Emergency vehicle lighting refers to any of several visual warning devices, which may be known as light bars or beacons, 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 the driver to stop for interaction with an officer.

These are additional to any standard lighting on the car such as hazard lights and are often used along with a siren (or occasionally sirens) in order to maximize 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 .

LED Lighting

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.

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.

Light Bars

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 relocating sirens to the front bumper of emergency vehicles has resulted in many lightbar models eliminating the siren 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.

Use in Canada

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 and purple is used for a funeral. Police now use both red and blue in all provinces, now including Ontario, where the color blue had been reserved for snowplows until recently.

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 or medical responder's private vehicle. 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 homes 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 the provinces of AB, BC, SK, MB, NB, NS, PEI, NL, ON, and the territories of YK, NWT, and NU.
• Red: fire department; and other "non-police" law enforcement in the provinces of BC, ON, and QC.
• Red and White: EMS; and the British Columbia Sheriff Office.
• Blue: snow plows, municipal and private contractors.
• Amber and Blue: snow plows - Manitoba.
• Amber: construction and utility; funeral homes; airport service vehicles.
• Purple: funeral homes - Ontario, Alberta, Manitoba, and Prince Edward Island.
• Green: emergency service volunteers and 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

Use in the United States

In the United States, colors are generally regulated at the state level, 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.
• Amber or Yellow lights are often used by vehicles such as construction vehicles, tow trucks, snow plows, funeral escorts, 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 Arkansas, Rhode Island, Florida, Illinois, Michigan, Wisconsin, Maryland, West Virginia, South Dakota and Kentucky require flashing white beacons on school buses. Certain railroad-related machines, like fueling tankers or switching engines, may also use a flashing white light.
• Green on a fire chief's car or a mobile command post denotes the command vehicle on scene; this usage derives from the use of green flags in the Incident Command System. Green can also denote a firefighter or EMT's vehicle in some states. In some states, green is used by private security guards.
• Blue is reserved for law enforcement, firefighters and EMTs. In New Mexico, tow trucks have blue lights. In Texas light Construction vehicles use Blue along with Amber. Alaska, Arizona, Colorado, Minnesota, and Nebraska also use blue lights on snowplows.
• Purple is permitted in some states to denote a funeral vehicle.

Police

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. 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.

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