned by Hampshire Fire and Rescue Service. The combination of blue and amber LEDs in a light bar are proven to be more visible at a distance. Amber lights are also utilised by the Vehicle and Operator Services Agency (VOSA)
Green emergency lighting is used by doctors on emergency calls, but it grants no privileges or exemptions from traffic laws.
Flashing red lights are not generally allowed on vehicles, though many emergency vehicles have rear-facing flashing red lights, which are used to signify that the vehicle is stationary. These are, however, specifically prohibited by the Regulations. Hazard lights may be wired to function at the same time, to make civilians further conscious of their presence. Fog lights may also be used in an alternating left/right pattern.
Steady chequered lights denote command and control vehicles - these are red and white for fire (one of the few situations where a forward-facing red light may be shown), blue and white for police and green and white for ambulance, and are often fitted in the middle of the light bar.
It should also be noted that UK legislation considers all lights, reflectors and reflective material to be lights, and all items resembling special warning beacons (of any colour) must be covered and not just disconnected (as this is a separate offence) while on the public highway. Similarly, no distinction is made between lights mounted on light bars and those mounted anywhere else on the vehicle (e.g. headlights, indicators, brake lights) - all are covered by the same regulations.
Under Hong Kong Law, Chapter 374G of the Road Traffic (Traffic Control) Regulations: Section 46 Giving way to animals, police vehicles, ambulances, etc., drivers must yield to vehicles who are sounding siren or flashing light bars.
- Red and Blue: Hong Kong Police Force
- Red only: Fire Services Department fire engines
- Blue only: Ambulances, whether operated by Fire Services Department, Auxiliary Medical Services, or Hong Kong St. John Ambulance, also Customs and Excise Department, Hong Kong Correctional Services
- Amber only: Utility vehicles, also Civil Aid Service, and all vehicles in the air-side of the airport (for pilots' visibility), Hong Kong Immigration Department vehicles
Red is the most used color on Japanese emergency vehicles, with the exception of the wig-wag headlights. The Japanese police uses light bars mounted on a raised platform or a mechanical raised platform to make them more visible over congested streets. Rotating light are the most commonly used. But some of the newer fire vehicles do have LED light bars installed. Vehicles with any other color light are security or engineers.
- Red: Police Department, Fire Department, and any other emergency vehicles.
- Amber: Engineer vehicles and Japan Highway Public Corporation vehicles.
- Blue: Security and City vehicles.
- Red: Used by any vehicle defined as an emergency vehicle to signify vehicles to give way to the emergency vehicle. This includes the New Zealand Fire Service, recognized ambulance services, and the New Zealand Police.
- Blue: Used by any vehicle that has statutory authority to signify a vehicle to pull over and stop. Used by the police, customs officers, fisheries officers, and marine reserve officers.
- Amber: Amber lights may be operated by towing companies, traffic management agencies, or by other utility vehicles when necessary to warn other motorists of a hazard. Amber must also be fitted to oversize vehicles and their pilot vehicles.
- Purple: Purple and amber lights must be fitted to pilot vehicles escorting an oversize vehicle.
- Green: Green emergency lighting is used by Registered Medical Practitioner, Registered Nurse or Registered Midwife on emergency calls, but it grants no privileges or exemptions from traffic laws 
Volunteers in general are afforded no special privileges and cannot use flashing lights or sirens in order to navigate traffic. However, volunteer Operational Support(ex Fire Police ) members who respond to calls in their own private vehicles may be authorized by their unit or brigade to display a red beacon, for reasons of safety and identification. However, these lights may only be fitted and operational while stationary at an emergency scene, not while mobile in traffic.
- Red: Fire department, ambulances of the Gyeongi province, some police vehicles
- Blue: Police motorcycles, some police vehicles, volunteer fire fighters
- Red and blue: Police patrol cars
- Green: Ambulances (some privately operated ambulances use the mix of green and red)
- Yellow/amber:Utility vehicles
In the United States, colors are generally regulated at the state and local levels, but there are some commonalities.
- Red almost always denotes an emergency vehicle if the lights are facing forward. In the state of Iowa, red lights can also be used on a funeral hearse, but only during funerals. In Washington State, red lights are also used on tow trucks, but only if the vehicle is not in motion. In Wisconsin, tow trucks are required to be equipped with red lights but such lights may be operated only when the tow truck is standing on or near the traveled portion of a highway preparatory to towing or servicing a disabled vehicle. A near universal exception to this rule is school buses which are allowed to use rear and forward facing, usually alternatively phased flashing red lights just before, during, and after passenger loading & unloading as a signal for all other traffic to stop.
- Amber or Yellow lights are often used by utility vehicles such as construction vehicles, tow trucks, snow plows, funeral escorts and hearses, security patrol vehicles or other vehicles which may be stopped or moving slower than the flow of traffic. Amber is usually the most permissively regulated color.
- White is often used as an optional color on lightbars, though it may be restricted to emergency vehicles in some states. It is rarely used as the only color on a lightbar, though some states[Note 1] require flashing white beacons on school buses. Certain railroad-related machines, like fueling tankers or switching engines, may also use a flashing white light. Certain government vehicles, such as rural mail delivery vehicles, use a flashing white beacon in some states.
- Green emergency lighting since 9/11 is now used by Homeland Security Agencies and Government/private security agencies protecting high risk government and Critical Infrastructure. Green Emergency lighting is being used on the vehicles which are protecting nuclear facilities, oil & gas depots, water storage facilities and dams, gas pipelines, Airports, defense facilities, maritime facilities, and all other areas which are at a high risk of terrorist attacks. Green emergency lighting is also used by private security agencies securing certain Government buildings and establishments where terrorist organizations may also target. GREEN and BLUE emergency lighting is now used by some Homeland / Counter Terrorism Agencies whilst responding to Terrorist incidents so as to distinguish the specialist agencies from other emergency departments. In the Commonwealth of Puerto Rico Green AND Blue is used by Homeland & National Security agencies by Municipal Police Forces in addition to Counter Terrorism security agencies. In Washington State, under the provisions of RCW 46.37.185 a firefighter may use a green light on their privately owned vehicle with the approval of the fire chief of the department they are employed by. The green light is used for identification purposes only and does not convey any special rights or status to the vehicle.
- Blue is reserved for law enforcement, firefighters and EMTs. In New Mexico and Texas, tow trucks may have blue lights in combination with amber. In Texas, light construction and utility vehicles commonly use blue in combination with amber, though technically illegal. Alaska, Arizona, Colorado, Minnesota, and Nebraska also use blue lights on snowplows.
- Purple is permitted in some states to denote a funeral vehicle.
Police agencies may use red, blue, or both, depending on the state, along with white and amber as optional colors; although amber is usually restricted to face behind the vehicle. Some police cars have an amber traffic-control stick, or "arrow stick", behind the lightbar to direct traffic left or right around the vehicle; these usually have 6 or 8 rear-facing lights that flash in sequence.
Some privately operated special police are allowed to display the same colors as regular police, generally, if they receive their special police authority at the state level. This can include railroad, university, hospital, and humane society police departments.
Fire and EMS
Fire and emergency medical services generally use red and white lights. Vehicles operated by fire departments, such as fire engines and heavy rescue vehicles, prominently use red, a color with strong cultural associations with the fire service, along with some white. Amber, and blue in some states, are also shown towards the rear, and some communities even have lighting on fire trucks not dissimilar to police (Red and Blue). Many fire chiefs' cars have, in addition to the red lights, a single green beacon to indicate command post status. On the other hand, in Chicago and some nearby communities, fire vehicles show a green light on the right, or starboard, side of the vehicle, reflecting nautical tradition.
Emergency medical vehicles, such as ambulances and paramedic fly-cars, generally use white and red, with an amber light facing the rear. Some states have a specific rule authorizing light colors for EMS vehicles, while on the other hand some EMS vehicles "inherit" their light colors from the fire or police department they are operated by or contracted to, and may show blue lights.
The National Fire Protection Association publishes the NFPA-1901 standards for fire vehicles, which specifies the degree of lighting on various parts of the vehicles, with some flexibility as to color. There is also a GSA procurement specification for ambulances known as KKK-A-1822-F, which many local authorities follow.
Many U.S. states allow volunteer fire and EMS personnel to place emergency warning lights in their personal vehicles for use when responding to emergencies. The laws vary greatly by state. For instance, Virginia state law allows emergency personnel to equip one private vehicle "with no more than two flashing or steady-burning red or red and white combination warning lights".
The degree of lighting is mandated by law and also by local custom in most areas, and can vary from a single rotating light on the dashboard or roof, to a setup much like modern police cruisers. Some states also allow volunteer use of sirens and air horns to request the right of way. Some over use lighting systems to a point of being nonsensical and confusing to drivers. These vehicles and operators are called the slang term "Whackers".
In some states, volunteers are allowed to use the normal red lights, while in other states volunteers must use some other color, usually blue or green. In the latter case, the lights are used as a courtesy to "request" the right of way and generally do not mandate pulling over. Some states, such as Pennsylvania, limit volunteer use of red lights to chiefs and captains of squads.
Separate colors may be used for fire versus EMS volunteers. In Connecticut, Indiana, and New York, volunteer firefighters use blue while volunteer EMTs use green. In New Jersey, volunteer fire and ambulance personnel use blue lights in their personal vehicles while responding to their stations. In NJ red lights are only allowed for emergency vehicles, fire chiefs, chief officers of first aid or rescue squads, or other law enforcement vehicles. New York also certifies some volunteer EMTs to use red lights and sirens provided their vehicles carry certain equipment; this is often used by Hatzolah volunteers in the NYC area. Typically in New York state, volunteer firemen use blue lights in their personal vehicles and volunteer EMS use green lights. This may generate confusion, as green lights are also used to signify an incident command vehicle.
The conflicting color assignments can create issues for volunteers who drive their vehicles out of state. While some authorities may be satisfied with covering the lights with an "Out Of Service" tarp, compliance may be more difficult in other jurisdictions. For example, Arkansas bars civilian possession of blue lights on or in a vehicle unless sealed in the manufacturer's original package.
The confusion generated by the different colors in each state can also cause problems for drivers who travel into others states. One color in their state may mean firefighter or EMT when in another state it may mean police, obviously causing problems.
Yellow lights are often used on vehicle involved in non-emergency work. Most utility companies, towing services, and certain types of construction equipment mount some type of lightbar or lighting system for a higher degree of visibility. In Detroit, Michigan, Angels' Night volunteers will patrol neighborhoods with yellow lights to help deter vandalism during Devil's Night and Halloween. Typically these lights are the single beacon kind, although lightbars have been used for vehicles of this type, especially on wreckers/tow trucks. Also in Michigan, emergency road service vehicles (tow trucks, wreckers, etc.) are allowed to use red warning lights only when stationary.
In states that do not enforce specific rules about green, yellow or white lights, they are often used by entities like private security companies which may be ineligible to use blue or red lights but wish to distinguish themselves from utility vehicles. Security vehicles generally use their lights on private property and are generally not allowed a "courtesy" or "emergency" light on public roads.
Often, while certain colors are customarily used by different services, there are other colors that are optionally used, such as amber and white. Sometimes, this is done to satisfy particular regulations; for example, California requires a steady red light facing forward and a flashing amber light to the rear on every emergency vehicle.
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- e.g. Preco's 7600 series
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