Automotive lighting
Encyclopedia
The lighting system of a motor vehicle consists of light
ing and signalling devices mounted or integrated to the front, sides, rear, and in some cases the top of the motor vehicle
. The purpose of this system is to provide illumination
for the driver to operate the vehicle safely after dark, to increase the conspicuity of the vehicle, and to display information about the vehicle's presence, position, size, direction of travel, and driver's intentions regarding direction and speed of travel.
The colour of light emitted by vehicle lights is largely standardised by longstanding convention, first codified in the 1949 Vienna Convention on Road Traffic
and later specified in the 1968 United Nations
Convention on Road Traffic. Generally, but with some regional exceptions, lamps facing rearward must emit red light, lamps facing sideward and all turn signals must emit amber light, lamps facing frontward must emit white or selective yellow
light, and no other colours are permitted except on emergency vehicles.
s, which may be augmented by auxiliary fog lamps, driving lamps, and/or cornering lamps.
.
"Driving lamp" is a term deriving from the early days of nighttime driving, when it was relatively rare to encounter an opposing vehicle. Only on those occasions when opposing drivers passed each other would the dipped or "passing" beam be used. The full beam was therefore known as the "driving beam", and this terminology is still found in international ECE Regulations, which do not distinguish between a vehicle's primary (mandatory) and auxiliary (optional) upper/driving beam lamps. The "driving beam" term has been supplanted in North American regulations by the functionally descriptive term "auxiliary high-beam lamp". They are most notably fitted on rallying
cars, and are occasionally fitted to production vehicles derived from or imitating such cars. They are common in countries with large stretches of unlit roads, or in regions such as the Nordic countries
where the period of daylight is short during winter. Many countries regulate the installation and use of driving lamps. For example, in Russia each vehicle may have no more than three pairs of lights including the original-equipment items, and in Paraguay, auxiliary driving lamps must be off and covered with opaque material when the vehicle is circulating in urban areas.
, off-roading
, or at very high speeds often have extra lamps to broaden and extend the field of illumination in front of the vehicle. On off-road vehicles in particular, these additional lamps are sometimes mounted along with forward-facing lights on a bar above the roof, which protects them from road hazards and raises the beams allowing for a greater projection of light forward.
Front fog lamps provide a wide, bar-shaped beam of light with a sharp cutoff at the top, and are generally aimed and mounted low. They may be either white or selective yellow
. They are intended for use at low speed to increase the illumination directed towards the road surface and verges in conditions of poor visibility due to rain
, fog
, dust
or snow
. As such, they are often most effectively used in place of dipped-beam headlamps, reducing the glareback from fog or falling snow, although the legality varies by jurisdiction of using front fog lamps without low beam headlamps.
Use of the front fog lamps when visibility is not seriously reduced is often prohibited (for example in the United Kingdom
), as they can cause increased glare to other drivers, particularly in wet pavement conditions, as well as harming the driver's own vision due to excessive foreground illumination.
The respective purposes of front fog lamps and driving lamps are often confused, due in part to the misconception that fog lamps are necessarily selective yellow
, while any auxiliary lamp that makes white
light is a driving lamp. Automakers and aftermarket parts and accessories suppliers frequently refer interchangeably to "fog lamps" and "driving lamps" (or "fog/driving lamps"). In most countries, weather conditions rarely necessitate the use of fog lamps, and there is no legal requirement for them, so their primary purpose is frequently cosmetic. They are often available as optional extras or only on higher trim levels of many cars. Studies have shown that in North America more people inappropriately use their fog lamps in dry weather than use them properly in poor weather.
On some models, white "cornering lamps" provide extra lateral illumination in the direction of an intended turn or lane change. These are actuated in conjunction with the turn signals, though they burn steadily, and they may also be wired to illuminate when the vehicle is shifted into reverse gear, as is done on many Saab
s and Corvettes
. North American technical standards contain provisions for front cornering lamps as well as for rear cornering lamps. Cornering lamps have traditionally been prohibited under international ECE Regulations, though provisions have recently been made to allow them as long as they are only operable when the vehicle is travelling at less than 40 kilometres per hour (about 25 mph).
Conspicuity devices are the lamps and reflectors that make a vehicle conspicuous and visible with respect to its presence, position, direction of travel, change in direction or deceleration. Such lamps may burn steadily, blink, or flash, depending on their intended and regulated function.
. Despite the UK term, these are not the same as the sidemarker lights described below. The front position lamps may emit white or amber light in North America; elsewhere in the world they must emit only white light. Colloquial city light terminology for front position lamps derives from the practice, formerly adhered to in cities like Moscow, London and Paris, of driving at night in built-up areas using these low-intensity
lights rather than headlamps. It is now illegal in many countries to drive a vehicle with parking lamps illuminated, unless the headlamps are also illuminated. The UK briefly required Dim-Dip lights, described below, in an attempt to optimise the level of light used at night in built-up areas.
Since the late 1960s, front position lamps have been required to remain illuminated even when the headlamps are on, to maintain the visual signature of a dual-track vehicle to oncoming drivers in the event of headlamp burnout. Front position lamps worldwide produce between 4 and 125 candela
s.
In Germany, the StVZO (Road Traffic Licensing Regulations) calls for a different function also known as parking lamps: With the vehicle's ignition switched off, the operator may activate a low-intensity light at the front (white or amber) and rear (red) on either the left or the right side of the car. This function is used when parking in narrow unlit streets to provide parked-vehicle conspicuity to approaching drivers. This function, which is optional under ECE and US regulations, is served passively and without power consumption in North America by the mandatory sidemarker retroreflectors.
Some countries permit or require vehicles to be equipped with daytime running lamps (DRL). These may be functionally-dedicated lamps, or the function may be provided by, e.g., the low beam or high beam headlamps, the front turn signals, or the front fog lamps, depending on local regulations. In ECE Regulations, a functionally-dedicated DRL must emit white light with an intensity of at least 400 candelas on axis and no more than 1200 candelas in any direction. Most countries applying ECE Regulations permit low beam headlamps to be used as daytime running lamps. Canada
, Sweden
, Norway
, Slovenia
, Finland
, Iceland
, and Denmark
require hardwired automatic DRL systems of varying specification depending on the specific country. DRLs are permitted in many countries where they are not required, but prohibited in other countries not requiring them.
In North America, daytime running lamps may produce up to 7,000 candelas, and can be implemented as high-beam headlamps running at less-than-rated voltage. This has provoked a large number of complaints about glare
.
Front, side, and rear position lamps are permitted, required or forbidden to illuminate in combination with daytime running lamp
s, depending on the jurisdiction and the DRL implementation. Likewise, according to jurisdictional regulations, DRLs mounted within a certain distance of turn signals are permitted or required to extinguish or dim down to parking lamp intensity individually when the adjacent turn signal is operating.
regulations briefly required vehicles first used on or after 1 April 1987 to be equipped with a dim-dip device
or special running lamps, except such vehicles as comply fully with ECE Regulation 48
regarding installation of lighting equipment. A dim-dip device operates the low beam headlamps (called "dipped beam" in the UK) at between 10% and 20% of normal low-beam intensity. The running lamps permitted as an alternative to dim-dip were required to emit at least 200 candela straight ahead, and no more than 800 candela in any direction. In practice, most vehicles were equipped with the dim-dip option rather than the running lamps.
The dim-dip systems were not intended for daytime use as DRLs
. Rather, they operated if the engine was running and the driver switched on the parking lamps (called "sidelights" in the UK). Dim-dip was intended to provide a nighttime "town beam" with intensity between that of the parking lamps commonly used at the time by British drivers in city traffic after dark, and dipped (low) beams; the former were considered insufficiently intense to provide improved conspicuity in conditions requiring it, while the latter were considered too glaring for safe use in built-up areas. The UK was the only country to require such dim-dip systems, though vehicles so equipped were sold in other Commonwealth
countries with left-hand traffic.
In 1988, the European Commission
successfully prosecuted the UK government in the European Court of Justice
, arguing that the UK requirement for dim-dip was illegal under EC directives prohibiting member states from enacting vehicle lighting requirements not contained in pan-European EC directives. As a result, the UK requirement for dim-dip was quashed. Nevertheless, dim-dip systems remain permitted, and while such systems are not presently as common as they once were, dim-dip functionality was fitted on many new cars well into the 1990s.
In North America, amber front and red rear sidemarker lamps and retro-reflectors are required. The law initially required lights or retroreflectors on vehicles made after 1 January 1968. This was amended to require lights and retroreflectors on vehicles made after 1 January 1970. These side-facing devices make the vehicle's presence, position and direction of travel clearly visible from oblique angles. The lights are wired so as to illuminate whenever the vehicles' parking and taillamps are on, including when the headlamps are being used. Front amber sidemarkers in North America may or may not be wired so as to flash in sync with the turn signals. Sidemarkers are permitted outside North America, but not required. If installed, they are required to be brighter and visible through a larger horizontal angle than US sidemarkers, they may not flash, and they must be amber at the front and rear unless the rear sidemarker is incorporated into the main rear lamp cluster, in which case it may be red or amber. Some Japanese, European, British and US-brand vehicles have sidemarkers in Europe and other countries where they are not required.
Japan
's recent accession to internationalised ECE Regulations has caused automakers to change the rear sidemarker colour from red to amber on their models so equipped in the Japanese market.
Turn signals — formally called "directional indicators" or "directional signals", and informally known as "directionals", "blinkers", "indicators" or "flashers" — are signal light
s mounted near the left and right front and rear corners of a vehicle, and sometimes on the sides, used to indicate to other drivers that the operator intends a lateral change of position (turn or lane change). Electric
turn signal lights were devised as early as 1907. The modern turn signal was patented in 1938 and was later offered by most major automobile manufacturers. Today, turn signals are required on all vehicles that are driven on public roadways in most countries. Alternative systems of hand signal
s were used earlier, and they are still common for bicycle
s. Hand signals are also sometimes used when regular vehicle lights are malfunction
ing.
Some cars from the 1920s to 1950s used retractable semaphores called trafficators
rather than flashing lights. They were commonly mounted high up behind the front doors and swung out horizontally. However, they were fragile and could be easily broken off and also had a tendency to stick in the closed position.
As with all vehicle lighting and signalling devices, turn signal lights must comply with technical standards that stipulate minimum and maximum permissible intensity levels, minimum horizontal and vertical angles of visibility, and minimum illuminated surface area to ensure that they are visible at all relevant angles, do not dazzle those who view them, and are suitably conspicuous in conditions ranging from full darkness to full direct sunlight.
In most countries outside North America, cars must be equipped with side-mounted turn signal repeaters to make the turn indication visible laterally rather than just to the front and rear of the vehicle. These are permitted, but not required in North America. As an alternative in North America, the front amber sidemarker lights may be wired to flash with the turn signals, but this also is not mandatory. In recent years, many automakers have been incorporating side turn signal devices into the sideview mirror housings, rather than mounting them on the vehicle's fenders. One of the first vehicles so equipped was the Mercedes-Benz R170. There is evidence to suggest these mirror-mounted turn signals may be more effective than fender-mounted items.
Turn signals are required to blink on and off, or "flash", at a steady rate of between 60 and 120 blinks per minute (Although some operate slower than this). International regulations require that all turn signals activated at the same time (i.e., all right signals or all left signals) flash in simultaneous phase with one another; North American regulations also require simultaneous operation, but permit sidemarkers wired for side turn signal functionality to flash in opposite-phase. Worldwide regulations stipulate an audiovisual tell-tale
indicator when the turn signals are activated; this usually takes the form of one combined or separate left and right green indicator lights on the vehicle's instrument cluster, and a cyclical "tick-tock" noise generated electromechanically or electronically. It is also required that audio
and/or visual warning be provided to the vehicle operator in the event of a turn signal's failure to light. This warning is usually provided by a much faster- or slower-than-normal flash rate, visible on the dashboard indicator, and audible via the faster or slower tick-tock sound.
Turn signals are in almost every case activated by means of a horizontal lever (or "stalk") protruding from the side of the steering column, though some vehicles have the lever mounted instead to the dashboard. The outboard end of the stalk is pushed clockwise to activate the right turn signals, or anticlockwise for the left turn signals. This operation is intuitive; for any given steering manoeuvre, the stalk is pivoted in the same direction as the steering wheel
must be turned. In virtually all left-hand drive
cars, the signal stalk is on the left side of the column. In right-hand drive cars, the signal stalk may be on either side. If the vehicle's wipers
are controlled by a stalk on the opposite side from the signal stalk, a driver unaccustomed to the vehicle may inadvertently activate the wrong control.
Virtually all vehicles (except many motorcycles and commercial semi-tractors) have a turn indicator self-cancelling feature that returns the lever to the neutral (no signal) position as the steering wheel approaches the straight-ahead position after a turn has been made. Depending on the configuration of the steering and self-cancelling systems, large-radius turns may not involve enough steering wheel movement to trip the turn signal switch back to the neutral position automatically. However, if the self-cancelling system is configured to avoid this, it may tend to cancel the turn signal prematurely in response to normal steering wheel movement before and during common turns. Beginning in the late 1960s, indicating for a lane change was facilitated by the addition of a spring-loaded momentary signal-on position just shy of the left and right detents. The signal operates for however long the driver holds the lever partway towards the left or right turn signal detent. Some recent vehicles have an automatic lane-change indication feature; tapping the lever partway towards the left or right signal position and immediately releasing it causes the applicable turn indicators to flash three to five times.
Many transit bus
es, such as those in New York
, have, since at least the 1950s, had turn signals activated by floor-mounted momentary-contact footswitches on the floor near the driver's left foot (on left-hand drive buses). The foot-activated signals allow bus drivers to keep both hands on the steering wheel while watching the road and scanning for passengers as they approach a bus stop. New York City Transit bus drivers, among others, are trained to step continuously on the right directional switch while servicing a bus stop, to signal other road users they are intentionally dwelling at the stop, allowing following buses to skip that stop. This method of signalling requires no special arrangements for self-cancellation or passing.
Until the early 1960s, most front turn signals worldwide emitted white light and most rear turn signals emitted red. Amber front turn signals were voluntarily adopted by the auto industry in the USA for most vehicles beginning in the 1963 model year, though front turn signals were still legally permitted to emit white light until FMVSS 108
took effect for the 1968 model year, whereupon amber became the only permissible front turn signal colour. Presently, almost all countries outside North America require that all front, side and rear turn signals produce amber
light. In North America the rear signals may be amber or red. American regulators and other proponents of red rear turn signals have historically asserted there is no proven safety benefit to amber signals, though it has been recognised since the 1960s that amber turn signals are more quickly spotted than red ones. International proponents of amber rear signals say they are more easily discernible as turn signals, and U.S. studies in the early 1990s demonstrated improvements in the speed and accuracy of following drivers' reaction to stop lamps when the turn signals were amber rather than red. A 2008 U.S. study by the National Highway Traffic Safety Administration
(NHTSA) suggests vehicles with amber rear signals rather than red ones are up to 28% less likely to be involved in certain kinds of collisions, and a 2009 NHTSA study determined there is a significant overall safety benefit to amber rather than red rear turn signals.
There is some evidence that turn signals with colourless clear lenses and amber bulbs may be less conspicuous in bright sunlight than those with amber lenses and colourless bulbs.
The amber bulbs commonly used in turn signals with colourless lenses are no longer made with cadmium
glass, since cadmium was banned because of its toxicity by various regulations worldwide, including the European RoHS directive. Amber glass made without cadmium is relatively costly, so most amber bulbs are now made with clear glass dipped in an amber coating. Some of these coatings are not as durable as the bulbs themselves; with prolonged heat-cool cycles, the coating may flake off the bulb glass, or its colour may fade. This causes the turn signal to emit white light rather than the required amber light. The international regulation on motor vehicle bulbs requires manufacturers to test bulbs for colour endurance. However, no test protocol or colour durability requirement is specified. Discussion is ongoing within the Groupe des Rapporteurs d'Éclairage, the UNECE working group on vehicular lighting regulation, to develop and implement a colour durability standard. Rather than using an amber bulb, some signal lamps contain an inner amber plastic enclosure between a colourless bulb and the colourless outer lens. With the development of high power amber LED lights, it is possible that filament bulbs for turn signals will be made obsolete within a few years.
Sequential turn signals are a feature on some cars
whereby multiple lights that produce the rear turn signal do not all flash on and off in phase. Rather, the horizontally arrayed lamps are illuminated sequentially: the innermost lamp lights and remains illuminated, the next outermost lamp lights and remains illuminated, followed by the next outermost lamp and so on until the outermost lamp lights briefly, at which point all lamps extinguish together and, after a short pause, the cycle begins again. The visual effect is one of outward motion in the direction of the intended turn or lane change. This implementation has generally been found only on American cars that use combination red rear stop and turn signal lamps.
Sequential turn signals were factory fitted to Ford Thunderbird
s built between 1965 and 1971, inclusive, to Mercury Cougar
s between 1967 and 1973, to Shelby Mustang
s between 1967 and 1970, to 1969 Imperial
s (division of Chrysler
Corp), to the JDM 1971 Nissan Cedric
, and to current Ford Mustang
s. The system is costly and complex relative to standard turn signals, and no other production cars were so equipped.
Two different systems were employed. The earlier, fitted to the 1965 through 1968 Ford
-built cars, was electro-mechanical, featuring an electric motor
driving, through reduction gearing, a set of three slow-turning cam
s. These cams would actuate switches to turn on the lights in sequence so long as the turn signal switch was set. This system was complicated and prone to failure, and the units no longer function in many surviving cars. Later Ford cars and the 1969 Imperial
used a transistorised
control module with no moving parts.
FMVSS 108 has been officially interpreted as requiring all turn signal lights to illuminate simultaneously. However, the 2010 and newer Ford Mustang
s are equipped with sequential turn signals.
Regulations worldwide stipulate minimum intensity ratios between the bright (stop) and dim (tail) modes, so that a vehicle displaying rear position lamps will not be mistakenly interpreted as showing stop lamps, and vice versa.
Many modern designs use LED lighting sources beginning in 1999 with the 2000 Cadillac Deville
.
s. These are called "stop lamps", or, colloquially, "brake lights". They are required to be fitted in multiples of two, symmetrically at the left and right edges of the rear of every vehicle. Outside North America, the range of acceptable intensity for a stop lamp containing one light source (e.g. bulb) is 60 to 185 candelas. In North America, the acceptable range for a single-compartment stop lamp is 80 to 300 candelas.
In North America
since 1986, in Australia
and New Zealand
since 1990, and in Europe
since 1998, a central brake lamp, mounted higher than the vehicle's left and right brake lamps and called a "Centre High Mount Stop Lamp (CHMSL)", is also required. The CHMSL is also sometimes referred to as the "centre brake lamp", the "third brake light", the "eye-level brake lamp", the "safety brake lamp", or the "high-level brake lamp". The CHMSL may produce light by means of a single central filament bulb, a row or cluster of filament bulbs or LED
s, or a strip of Neon tube
.
The CHMSL is intended to provide a deceleration warning to following drivers whose view of the vehicle's left and right stop lamps is blocked by interceding vehicles. It also helps to disambiguate brake vs. turn signal messages in North America, where red rear turn signals identical in appearance to stop lamps are permitted, and also can provide a redundant stop light signal in the event of a stop lamp malfunction.
The CHMSL is generally required to illuminate steadily and not permitted to flash, though U.S. regulators granted Mercedes-Benz
a temporary, limited exemption to the steady-light requirement so as to evaluate whether a flashing CHMSL provides an emergency stop signal that effectively reduces the likelihood of a crash.
On passenger cars, the CHMSL may be placed above the back glass, affixed to the vehicle's interior just inside the back glass, or it may be integrated into the vehicle's deck lid or into a spoiler
. Other specialised fitments are sometimes seen; the Jeep Wrangler
and Land Rover Freelander
have the CHMSL on a stalk fixed to the spare wheel carrier. Trucks, vans and commercial vehicles sometimes have the CHMSL mounted to the trailing edge of the vehicle's roof. The CHMSL is required by regulations worldwide to be centred laterally on the vehicle, though ECE R48 permits lateral offset of up to 15 cm if the vehicle's lateral centre is not coincident with a fixed body panel, but instead separates movable components such as doors. The Renault Master
van, for example, uses a laterally offset CHMSL for this reason. The height of the CHMSL is also regulated, in absolute terms and with respect to the mounting height of the vehicle's conventional left and right stop lamps. Depending on the left and right lamps' height, the lower edge of the CHMSL may be just above the left and right lamps' upper edge.
The 1952 Volkswagen Bus
was equipped with a center-mounted brake light in addition to the two conventional brake lights. The 1968 - 1971 Ford Thunderbird
could be ordered with optional supplemental high-mounted stop and turn signal lights integrated into the left and right interior trim surrounding the backglass. The Oldsmobile Toronado
from 1971 to 1978, and the Buick Riviera
from 1974 to 1976 had similar dual high-mounted supplemental stop/turn lights as standard equipment; these were located on the outside of the vehicle below the bottom of the backglass. This type of configuration was not widely adopted at the time. Auto and lamp manufacturers in Germany
experimented with dual high-mount supplemental stop lamps in the early 1980s, but this effort, too, failed to gain wide popular or regulatory support.
Early studies involving taxicab
s and other fleet vehicles found that a third stop lamp reduced rear-end collisions by about 50%. The lamp's novelty probably played a role, since today the lamp is credited with reducing collisions by about 5%.
In 1986, the United States
National Highway Traffic Safety Administration
and Transport Canada
mandated that all new passenger cars have a CHMSL installed. A CHMSL was required on all new light trucks and vans starting in 1994. CHMSLs are so inexpensive to incorporate into a vehicle that even if the lamps prevent only a few percent of rear end collisions they remain a cost-effective safety feature.
Toyota, Mercedes-Benz
, Volvo
, and BMW
have released vehicles equipped to convey a special light signal when the vehicle is braked rapidly and severely. This is officially referred to as "Emergency Stop Signal", and ECE Regulation 48 calls for the lamps providing the ESS to flash at 4 Hz
when a passenger car decelerates at greater than 6 m/s2 or a truck or bus decelerates at greater than 4 m/s2. Mercedes vehicles flash the stop lamps for the ESS, while vehicles from the Volkswagen
Group of manufacturers (VW, Audi
, SEAT
& Skoda
) flash the hazard flashers.
Other methods of severe-braking indication have also been implemented; some Volvo models make the stop lamps brighter, and some BMWs have "Adaptive Brake Lights" that effectively increase the size of the stop lights under severe braking by illuminating the tail lamps at brighter-than-normal intensity. As long as the brighter-than-normal stop lamps are within the regulated maximum intensity for stop lamps in general, this kind of implementation does not require specific regulatory approval since the stop lamps are under all conditions operating in accord with the general regulations on stop lamps.
The idea behind such emergency-braking indicator systems is to catch following drivers' attention with special urgency. However, there remains considerable debate over whether the system offers a measurable increase in safety performance. To date, studies of vehicles in service have not shown any significant such improvement. The systems used by BMW, Volvo, and Mercedes differ not only in operational mode (growing vs. intensifying vs. flashing, respectively), but also in such parameters as deceleration threshold of activation. Data are being collected and analyzed in an effort to determine how such a system might be implemented to maximise a safety benefit, if such a benefit can be realised with visual emergency braking displays. An experimental study at the University of Toronto has tested stop lights which gradually and continuously grow in illuminated area with increasing vehicle deceleration rate (i.e., increasing brake application pressure).
One potentially problematic factor in the implementation of flashing stop lamps in North America is that North American regulations permit flashing stop lamps to be used in lieu of separate rear turn signal and hazard warning lamps.
In Europe and other countries adhering to ECE Regulation 48, vehicles must be equipped with one or two bright red "rear fog
lamps" (or "fog taillamps"), which serve as high-intensity rear position lamps to be energised by the driver in conditions of poor visibility to enhance vehicle conspicuity from the rear. The allowable range of intensity for a rear fog lamp is 150 to 300 candelas, which is within the range of a U.S. stop lamp. For this reason, some European vehicles imported to the United States have their rear fog lamps wired as stop lamps, since their European-specification stop lamps may not be sufficiently intense to comply with U.S. regulations, and in North America rear fog lamps are not required equipment. However, they are permitted, and are found almost exclusively on European-brand vehicles in North America — Audi, Jaguar, Mercedes, MINI, Land Rover, Porsche, Saab and Volvo provide functional rear fog lights on their North American models. The final generation Oldsmobile Aurora
also had dual rear fog lights installed in the rear bumper as standard equipment.
Most jurisdictions permit rear fog lamps to be installed either singly or in pairs. If a single rear fog is fitted, most jurisdictions require it to be located at or to the driver's side of the vehicle's centreline — whichever side is the prevailing driver's side in the country in which the vehicle is registered. This is to maximise the sight line of following drivers to the rear fog lamp. In many cases, a single reversing lamp is mounted on the passenger side of the vehicle, positionally symmetrical with the rear fog. If two rear fog lamps are fitted, they must be symmetrical with respect to the vehicle's centreline. Proponents of twin rear fog lamps say two lamps provide vehicle distance information not available from a single lamp. Proponents of the single rear fog lamp say dual rear fog lamps closely mimic the appearance of illuminated stop lamps (which are mandatorily installed in pairs), reducing the conspicuity of the stop lamps' message when the rear fogs are activated. To provide some safeguard against rear fog lamps being confused with stop lamps, ECE R48 requires a separation of at least 10 cm between the closest illuminated edges of any stop lamp and any rear fog lamp.
To provide illumination to the rear when backing up, and to warn adjacent vehicle operators and pedestrians of a vehicle's rearward motion, each vehicle must be equipped with at least one rear-mounted, rear-facing reversing lamp (or "backup light"). These are currently required to produce white light by U.S. and international ECE regulations. However, some countries have at various times permitted amber reversing lamps. In Australia and New Zealand, for example, vehicle manufacturers were faced with the task of localising American cars originally equipped with combination red stop/turn signal lamps and white reversing lamps. Those countries' regulations permitted the amber rear turn signals to burn steadily as reversing lamps, so automakers and importers were able to combine the (mandatorily amber) rear turn signal and (optionally amber) reversing lamp function, and so comply with the regulations without the need for additional lighting devices. Both countries presently require white reversing lamps, so the combination amber turn/reverse lamp is no longer permitted on new vehicles. The U.S. state of Washington presently permits reversing lamps to emit white or amber light.
and buses
are in many cases required to carry additional lighting devices beyond those required on passenger vehicles. The specific requirements vary according to the regulations in force where the vehicle is registered and/or operated.
in Australia.
must be provided to the driver. In vehicles with a separate left and right green turn signal tell-tale on the dashboard, both left and right indicators may flash to provide visual indication of the hazard flashers' operation. In vehicles with a single green turn signal tell-tale on the dashboard, a separate red tell-tale must be provided for hazard flasher indication. Because the hazard flasher function operates the vehicle's left and right turn signals, a left or a right turn signal function cannot be provided while the hazard flashers are operating.
"Retroreflector
s" (also "reflex reflectors") produce no light of their own, but rather reflect incident light back towards its source, e.g., another driver's headlight. They are regulated as automotive lighting devices, and specified so as to account for the separation between a vehicle's headlamps and its driver's eyes. Thus, vehicles are conspicuous even when their electrically powered lighting system is off or disabled. Regulations worldwide require each vehicle to be equipped with rear-facing red retroreflectors. Since 1968 North American regulations also require side-facing retroreflectors, amber in front and red in the rear. Sweden, South Africa and other countries have at various times required white front-facing retroreflectors.
and Idaho
, permit vehicles to be equipped with auxiliary rear signal systems displaying green light when the accelerator is depressed, yellow light when the vehicle is coasting, and red light when the brake is depressed.
Such systems have in the past been sold as aftermarket
accessories, but are today seldom seen in traffic.
, among other bodies, has commissioned studies of these and many other vehicle signal systems and configurations, in an effort to determine the most promising avenues and best practices for enhanced crash avoidance via optimised vehicle conspicuity and signal lighting systems.
LED light sources are beginning to appear increasingly as interior convenience lights in various locations as the technology becomes more widely used, especially with finely focused lighting on console control surfaces and in cabin storage areas.
There may be additional map
lights that are aimed at specific passenger positions, that allow for reading without particular glare distraction to the driver. Some vehicles have "approach lighting" (puddle lights) integrated into the exterior mirrors or lower edges of the doors, as well as activating interior lighting, that is activated via key fob. Many cars have lights in the trunk
(or boot), the engine compartment, and the glovebox
and other storage compartments.
Most instruments and controls on a dashboard
in modern vehicles are illuminated in some fashion when the headlamps are turned on, and the intensity of light can be adjusted by the driver for comfort. Saabs feature an aerospace technologies-derived "night panel" function which shuts off all interior illumination save for the speedometer (unless attention is called to a critical situation on another gauge) to improve the driver's night vision.
Emergency vehicle
s such as fire engines, ambulance
s, police car
s, snow-removal vehicles
and tow truck
s are usually equipped with intense warning lights of particular colours. These may be motorised rotating beacons, xenon strobes, or arrays of LED
s. The prescribed colours differ by jurisdiction; in most countries, blue and/or red special warning lamps are used on police, fire, and medical-emergency vehicles. In North America and some other jurisdictions, amber lights are for tow trucks, private security personnel, construction vehicles, and other nonofficial special-service vehicles, while volunteer firefighters use red, blue, or green, depending on jurisdiction. In the UK, doctors may use green warning lamps. Special warning lights, usually amber, are also sometimes mounted on slow vehicles such as mobile crane
s, excavator
s, tractor
s, and even mobility scooter
s in certain conditions.
s are distinguished by special lights according to local regulations.
They may have an illuminated "Taxi" sign, a light to signal that they are ready to take passengers or off duty, and/or an emergency panic light the driver can activate in the event of a robbery to alert passersby to call the police.
Traditionally, an tungsten
incandescent light bulb
has been the light source used in all of the various automotive signalling and marking lamps. Typically, bulbs of 21 to 27 watt
s, producing 280 to 570 lumens
(22 to 45 mean spherical candlepower
) are used for stop, turn, reversing and rear fog lamps, while bulbs of 4 to 10 W, producing 40 to 130 lm
(3 to 10 mscp) are used for tail lamps, parking lamps, sidemarker lamps and side turn signal repeaters. These bulbs typically have either a metal bayonet base
or a plastic or glass wedge base
for the physical and electrical interface with the lamp socket.
Tungsten-halogen light bulbs are a very common light source for headlamp
s and other forward illumination functions. Some recent-model vehicles use small halogen bulbs for exterior signalling and marking functions, as well. The first halogen lamp approved for automotive use was the H1
, which was introduced in Europe in 1962.
Xenon is currently the lamp used in single-source lighting systems being developed for automotive use. In these systems, a single light source sends light via optical fibers to wherever it is needed in the automobile. This development, known as distributive lighting, is already appearing in the interior lighting features, for example the Ford Mustang's interior lighting. In an expanded system, the light could be channeled to the side mirrors for example, which would act as forward driving lights that could be made to swivel in position with the car as it turns. The headlight pattern would not be limited to individual overlapping beams, but could be channeled by electronic controls of the fiber optics to provide optimum visibility over an extended range of driving conditions including fog, dust or snow. Individual lamps would not be needed, just a mounting point for the optical fibers running back to the single light source and computer controlled for colour, intensity and continuity.
tubes were introduced into widespread production for the CHMSL on the 1995 Ford Explorer
, and notable later uses included the 1998 Lincoln Mark VIII
, with a neon tube spanning the width of the trunk decklid, and the BMW Z8
, which made extensive use of neon. Numerous concept cars have included neon lamp features, from such manufacturers as Volvo
. Hella
offered an aftermarket neon CHMSL in the late 1990s.
The linear packaging of the neon light source lends itself to the linear packaging favored for many CHMSL installations, and neon lights offer the same nearly instant rise time benefit as LEDs. However, neon tubes require an expensive and relatively power-hungry ballast (power supply unit), and as a result, neon lights have not found significant long-term popularity as sources of light for automotive signaling.
s are being used with increasing frequency in automotive lamps. They offer very long service life
, extreme vibration resistance, and can permit considerably shallower packaging compared to most bulb-type assemblies. LEDs also offer a significant safety performance benefit when employed in stop lights, for when power is applied they rise to full intensity approximately 200 milliseconds (0.2 seconds) faster than incandescent bulbs. This fast rise time
not only improves the attentional conspicuity of the stop lamp, but also provides following drivers with increased time in which to react to the appearance of the stop lamps.
LEDs were first applied to automotive lighting in Centre High Mount Stop Lamps (CHMSL), beginning in the late 1980s. Adoption of LEDs for other signal functions on passenger cars has been slow, but is beginning to increase with demand for the technology and related styling updates. The 2007 Audi R8 sports car uses two strips of optically-focused high-intensity LEDs for its Daytime Running Lamps
. Optional on the R8 in ECE markets is the world's first LED headlamp made by AL-Automotive Lighting. The low and high beams along with the position (parking) lamp and front turn signal are all realised with LEDs. The Lexus LS 600h features LED low beam, position and sidemarker lamps in North America, and the 2009 Cadillac Escalade
Platinum uses LEDs for the low and high beams, as well as for the position and sidemarker lamps.
The commercial vehicle industry has rapidly adopted LEDs for virtually all signaling and marking functions on trucks and buses, because in addition to the fast rise time and concomitant safety benefit, LEDs' extremely long service life reduces vehicle downtime. Almost all commercial vehicles use exterior lighting devices of standardised format and fitment, which has cost-reduced and sped the changeover.
LED lamps have been proven to be a feasible alternative to traditional light sources for flashing beacon lights on vehicles such as maintenance trucks. Previously, traditional light sources required the engine to continue running to ensure that the battery would not get worn out if the lights were to be used for more than a few hours. The energy-efficient nature of the LED source allows the engine to remain turned off but the light to continue to flash.
explicitly permit vehicle signal lamps with intensity automatically increased during bright daylight hours when sunlight reduces the effectiveness of the stop lamps, and automatically decreased during hours of darkness when glare could be a concern. Both US and ECE regulations contain provisions for determining the minimum and maximum acceptable intensity for lamps that contain more than a single light source.
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
ing and signalling devices mounted or integrated to the front, sides, rear, and in some cases the top of the motor vehicle
Motor vehicle
A motor vehicle or road vehicle is a self-propelled wheeled vehicle that does not operate on rails, such as trains or trolleys. The vehicle propulsion is provided by an engine or motor, usually by an internal combustion engine, or an electric motor, or some combination of the two, such as hybrid...
. The purpose of this system is to provide illumination
Lighting
Lighting or illumination is the deliberate application of light to achieve some practical or aesthetic effect. Lighting includes the use of both artificial light sources such as lamps and light fixtures, as well as natural illumination by capturing daylight...
for the driver to operate the vehicle safely after dark, to increase the conspicuity of the vehicle, and to display information about the vehicle's presence, position, size, direction of travel, and driver's intentions regarding direction and speed of travel.
Colour of light emitted
Vienna Convention on Road Traffic
The Vienna Convention on Road Traffic is an international treaty designed to facilitate international road traffic and to increase road safety by standardising the uniform traffic rules among the contracting parties...
and later specified in the 1968 United Nations
United Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...
Convention on Road Traffic. Generally, but with some regional exceptions, lamps facing rearward must emit red light, lamps facing sideward and all turn signals must emit amber light, lamps facing frontward must emit white or selective yellow
Selective yellow
Selective yellow is a colour for automotive lamps. Under ECE regulations, headlamps were formerly permitted to be either white or selective yellow — in France, selective yellow was mandatory until 1993....
light, and no other colours are permitted except on emergency vehicles.
Forward illumination
Forward illumination is provided by high- ("main", "full", "driving") and low- ("dip", "dipped", "passing") beam headlampHeadlamp
A headlamp is a lamp, usually attached to the front of a vehicle such as a car or a motorcycle, with the purpose of illuminating the road ahead during periods of low visibility, such as darkness or precipitation. Headlamp performance has steadily improved throughout the automobile age, spurred by...
s, which may be augmented by auxiliary fog lamps, driving lamps, and/or cornering lamps.
Dipped beam (low beam, passing beam, meeting beam)
Dipped-beam (also called low, passing, or meeting beam) headlamps provide a light distribution to give adequate forward and lateral illumination without blinding other road users with excessive glare. This beam is specified for use whenever other vehicles are present ahead. The international ECE Regulations for headlamps specify a beam with a sharp, asymmetric cutoff preventing significant amounts of light from being cast into the eyes of drivers of preceding or oncoming cars. Control of glare is less strict in the North American Society of Automotive Engineers (SAE) beam standard contained in FMVSS / CMVSS 108Federal Motor Vehicle Safety Standard 108
Federal Motor Vehicle Safety Standard 108 regulates all automotive lighting, signalling and reflective devices in the United States. Like all other Federal Motor Vehicle Safety Standards, FMVSS 108 is administered by the United States Department of Transportation's National Highway Traffic Safety...
.
Main beam (high beam, driving beam, full beam)
Main-beam (also called high, driving, or full beam) headlamps provide an intense, centre-weighted distribution of light with no particular control of glare. Therefore, they are only suitable for use when alone on the road, as the glare they produce will dazzle other drivers. International ECE Regulations permit higher-intensity high-beam headlamps than are allowed under North American regulationsFederal Motor Vehicle Safety Standard 108
Federal Motor Vehicle Safety Standard 108 regulates all automotive lighting, signalling and reflective devices in the United States. Like all other Federal Motor Vehicle Safety Standards, FMVSS 108 is administered by the United States Department of Transportation's National Highway Traffic Safety...
Driving lamps
Rallying
Rallying, also known as rally racing, is a form of auto racing that takes place on public or private roads with modified production or specially built road-legal cars...
cars, and are occasionally fitted to production vehicles derived from or imitating such cars. They are common in countries with large stretches of unlit roads, or in regions such as the Nordic countries
Nordic countries
The Nordic countries make up a region in Northern Europe and the North Atlantic which consists of Denmark, Finland, Iceland, Norway and Sweden and their associated territories, the Faroe Islands, Greenland and Åland...
where the period of daylight is short during winter. Many countries regulate the installation and use of driving lamps. For example, in Russia each vehicle may have no more than three pairs of lights including the original-equipment items, and in Paraguay, auxiliary driving lamps must be off and covered with opaque material when the vehicle is circulating in urban areas.
Rallye and off-road lamps
Vehicles used in rallyingRallying
Rallying, also known as rally racing, is a form of auto racing that takes place on public or private roads with modified production or specially built road-legal cars...
, off-roading
Off-roading
Off-roading is a term for driving a vehicle on unsurfaced roads or tracks, made of materials such as sand, gravel, riverbeds, mud, snow, rocks, and other natural terrain.-Off-road vehicle:...
, or at very high speeds often have extra lamps to broaden and extend the field of illumination in front of the vehicle. On off-road vehicles in particular, these additional lamps are sometimes mounted along with forward-facing lights on a bar above the roof, which protects them from road hazards and raises the beams allowing for a greater projection of light forward.
Front fog lamps
Selective yellow
Selective yellow is a colour for automotive lamps. Under ECE regulations, headlamps were formerly permitted to be either white or selective yellow — in France, selective yellow was mandatory until 1993....
. They are intended for use at low speed to increase the illumination directed towards the road surface and verges in conditions of poor visibility due to rain
Rain
Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...
, fog
Fog
Fog is a collection of water droplets or ice crystals suspended in the air at or near the Earth's surface. While fog is a type of stratus cloud, the term "fog" is typically distinguished from the more generic term "cloud" in that fog is low-lying, and the moisture in the fog is often generated...
, dust
Dust
Dust consists of particles in the atmosphere that arise from various sources such as soil dust lifted up by wind , volcanic eruptions, and pollution...
or snow
Snow
Snow is a form of precipitation within the Earth's atmosphere in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. Since snow is composed of small ice particles, it is a granular material. It has an open and therefore soft structure, unless packed by...
. As such, they are often most effectively used in place of dipped-beam headlamps, reducing the glareback from fog or falling snow, although the legality varies by jurisdiction of using front fog lamps without low beam headlamps.
Use of the front fog lamps when visibility is not seriously reduced is often prohibited (for example in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
), as they can cause increased glare to other drivers, particularly in wet pavement conditions, as well as harming the driver's own vision due to excessive foreground illumination.
The respective purposes of front fog lamps and driving lamps are often confused, due in part to the misconception that fog lamps are necessarily selective yellow
Selective yellow
Selective yellow is a colour for automotive lamps. Under ECE regulations, headlamps were formerly permitted to be either white or selective yellow — in France, selective yellow was mandatory until 1993....
, while any auxiliary lamp that makes white
White
White is a color, the perception of which is evoked by light that stimulates all three types of color sensitive cone cells in the human eye in nearly equal amounts and with high brightness compared to the surroundings. A white visual stimulation will be void of hue and grayness.White light can be...
light is a driving lamp. Automakers and aftermarket parts and accessories suppliers frequently refer interchangeably to "fog lamps" and "driving lamps" (or "fog/driving lamps"). In most countries, weather conditions rarely necessitate the use of fog lamps, and there is no legal requirement for them, so their primary purpose is frequently cosmetic. They are often available as optional extras or only on higher trim levels of many cars. Studies have shown that in North America more people inappropriately use their fog lamps in dry weather than use them properly in poor weather.
Cornering lamps
Saab Automobile
Saab Automobile AB, better known as Saab , is a Swedish car manufacturer owned by Dutch automobile manufacturer Swedish Automobile NV, formerly Spyker Cars NV. It is the exclusive automobile Royal Warrant holder as appointed by the King of Sweden...
s and Corvettes
Chevrolet Corvette
The Chevrolet Corvette is a sports car by the Chevrolet division of General Motors that has been produced in six generations. The first model, a convertible, was designed by Harley Earl and introduced at the GM Motorama in 1953 as a concept show car. Myron Scott is credited for naming the car after...
. North American technical standards contain provisions for front cornering lamps as well as for rear cornering lamps. Cornering lamps have traditionally been prohibited under international ECE Regulations, though provisions have recently been made to allow them as long as they are only operable when the vehicle is travelling at less than 40 kilometres per hour (about 25 mph).
Spot lights
Police cars, emergency vehicles, and those competing in road rallies are sometimes equipped with an auxiliary lamp, sometimes called an alley light, in a swivel-mounted housing attached to one or both a-pillars, directable by a handle protruding through the pillar into the vehicle. Until the mid-1940s, these spot lamps could be found as standard equipment on expensive cars. Until the mid-1960s, they were commonly offered by automakers as model-specific accessory items. Spot lamps are used to illuminate signs, house numbers, and people. Spot lights can also be had in versions designed to mount through the vehicle's roof. In some countries, for example in Russia, spot lights are allowed only on emergency vehicles or for off-road driving.Conspicuity, signal and identification lights
Front position lamps (parking lamps, standing lamps)
Nighttime standing-vehicle conspicuity to the front is provided by "front position lamps", known as "parking lamps" or "parking lights" in North America, and "front sidelights" in British EnglishBritish English
British English, or English , is the broad term used to distinguish the forms of the English language used in the United Kingdom from forms used elsewhere...
. Despite the UK term, these are not the same as the sidemarker lights described below. The front position lamps may emit white or amber light in North America; elsewhere in the world they must emit only white light. Colloquial city light terminology for front position lamps derives from the practice, formerly adhered to in cities like Moscow, London and Paris, of driving at night in built-up areas using these low-intensity
Luminous intensity
In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye...
lights rather than headlamps. It is now illegal in many countries to drive a vehicle with parking lamps illuminated, unless the headlamps are also illuminated. The UK briefly required Dim-Dip lights, described below, in an attempt to optimise the level of light used at night in built-up areas.
Candela
The candela is the SI base unit of luminous intensity; that is, power emitted by a light source in a particular direction, weighted by the luminosity function . A common candle emits light with a luminous intensity of roughly one candela...
s.
In Germany, the StVZO (Road Traffic Licensing Regulations) calls for a different function also known as parking lamps: With the vehicle's ignition switched off, the operator may activate a low-intensity light at the front (white or amber) and rear (red) on either the left or the right side of the car. This function is used when parking in narrow unlit streets to provide parked-vehicle conspicuity to approaching drivers. This function, which is optional under ECE and US regulations, is served passively and without power consumption in North America by the mandatory sidemarker retroreflectors.
Daytime running lamps
Some countries permit or require vehicles to be equipped with daytime running lamps (DRL). These may be functionally-dedicated lamps, or the function may be provided by, e.g., the low beam or high beam headlamps, the front turn signals, or the front fog lamps, depending on local regulations. In ECE Regulations, a functionally-dedicated DRL must emit white light with an intensity of at least 400 candelas on axis and no more than 1200 candelas in any direction. Most countries applying ECE Regulations permit low beam headlamps to be used as daytime running lamps. Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
, Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
, Slovenia
Slovenia
Slovenia , officially the Republic of Slovenia , is a country in Central and Southeastern Europe touching the Alps and bordering the Mediterranean. Slovenia borders Italy to the west, Croatia to the south and east, Hungary to the northeast, and Austria to the north, and also has a small portion of...
, Finland
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
, Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
, and Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
require hardwired automatic DRL systems of varying specification depending on the specific country. DRLs are permitted in many countries where they are not required, but prohibited in other countries not requiring them.
In North America, daytime running lamps may produce up to 7,000 candelas, and can be implemented as high-beam headlamps running at less-than-rated voltage. This has provoked a large number of complaints about glare
Glare (vision)
Glare is difficulty seeing in the presence of bright light such as direct or reflected sunlight or artificial light such as car headlamps at night. Because of this, some cars include mirrors with automatic anti-glare functions....
.
Front, side, and rear position lamps are permitted, required or forbidden to illuminate in combination with daytime running lamp
Daytime running lamp
A daytime running lamp is an automotive lighting device on the front of a roadgoing motor vehicle, installed in pairs, automatically switched on when the vehicle is moving forward, emitting white, yellow, or amber light to increase the conspicuity of the vehicle during daylight...
s, depending on the jurisdiction and the DRL implementation. Likewise, according to jurisdictional regulations, DRLs mounted within a certain distance of turn signals are permitted or required to extinguish or dim down to parking lamp intensity individually when the adjacent turn signal is operating.
Dim-dip lamps
U.K.United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
regulations briefly required vehicles first used on or after 1 April 1987 to be equipped with a dim-dip device
or special running lamps, except such vehicles as comply fully with ECE Regulation 48
World Forum for Harmonization of Vehicle Regulations
The World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe...
regarding installation of lighting equipment. A dim-dip device operates the low beam headlamps (called "dipped beam" in the UK) at between 10% and 20% of normal low-beam intensity. The running lamps permitted as an alternative to dim-dip were required to emit at least 200 candela straight ahead, and no more than 800 candela in any direction. In practice, most vehicles were equipped with the dim-dip option rather than the running lamps.
The dim-dip systems were not intended for daytime use as DRLs
Daytime running lamp
A daytime running lamp is an automotive lighting device on the front of a roadgoing motor vehicle, installed in pairs, automatically switched on when the vehicle is moving forward, emitting white, yellow, or amber light to increase the conspicuity of the vehicle during daylight...
. Rather, they operated if the engine was running and the driver switched on the parking lamps (called "sidelights" in the UK). Dim-dip was intended to provide a nighttime "town beam" with intensity between that of the parking lamps commonly used at the time by British drivers in city traffic after dark, and dipped (low) beams; the former were considered insufficiently intense to provide improved conspicuity in conditions requiring it, while the latter were considered too glaring for safe use in built-up areas. The UK was the only country to require such dim-dip systems, though vehicles so equipped were sold in other Commonwealth
Commonwealth of Nations
The Commonwealth of Nations, normally referred to as the Commonwealth and formerly known as the British Commonwealth, is an intergovernmental organisation of fifty-four independent member states...
countries with left-hand traffic.
In 1988, the European Commission
European Commission
The European Commission is the executive body of the European Union. The body is responsible for proposing legislation, implementing decisions, upholding the Union's treaties and the general day-to-day running of the Union....
successfully prosecuted the UK government in the European Court of Justice
European Court of Justice
The Court can sit in plenary session, as a Grand Chamber of 13 judges, or in chambers of three or five judges. Plenary sitting are now very rare, and the court mostly sits in chambers of three or five judges...
, arguing that the UK requirement for dim-dip was illegal under EC directives prohibiting member states from enacting vehicle lighting requirements not contained in pan-European EC directives. As a result, the UK requirement for dim-dip was quashed. Nevertheless, dim-dip systems remain permitted, and while such systems are not presently as common as they once were, dim-dip functionality was fitted on many new cars well into the 1990s.
Sidemarker lights and reflectors
Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
's recent accession to internationalised ECE Regulations has caused automakers to change the rear sidemarker colour from red to amber on their models so equipped in the Japanese market.
Turn signals
Lamp (electrical component)
A lamp is a replaceable component such as an incandescent light bulb, which is designed to produce light from electricity. These components usually have a base of ceramic, metal, glass or plastic, which makes an electrical connection in the socket of a light fixture. This connection may be made...
s mounted near the left and right front and rear corners of a vehicle, and sometimes on the sides, used to indicate to other drivers that the operator intends a lateral change of position (turn or lane change). Electric
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
turn signal lights were devised as early as 1907. The modern turn signal was patented in 1938 and was later offered by most major automobile manufacturers. Today, turn signals are required on all vehicles that are driven on public roadways in most countries. Alternative systems of hand signal
Cycling hand signals
Hand signals are given by cyclists and some motorists to indicate their intentions to other traffic. Under the terms of the Vienna Convention on Traffic, bicycles are considered to be vehicles and cyclists are considered to be drivers...
s were used earlier, and they are still common for bicycle
Bicycle
A bicycle, also known as a bike, pushbike or cycle, is a human-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A person who rides a bicycle is called a cyclist, or bicyclist....
s. Hand signals are also sometimes used when regular vehicle lights are malfunction
Malfunction
A malfunction is when something functions wrongly or does not function at all.Some types of malfunctions are:*Malfunction , malfunction of a parachute*Sexual malfunction, also called "sexual dysfunction"**See also dyspareunia...
ing.
Trafficators
Trafficators are semaphore signals which, when operated, protrude from the bodywork of a motor vehicle to indicate its intention to turn in the direction indicated by the pointing signal. Trafficators are often located at the door pillar.-History:...
rather than flashing lights. They were commonly mounted high up behind the front doors and swung out horizontally. However, they were fragile and could be easily broken off and also had a tendency to stick in the closed position.
As with all vehicle lighting and signalling devices, turn signal lights must comply with technical standards that stipulate minimum and maximum permissible intensity levels, minimum horizontal and vertical angles of visibility, and minimum illuminated surface area to ensure that they are visible at all relevant angles, do not dazzle those who view them, and are suitably conspicuous in conditions ranging from full darkness to full direct sunlight.
Side turn signals
In most countries outside North America, cars must be equipped with side-mounted turn signal repeaters to make the turn indication visible laterally rather than just to the front and rear of the vehicle. These are permitted, but not required in North America. As an alternative in North America, the front amber sidemarker lights may be wired to flash with the turn signals, but this also is not mandatory. In recent years, many automakers have been incorporating side turn signal devices into the sideview mirror housings, rather than mounting them on the vehicle's fenders. One of the first vehicles so equipped was the Mercedes-Benz R170. There is evidence to suggest these mirror-mounted turn signals may be more effective than fender-mounted items.
Electrical connection and switching
Tell-tale (automotive)
A tell-tale is an indicator of the status or malfunction of a system within a motor vehicle. Tell-tales consist of a light bulb or an LED which lights up a symbol or text legend...
indicator when the turn signals are activated; this usually takes the form of one combined or separate left and right green indicator lights on the vehicle's instrument cluster, and a cyclical "tick-tock" noise generated electromechanically or electronically. It is also required that audio
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
and/or visual warning be provided to the vehicle operator in the event of a turn signal's failure to light. This warning is usually provided by a much faster- or slower-than-normal flash rate, visible on the dashboard indicator, and audible via the faster or slower tick-tock sound.
Turn signals are in almost every case activated by means of a horizontal lever (or "stalk") protruding from the side of the steering column, though some vehicles have the lever mounted instead to the dashboard. The outboard end of the stalk is pushed clockwise to activate the right turn signals, or anticlockwise for the left turn signals. This operation is intuitive; for any given steering manoeuvre, the stalk is pivoted in the same direction as the steering wheel
Steering wheel
A steering wheel is a type of steering control in vehicles and vessels ....
must be turned. In virtually all left-hand drive
Driving on the left or right
The terms right-hand traffic and left-hand traffic refer to regulations requiring all bidirectional traffic to keep either to the right or the left side of the road, respectively. This is so fundamental to traffic flow that it is sometimes referred to as the rule of the road. This basic rule eases...
cars, the signal stalk is on the left side of the column. In right-hand drive cars, the signal stalk may be on either side. If the vehicle's wipers
Windscreen wiper
A windscreen wiper or windshield wiper is a device used to remove rain and debris from a windscreen or windshield. Almost all motor vehicles, including trains, aircraft and watercraft, are equipped with such wipers, which are usually a legal requirement.A wiper generally consists of an arm,...
are controlled by a stalk on the opposite side from the signal stalk, a driver unaccustomed to the vehicle may inadvertently activate the wrong control.
Virtually all vehicles (except many motorcycles and commercial semi-tractors) have a turn indicator self-cancelling feature that returns the lever to the neutral (no signal) position as the steering wheel approaches the straight-ahead position after a turn has been made. Depending on the configuration of the steering and self-cancelling systems, large-radius turns may not involve enough steering wheel movement to trip the turn signal switch back to the neutral position automatically. However, if the self-cancelling system is configured to avoid this, it may tend to cancel the turn signal prematurely in response to normal steering wheel movement before and during common turns. Beginning in the late 1960s, indicating for a lane change was facilitated by the addition of a spring-loaded momentary signal-on position just shy of the left and right detents. The signal operates for however long the driver holds the lever partway towards the left or right turn signal detent. Some recent vehicles have an automatic lane-change indication feature; tapping the lever partway towards the left or right signal position and immediately releasing it causes the applicable turn indicators to flash three to five times.
Many transit bus
Transit bus
A transit bus , also known as a commuter bus, city bus, or public bus, is a bus used for short-distance public transport purposes...
es, such as those in New York
New York City Transit buses
New York City Transit buses, marked on the buses MTA New York City Bus, is a bus service that operates in all five boroughs of New York City, employing over 4300 buses on 219 routes within the five boroughs of New York City in the United States...
, have, since at least the 1950s, had turn signals activated by floor-mounted momentary-contact footswitches on the floor near the driver's left foot (on left-hand drive buses). The foot-activated signals allow bus drivers to keep both hands on the steering wheel while watching the road and scanning for passengers as they approach a bus stop. New York City Transit bus drivers, among others, are trained to step continuously on the right directional switch while servicing a bus stop, to signal other road users they are intentionally dwelling at the stop, allowing following buses to skip that stop. This method of signalling requires no special arrangements for self-cancellation or passing.
Turn signal colour
Federal Motor Vehicle Safety Standard 108
Federal Motor Vehicle Safety Standard 108 regulates all automotive lighting, signalling and reflective devices in the United States. Like all other Federal Motor Vehicle Safety Standards, FMVSS 108 is administered by the United States Department of Transportation's National Highway Traffic Safety...
took effect for the 1968 model year, whereupon amber became the only permissible front turn signal colour. Presently, almost all countries outside North America require that all front, side and rear turn signals produce amber
Amber (color)
Amber is an orange-yellow color that got its name from the material known as amber. Due to this, amber can refer not to one but to a series of shades of orange, since the natural material varies from nearly yellow when newer to orange or reddish-orange when older.-Amber:Amber is a pure chroma color...
light. In North America the rear signals may be amber or red. American regulators and other proponents of red rear turn signals have historically asserted there is no proven safety benefit to amber signals, though it has been recognised since the 1960s that amber turn signals are more quickly spotted than red ones. International proponents of amber rear signals say they are more easily discernible as turn signals, and U.S. studies in the early 1990s demonstrated improvements in the speed and accuracy of following drivers' reaction to stop lamps when the turn signals were amber rather than red. A 2008 U.S. study by the National Highway Traffic Safety Administration
National Highway Traffic Safety Administration
The National Highway Traffic Safety Administration is an agency of the Executive Branch of the U.S. government, part of the Department of Transportation...
(NHTSA) suggests vehicles with amber rear signals rather than red ones are up to 28% less likely to be involved in certain kinds of collisions, and a 2009 NHTSA study determined there is a significant overall safety benefit to amber rather than red rear turn signals.
There is some evidence that turn signals with colourless clear lenses and amber bulbs may be less conspicuous in bright sunlight than those with amber lenses and colourless bulbs.
Colour durability
The amber bulbs commonly used in turn signals with colourless lenses are no longer made with cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
glass, since cadmium was banned because of its toxicity by various regulations worldwide, including the European RoHS directive. Amber glass made without cadmium is relatively costly, so most amber bulbs are now made with clear glass dipped in an amber coating. Some of these coatings are not as durable as the bulbs themselves; with prolonged heat-cool cycles, the coating may flake off the bulb glass, or its colour may fade. This causes the turn signal to emit white light rather than the required amber light. The international regulation on motor vehicle bulbs requires manufacturers to test bulbs for colour endurance. However, no test protocol or colour durability requirement is specified. Discussion is ongoing within the Groupe des Rapporteurs d'Éclairage, the UNECE working group on vehicular lighting regulation, to develop and implement a colour durability standard. Rather than using an amber bulb, some signal lamps contain an inner amber plastic enclosure between a colourless bulb and the colourless outer lens. With the development of high power amber LED lights, it is possible that filament bulbs for turn signals will be made obsolete within a few years.
Sequential turn signals
Sequential turn signals are a feature on some cars
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
whereby multiple lights that produce the rear turn signal do not all flash on and off in phase. Rather, the horizontally arrayed lamps are illuminated sequentially: the innermost lamp lights and remains illuminated, the next outermost lamp lights and remains illuminated, followed by the next outermost lamp and so on until the outermost lamp lights briefly, at which point all lamps extinguish together and, after a short pause, the cycle begins again. The visual effect is one of outward motion in the direction of the intended turn or lane change. This implementation has generally been found only on American cars that use combination red rear stop and turn signal lamps.
Sequential turn signals were factory fitted to Ford Thunderbird
Ford Thunderbird
The Thunderbird , is an automobile manufactured by the Ford Motor Company in the United States over eleven model generations from 1955 through 2005...
s built between 1965 and 1971, inclusive, to Mercury Cougar
Mercury Cougar
The Mercury Cougar is an automobile which was sold under the Mercury brand of the Ford Motor Company's Lincoln-Mercury Division from 1967 to 2002. The name was first used in 1967 and was carried by a diverse series of cars over the next three decades. As is common with Mercury vehicles, the Cougar...
s between 1967 and 1973, to Shelby Mustang
Shelby Mustang
The Shelby Mustang is a high performance variant of the Ford Mustang which was built by Shelby American from 1965 through 1970. Following the introduction of the fifth generation Ford Mustang, the Shelby nameplate was revived in 2007 for new high performance versions of the Mustang.- 1965–1966 :The...
s between 1967 and 1970, to 1969 Imperial
Imperial (automobile)
Imperial was the Chrysler Corporation's luxury automobile brand between 1955 and 1975, with a brief reappearance in 1981 to 1983.The Imperial name had been used since 1926, but was never a separate make, just the top-of-the-line Chrysler. In 1955, the company decided to spin it off as its own make...
s (division of Chrysler
Chrysler
Chrysler Group LLC is a multinational automaker headquartered in Auburn Hills, Michigan, USA. Chrysler was first organized as the Chrysler Corporation in 1925....
Corp), to the JDM 1971 Nissan Cedric
Nissan Cedric
The Nissan Cedric is a large automobile produced by Nissan since 1960. It was developed to provide upscale transportation, competing with the Prince Skyline and Gloria which were later merged into the Nissan family...
, and to current Ford Mustang
Ford Mustang
The Ford Mustang is an automobile manufactured by the Ford Motor Company. It was initially based on the second generation North American Ford Falcon, a compact car. Introduced early on April 17, 1964, as a "1964½" model, the 1965 Mustang was the automaker's most successful launch since the Model A...
s. The system is costly and complex relative to standard turn signals, and no other production cars were so equipped.
Two different systems were employed. The earlier, fitted to the 1965 through 1968 Ford
Ford Motor Company
Ford Motor Company is an American multinational automaker based in Dearborn, Michigan, a suburb of Detroit. The automaker was founded by Henry Ford and incorporated on June 16, 1903. In addition to the Ford and Lincoln brands, Ford also owns a small stake in Mazda in Japan and Aston Martin in the UK...
-built cars, was electro-mechanical, featuring an electric motor
Electric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...
driving, through reduction gearing, a set of three slow-turning cam
Cam
A cam is a rotating or sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion or vice-versa. It is often a part of a rotating wheel or shaft that strikes a lever at one or more points on its circular path...
s. These cams would actuate switches to turn on the lights in sequence so long as the turn signal switch was set. This system was complicated and prone to failure, and the units no longer function in many surviving cars. Later Ford cars and the 1969 Imperial
Imperial (automobile)
Imperial was the Chrysler Corporation's luxury automobile brand between 1955 and 1975, with a brief reappearance in 1981 to 1983.The Imperial name had been used since 1926, but was never a separate make, just the top-of-the-line Chrysler. In 1955, the company decided to spin it off as its own make...
used a transistorised
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
control module with no moving parts.
FMVSS 108 has been officially interpreted as requiring all turn signal lights to illuminate simultaneously. However, the 2010 and newer Ford Mustang
Ford Mustang
The Ford Mustang is an automobile manufactured by the Ford Motor Company. It was initially based on the second generation North American Ford Falcon, a compact car. Introduced early on April 17, 1964, as a "1964½" model, the 1965 Mustang was the automaker's most successful launch since the Model A...
s are equipped with sequential turn signals.
Rear position lamps (tail lamps)
Night time vehicle conspicuity to the rear is provided by "rear position lamps" (also called "taillamps" or "tail lamps", "taillights" or "tail lights"). These are required to produce only red light, and to be wired such that they are lit whenever the front position lamps are illuminated—including when the headlamps are on. Rear position lamps may be combined with the vehicle's stop lamps, or separate from them. In combined-function installations, the lamps produce brighter red light for the stop lamp function, and dimmer red light for the rear position lamp function. The tail and stop light functions may be produced separately and/or by a dual-intensity lamp.Regulations worldwide stipulate minimum intensity ratios between the bright (stop) and dim (tail) modes, so that a vehicle displaying rear position lamps will not be mistakenly interpreted as showing stop lamps, and vice versa.
Many modern designs use LED lighting sources beginning in 1999 with the 2000 Cadillac Deville
Cadillac DeVille
The de Ville was originally a trim level and later a model of General Motors' Cadillac marque. The first car to bear the name was the 1949 Coupe de Ville, a prestige trim level of the Series 62 luxury coupe. The last model to be formally known as a de Ville was the 2005 Cadillac Deville, a...
.
Stop lamps (brake lights)
Red steady-burning rear lights, brighter than the rear position lamps, are activated when the driver applies the vehicle's brakeBrake
A brake is a mechanical device which inhibits motion. Its opposite component is a clutch. The rest of this article is dedicated to various types of vehicular brakes....
s. These are called "stop lamps", or, colloquially, "brake lights". They are required to be fitted in multiples of two, symmetrically at the left and right edges of the rear of every vehicle. Outside North America, the range of acceptable intensity for a stop lamp containing one light source (e.g. bulb) is 60 to 185 candelas. In North America, the acceptable range for a single-compartment stop lamp is 80 to 300 candelas.
Centre High Mount Stop Lamp (CHMSL)
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
since 1986, in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
and New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
since 1990, and in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
since 1998, a central brake lamp, mounted higher than the vehicle's left and right brake lamps and called a "Centre High Mount Stop Lamp (CHMSL)", is also required. The CHMSL is also sometimes referred to as the "centre brake lamp", the "third brake light", the "eye-level brake lamp", the "safety brake lamp", or the "high-level brake lamp". The CHMSL may produce light by means of a single central filament bulb, a row or cluster of filament bulbs or LED
LEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....
s, or a strip of Neon tube
Neon sign
Neon signs are made using electrified, luminous tube lights that contain rarefied neon or other gases. They are the most common use for neon lighting, which was first demonstrated in a modern form in December, 1910 by Georges Claude at the Paris Motor Show. While they are used worldwide, neon signs...
.
The CHMSL is intended to provide a deceleration warning to following drivers whose view of the vehicle's left and right stop lamps is blocked by interceding vehicles. It also helps to disambiguate brake vs. turn signal messages in North America, where red rear turn signals identical in appearance to stop lamps are permitted, and also can provide a redundant stop light signal in the event of a stop lamp malfunction.
The CHMSL is generally required to illuminate steadily and not permitted to flash, though U.S. regulators granted Mercedes-Benz
Mercedes-Benz
Mercedes-Benz is a German manufacturer of automobiles, buses, coaches, and trucks. Mercedes-Benz is a division of its parent company, Daimler AG...
a temporary, limited exemption to the steady-light requirement so as to evaluate whether a flashing CHMSL provides an emergency stop signal that effectively reduces the likelihood of a crash.
On passenger cars, the CHMSL may be placed above the back glass, affixed to the vehicle's interior just inside the back glass, or it may be integrated into the vehicle's deck lid or into a spoiler
Spoiler (automotive)
A spoiler is an automotive aerodynamic device whose intended design function is to 'spoil' unfavorable air movement across a body of a vehicle in motion. Spoilers on the front of a vehicle are often called air dams, because in addition to directing air flow they also reduce the amount of air...
. Other specialised fitments are sometimes seen; the Jeep Wrangler
Jeep Wrangler
The Jeep Wrangler is a subcompact four-wheel drive sport utility vehicle and an off-road vehicle manufactured by American automaker Chrysler, under its Jeep marque – and now in its fourth generation. It is a successor to the famous World War II 'Jeep' vehicle by way of the Willys civilian...
and Land Rover Freelander
Land Rover Freelander
The Land Rover Freelander is a compact crossover SUV made by Land Rover.The current generation is sold as the LR2 in North America and as the Freelander 2 in Europe...
have the CHMSL on a stalk fixed to the spare wheel carrier. Trucks, vans and commercial vehicles sometimes have the CHMSL mounted to the trailing edge of the vehicle's roof. The CHMSL is required by regulations worldwide to be centred laterally on the vehicle, though ECE R48 permits lateral offset of up to 15 cm if the vehicle's lateral centre is not coincident with a fixed body panel, but instead separates movable components such as doors. The Renault Master
Renault Master
Renault Master is the name used by French vehicle manufacturer Renault for its upper-medium size van — similar in size to the largest models of the more common Ford Transit....
van, for example, uses a laterally offset CHMSL for this reason. The height of the CHMSL is also regulated, in absolute terms and with respect to the mounting height of the vehicle's conventional left and right stop lamps. Depending on the left and right lamps' height, the lower edge of the CHMSL may be just above the left and right lamps' upper edge.
History
The 1952 Volkswagen Bus
Volkswagen Bus
-Light commercial vehicles:One of five generations of Volkswagen vans:*Volkswagen Type 2 , generation T1 *Volkswagen Type 2 , generation T2 *Volkswagen Type 2 , generation T3...
was equipped with a center-mounted brake light in addition to the two conventional brake lights. The 1968 - 1971 Ford Thunderbird
Ford Thunderbird
The Thunderbird , is an automobile manufactured by the Ford Motor Company in the United States over eleven model generations from 1955 through 2005...
could be ordered with optional supplemental high-mounted stop and turn signal lights integrated into the left and right interior trim surrounding the backglass. The Oldsmobile Toronado
Oldsmobile Toronado
The original Toronado began as a design painting by Oldsmobile stylist David North in 1962. His design, dubbed the "Flame Red Car," was for a compact sports/personal car never intended for production...
from 1971 to 1978, and the Buick Riviera
Buick Riviera
The Riviera by Buick is an automobile produced by Buick in the United States from the 1963 to 1999 model years, with 1,127,261 produced.A full-size coupé or personal luxury car, the early models of the Riviera in particular have been highly praised by automotive journalists and writers.A common...
from 1974 to 1976 had similar dual high-mounted supplemental stop/turn lights as standard equipment; these were located on the outside of the vehicle below the bottom of the backglass. This type of configuration was not widely adopted at the time. Auto and lamp manufacturers in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
experimented with dual high-mount supplemental stop lamps in the early 1980s, but this effort, too, failed to gain wide popular or regulatory support.
Early studies involving taxicab
Taxicab
A taxicab, also taxi or cab, is a type of vehicle for hire with a driver, used by a single passenger or small group of passengers, often for a non-shared ride. A taxicab conveys passengers between locations of their choice...
s and other fleet vehicles found that a third stop lamp reduced rear-end collisions by about 50%. The lamp's novelty probably played a role, since today the lamp is credited with reducing collisions by about 5%.
In 1986, the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
National Highway Traffic Safety Administration
National Highway Traffic Safety Administration
The National Highway Traffic Safety Administration is an agency of the Executive Branch of the U.S. government, part of the Department of Transportation...
and Transport Canada
Transport Canada
Transport Canada is the department within the government of Canada which is responsible for developing regulations, policies and services of transportation in Canada. It is part of the Transportation, Infrastructure and Communities portfolio...
mandated that all new passenger cars have a CHMSL installed. A CHMSL was required on all new light trucks and vans starting in 1994. CHMSLs are so inexpensive to incorporate into a vehicle that even if the lamps prevent only a few percent of rear end collisions they remain a cost-effective safety feature.
Emergency Stop Signal (ESS)
Toyota, Mercedes-Benz
Mercedes-Benz
Mercedes-Benz is a German manufacturer of automobiles, buses, coaches, and trucks. Mercedes-Benz is a division of its parent company, Daimler AG...
, Volvo
Volvo
AB Volvo is a Swedish builder of commercial vehicles, including trucks, buses and construction equipment. Volvo also supplies marine and industrial drive systems, aerospace components and financial services...
, and BMW
BMW
Bayerische Motoren Werke AG is a German automobile, motorcycle and engine manufacturing company founded in 1916. It also owns and produces the Mini marque, and is the parent company of Rolls-Royce Motor Cars. BMW produces motorcycles under BMW Motorrad and Husqvarna brands...
have released vehicles equipped to convey a special light signal when the vehicle is braked rapidly and severely. This is officially referred to as "Emergency Stop Signal", and ECE Regulation 48 calls for the lamps providing the ESS to flash at 4 Hz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
when a passenger car decelerates at greater than 6 m/s2 or a truck or bus decelerates at greater than 4 m/s2. Mercedes vehicles flash the stop lamps for the ESS, while vehicles from the Volkswagen
Volkswagen
Volkswagen is a German automobile manufacturer and is the original and biggest-selling marque of the Volkswagen Group, which now also owns the Audi, Bentley, Bugatti, Lamborghini, SEAT, and Škoda marques and the truck manufacturer Scania.Volkswagen means "people's car" in German, where it is...
Group of manufacturers (VW, Audi
Audi
Audi AG is a German automobile manufacturer, from supermini to crossover SUVs in various body styles and price ranges that are marketed under the Audi brand , positioned as the premium brand within the Volkswagen Group....
, SEAT
SEAT
SEAT, S.A. is a Spanish automobile manufacturer founded on May 9, 1950 by the Instituto Nacional de Industria , a state-owned industrial holding company....
& Skoda
Škoda Auto
Škoda Auto , more commonly known as Škoda, is an automobile manufacturer based in the Czech Republic. Škoda became a wholly owned subsidiary of the Volkswagen Group in 2000, positioned as the entry brand to the group...
) flash the hazard flashers.
Other methods of severe-braking indication have also been implemented; some Volvo models make the stop lamps brighter, and some BMWs have "Adaptive Brake Lights" that effectively increase the size of the stop lights under severe braking by illuminating the tail lamps at brighter-than-normal intensity. As long as the brighter-than-normal stop lamps are within the regulated maximum intensity for stop lamps in general, this kind of implementation does not require specific regulatory approval since the stop lamps are under all conditions operating in accord with the general regulations on stop lamps.
The idea behind such emergency-braking indicator systems is to catch following drivers' attention with special urgency. However, there remains considerable debate over whether the system offers a measurable increase in safety performance. To date, studies of vehicles in service have not shown any significant such improvement. The systems used by BMW, Volvo, and Mercedes differ not only in operational mode (growing vs. intensifying vs. flashing, respectively), but also in such parameters as deceleration threshold of activation. Data are being collected and analyzed in an effort to determine how such a system might be implemented to maximise a safety benefit, if such a benefit can be realised with visual emergency braking displays. An experimental study at the University of Toronto has tested stop lights which gradually and continuously grow in illuminated area with increasing vehicle deceleration rate (i.e., increasing brake application pressure).
One potentially problematic factor in the implementation of flashing stop lamps in North America is that North American regulations permit flashing stop lamps to be used in lieu of separate rear turn signal and hazard warning lamps.
Rear fog lamps
Fog
Fog is a collection of water droplets or ice crystals suspended in the air at or near the Earth's surface. While fog is a type of stratus cloud, the term "fog" is typically distinguished from the more generic term "cloud" in that fog is low-lying, and the moisture in the fog is often generated...
lamps" (or "fog taillamps"), which serve as high-intensity rear position lamps to be energised by the driver in conditions of poor visibility to enhance vehicle conspicuity from the rear. The allowable range of intensity for a rear fog lamp is 150 to 300 candelas, which is within the range of a U.S. stop lamp. For this reason, some European vehicles imported to the United States have their rear fog lamps wired as stop lamps, since their European-specification stop lamps may not be sufficiently intense to comply with U.S. regulations, and in North America rear fog lamps are not required equipment. However, they are permitted, and are found almost exclusively on European-brand vehicles in North America — Audi, Jaguar, Mercedes, MINI, Land Rover, Porsche, Saab and Volvo provide functional rear fog lights on their North American models. The final generation Oldsmobile Aurora
Oldsmobile Aurora
The Oldsmobile Aurora was a full-size sports sedan made by the Oldsmobile division of General Motors and launched in 1995. The Aurora rode on the same Cadillac-derived G platform as the 2-door Buick Riviera....
also had dual rear fog lights installed in the rear bumper as standard equipment.
Most jurisdictions permit rear fog lamps to be installed either singly or in pairs. If a single rear fog is fitted, most jurisdictions require it to be located at or to the driver's side of the vehicle's centreline — whichever side is the prevailing driver's side in the country in which the vehicle is registered. This is to maximise the sight line of following drivers to the rear fog lamp. In many cases, a single reversing lamp is mounted on the passenger side of the vehicle, positionally symmetrical with the rear fog. If two rear fog lamps are fitted, they must be symmetrical with respect to the vehicle's centreline. Proponents of twin rear fog lamps say two lamps provide vehicle distance information not available from a single lamp. Proponents of the single rear fog lamp say dual rear fog lamps closely mimic the appearance of illuminated stop lamps (which are mandatorily installed in pairs), reducing the conspicuity of the stop lamps' message when the rear fogs are activated. To provide some safeguard against rear fog lamps being confused with stop lamps, ECE R48 requires a separation of at least 10 cm between the closest illuminated edges of any stop lamp and any rear fog lamp.
Reversing lamps
Rear registration plate lamp
The rear registration plate is illuminated by a white lamp designed to light the surface of the plate without creating white light directly visible to the rear of the vehicle; it must be illuminated whenever the position lamps are lit.On large vehicles
Large vehicles such as trucksTruck
A truck or lorry is a motor vehicle designed to transport cargo. Trucks vary greatly in size, power, and configuration, with the smallest being mechanically similar to an automobile...
and buses
Bus
A bus is a road vehicle designed to carry passengers. Buses can have a capacity as high as 300 passengers. The most common type of bus is the single-decker bus, with larger loads carried by double-decker buses and articulated buses, and smaller loads carried by midibuses and minibuses; coaches are...
are in many cases required to carry additional lighting devices beyond those required on passenger vehicles. The specific requirements vary according to the regulations in force where the vehicle is registered and/or operated.
Identification lamps
In North America, vehicles over 2,032 mm (80 inches) wide must be equipped with three amber front and three red rear identification lamps spaced between 6 and 12 inches apart at the center of the front and rear of the vehicle, as high as practicable. The front identification lamps are typically mounted atop the cab of vehicles that do not have a flat-nose design. This type of identification lamp can also be found on road trainsRoad train
A road train or roadtrain is a trucking concept used in remote areas of Argentina, Australia, Mexico, the United States and Canada to move freight efficiently. The term "road train" is most often used in Australia. In the U.S. and Canada the terms "triples," "turnpike doubles" and "Rocky Mountain...
in Australia.
Clearance lamps
In North America, vehicles over 2,032 mm (80 inches) wide must be equipped with left and right amber front and red rear clearance lights to indicate the overall width of the vehicle. These must be amber at the front, red at the rear, and mounted as high as practicable.End outline marker lamps
ECE Regulations require large vehicles to be equipped with left and right white front and red rear end outline marker lamps, which serve a purpose similar to that of the American clearance lamp.Intermediate sidemarker lamps & reflectors
North American regulations require large vehicles to be equipped with left and right amber sidemarker lights and reflectors mounted midway between the front and rear sidemarkers.Rear overtake lights
Until about the 1970s in France, Spain, Morroco, and possibly other countries, many commercial vehicles and some soviet road trains from "Sovtransavto" had a green light mounted on the rear offside. This could be operated by the driver to indicate that it was safe for the following vehicle to overtake.Hazard flashers
Also called "hazards", "hazard warning flashers", "hazard warning lights", "4-way flashers", or simply "flashers". International regulations require vehicles to be equipped with a control which, when activated, flashes the left and right directional signals, front and rear, all at the same time and in phase. This function is meant to indicate a hazard such as a vehicle stopped in or near moving traffic, a disabled vehicle, a vehicle moving substantially slower than the flow of traffic such as a truck climbing a steep grade, or the presence of stopped or slow traffic ahead on a high speed road. Sometimes, they are used in severe fog conditions. Operation of the hazard flashers must be from a control independent of the turn signal control, and an audiovisual tell-taleTell-tale (automotive)
A tell-tale is an indicator of the status or malfunction of a system within a motor vehicle. Tell-tales consist of a light bulb or an LED which lights up a symbol or text legend...
must be provided to the driver. In vehicles with a separate left and right green turn signal tell-tale on the dashboard, both left and right indicators may flash to provide visual indication of the hazard flashers' operation. In vehicles with a single green turn signal tell-tale on the dashboard, a separate red tell-tale must be provided for hazard flasher indication. Because the hazard flasher function operates the vehicle's left and right turn signals, a left or a right turn signal function cannot be provided while the hazard flashers are operating.
Retroreflectors
| Red rear sidemarker retroreflectors on Ford F-series Ford F-Series The F-Series is a series of full-size pickup trucks from Ford Motor Company which has been sold continuously for over six decades. The most popular variant of the F-Series is the F-150... trucks without (top) and with (bottom) direct illumination |
"Retroreflector
Retroreflector
A retroreflector is a device or surface that reflects light back to its source with a minimum scattering of light. An electromagnetic wave front is reflected back along a vector that is parallel to but opposite in direction from the wave's source. The device or surface's angle of incidence is...
s" (also "reflex reflectors") produce no light of their own, but rather reflect incident light back towards its source, e.g., another driver's headlight. They are regulated as automotive lighting devices, and specified so as to account for the separation between a vehicle's headlamps and its driver's eyes. Thus, vehicles are conspicuous even when their electrically powered lighting system is off or disabled. Regulations worldwide require each vehicle to be equipped with rear-facing red retroreflectors. Since 1968 North American regulations also require side-facing retroreflectors, amber in front and red in the rear. Sweden, South Africa and other countries have at various times required white front-facing retroreflectors.
Multicolour auxiliary signals
Some jurisdictions, such as the US states of OregonOregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
and Idaho
Idaho
Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....
, permit vehicles to be equipped with auxiliary rear signal systems displaying green light when the accelerator is depressed, yellow light when the vehicle is coasting, and red light when the brake is depressed.
Such systems have in the past been sold as aftermarket
Aftermarket (automotive)
The automotive aftermarket is the secondary market of the automotive industry, concerned with the manufacturing, remanufacturing, distribution, retailing, and installation of all vehicle parts, chemicals, tools, equipment and accessories for light and heavy vehicles, after the sale of the...
accessories, but are today seldom seen in traffic.
Research and development
The US National Highway Traffic Safety AdministrationNational Highway Traffic Safety Administration
The National Highway Traffic Safety Administration is an agency of the Executive Branch of the U.S. government, part of the Department of Transportation...
, among other bodies, has commissioned studies of these and many other vehicle signal systems and configurations, in an effort to determine the most promising avenues and best practices for enhanced crash avoidance via optimised vehicle conspicuity and signal lighting systems.
Convenience lights
Most cars have at least one "dome light" (UK, courtesy light) located in or near the ceiling of the passenger compartment, to provide illumination by which to fasten seatbelts and enter or exit the car. These often have an option to switch on when the front (or any) passenger doors are opened. Many vehicles have expanded this feature, causing the overhead interior light to remain on after all doors are closed, allowing passengers to fasten seat belts with added illumination. The extended lighting cycle usually ends when the vehicles ignition has begun, or a gradual reduction in light emitted after a couple of minutes if the car isn't started, called "theater" lighting. Interior lighting has been added on some vehicles at the bottom edge of the dashboard, which illuminate the floor for front passengers (which are referred to in the US as "courtesy lights"), or underneath the front seats at the rear, to illuminate the floor for rear seat passengers. This type of convenience lighting approach is also sometimes used to illuminate interior or exterior door handles, exterior step running boards, or electric window switches.LED light sources are beginning to appear increasingly as interior convenience lights in various locations as the technology becomes more widely used, especially with finely focused lighting on console control surfaces and in cabin storage areas.
There may be additional map
Map
A map is a visual representation of an area—a symbolic depiction highlighting relationships between elements of that space such as objects, regions, and themes....
lights that are aimed at specific passenger positions, that allow for reading without particular glare distraction to the driver. Some vehicles have "approach lighting" (puddle lights) integrated into the exterior mirrors or lower edges of the doors, as well as activating interior lighting, that is activated via key fob. Many cars have lights in the trunk
Trunk (automobile)
The trunk or boot of an automobile or car is the vehicle's main storage, luggage, or cargo compartment. Trunk is used in North American English and Jamaican English; boot is used elsewhere in the English speaking world. Trunk is also primarily used in many non-English speaking regions, such as...
(or boot), the engine compartment, and the glovebox
Glove compartment
A glove compartment or glovebox, also known as a little cupboard, is a compartment built into the dashboard, located over the front-seat passenger's footwell in an automobile, often used for miscellaneous storage. The name derives from the original purpose of the compartment, to store gloves...
and other storage compartments.
Most instruments and controls on a dashboard
Dashboard
A dashboard is a control panel placed in front of the driver of an automobile, housing instrumentation and controls for operation of the vehicle....
in modern vehicles are illuminated in some fashion when the headlamps are turned on, and the intensity of light can be adjusted by the driver for comfort. Saabs feature an aerospace technologies-derived "night panel" function which shuts off all interior illumination save for the speedometer (unless attention is called to a critical situation on another gauge) to improve the driver's night vision.
Emergency vehicle lights
Emergency vehicle
An emergency vehicle is any vehicle that is designated and authorized to respond to an emergency. These vehicles are usually operated by designated agencies, often part of the government, but also run by charities, non-governmental organizations and some commercial companies...
s such as fire engines, ambulance
Ambulance
An ambulance is a vehicle for transportation of sick or injured people to, from or between places of treatment for an illness or injury, and in some instances will also provide out of hospital medical care to the patient...
s, police car
Police car
A police car is a ground vehicle used by police, to assist with their duties in patrolling and responding to incidents. Typical uses of a police car include transportation for officers to reach the scene of an incident quickly, to transport criminal suspects, or to patrol an area, while providing a...
s, snow-removal vehicles
Snowplow
A snowplow is a device intended for mounting on a vehicle, used for removing snow and ice from outdoor surfaces, typically those serving transportation purposes...
and tow truck
Tow truck
A tow truck is a vehicle used to transport motor vehicles to another location , or to recover vehicles which are no longer on a drivable surface.Towing services are generally provided by an emergency road service operator...
s are usually equipped with intense warning lights of particular colours. These may be motorised rotating beacons, xenon strobes, or arrays of LED
LEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....
s. The prescribed colours differ by jurisdiction; in most countries, blue and/or red special warning lamps are used on police, fire, and medical-emergency vehicles. In North America and some other jurisdictions, amber lights are for tow trucks, private security personnel, construction vehicles, and other nonofficial special-service vehicles, while volunteer firefighters use red, blue, or green, depending on jurisdiction. In the UK, doctors may use green warning lamps. Special warning lights, usually amber, are also sometimes mounted on slow vehicles such as mobile crane
Mobile crane
-Defination:Mobile Crane A cable-controlled crane mounted on crawlers or rubber-tired carriers. A hydraulic-powered crane with a telescoping boom mounted on truck-type carriers or as self-propelled models..-History:...
s, excavator
Excavator
Excavators are heavy construction equipment consisting of a boom, stick, bucket and cab on a rotating platform . The house sits atop an undercarriage with tracks or wheels. A cable-operated excavator uses winches and steel ropes to accomplish the movements. They are a natural progression from the...
s, tractor
Tractor
A tractor is a vehicle specifically designed to deliver a high tractive effort at slow speeds, for the purposes of hauling a trailer or machinery used in agriculture or construction...
s, and even mobility scooter
Mobility scooter
A mobility scooter is a mobility aid equivalent to a wheelchair but configured like a motorscooter. It is often referred to as a power-operated vehicle/scooter or electric scooter as well.-Description:...
s in certain conditions.
Taxi displays
TaxicabTaxicab
A taxicab, also taxi or cab, is a type of vehicle for hire with a driver, used by a single passenger or small group of passengers, often for a non-shared ride. A taxicab conveys passengers between locations of their choice...
s are distinguished by special lights according to local regulations.
They may have an illuminated "Taxi" sign, a light to signal that they are ready to take passengers or off duty, and/or an emergency panic light the driver can activate in the event of a robbery to alert passersby to call the police.
Construction and technology
Non-halogen
Traditionally, an tungsten
Tungsten
Tungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...
incandescent light bulb
Incandescent light bulb
The incandescent light bulb, incandescent lamp or incandescent light globe makes light by heating a metal filament wire to a high temperature until it glows. The hot filament is protected from air by a glass bulb that is filled with inert gas or evacuated. In a halogen lamp, a chemical process...
has been the light source used in all of the various automotive signalling and marking lamps. Typically, bulbs of 21 to 27 watt
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
s, producing 280 to 570 lumens
Lumen (unit)
The lumen is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a source. Luminous flux differs from power in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light, while radiant flux...
(22 to 45 mean spherical candlepower
Candlepower
Candlepower is a now-obsolete unit which was used to express levels of light intensity in terms of the light emitted by a candle of specific size and constituents...
) are used for stop, turn, reversing and rear fog lamps, while bulbs of 4 to 10 W, producing 40 to 130 lm
Lumen (unit)
The lumen is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a source. Luminous flux differs from power in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light, while radiant flux...
(3 to 10 mscp) are used for tail lamps, parking lamps, sidemarker lamps and side turn signal repeaters. These bulbs typically have either a metal bayonet base
Bayonet mount
A bayonet mount or bayonet connector is a fastening mechanism consisting of a male side with one or more pins, and a female receptor with matching L slots and spring to keep the two parts locked together....
or a plastic or glass wedge base
Wedge base
A wedge base is a type of electrical connector used as a fitting for small light bulbs. It is similar to the bi-pin connector, except that the two "pins" are the same wires that extend into the bulb , and the wires are bent up onto the sides of the base, where they make contact with the socket...
for the physical and electrical interface with the lamp socket.
Halogen
Tungsten-halogen light bulbs are a very common light source for headlamp
Headlamp
A headlamp is a lamp, usually attached to the front of a vehicle such as a car or a motorcycle, with the purpose of illuminating the road ahead during periods of low visibility, such as darkness or precipitation. Headlamp performance has steadily improved throughout the automobile age, spurred by...
s and other forward illumination functions. Some recent-model vehicles use small halogen bulbs for exterior signalling and marking functions, as well. The first halogen lamp approved for automotive use was the H1
H1 bulbs
The H1 is a halogen lamp designed for use in automotive headlamps and fog and driving lamps. It has also been widely applied in emergency vehicle lights.-Origin:...
, which was introduced in Europe in 1962.
Xenon
The devices popularly called "Xenon headlamps" are formally known as high-intensity discharge, or HID lamps.Xenon is currently the lamp used in single-source lighting systems being developed for automotive use. In these systems, a single light source sends light via optical fibers to wherever it is needed in the automobile. This development, known as distributive lighting, is already appearing in the interior lighting features, for example the Ford Mustang's interior lighting. In an expanded system, the light could be channeled to the side mirrors for example, which would act as forward driving lights that could be made to swivel in position with the car as it turns. The headlight pattern would not be limited to individual overlapping beams, but could be channeled by electronic controls of the fiber optics to provide optimum visibility over an extended range of driving conditions including fog, dust or snow. Individual lamps would not be needed, just a mounting point for the optical fibers running back to the single light source and computer controlled for colour, intensity and continuity.
Neon tubes
Neon lampNeon lamp
A neon lamp is a miniature gas discharge lamp that typically contains neon gas at a low pressure in a glass capsule. Only a thin region adjacent to the electrodes glows in these lamps, which distinguishes them from the much longer and brighter neon tubes used for signage...
tubes were introduced into widespread production for the CHMSL on the 1995 Ford Explorer
Ford Explorer
The Ford Explorer is a sport-utility vehicle sold in North America and built by the Ford Motor Company since 1990, as a replacement for the smaller but related Ford Bronco II. It is manufactured in Chicago, Illinois...
, and notable later uses included the 1998 Lincoln Mark VIII
Lincoln Mark VIII
The Lincoln Mark VIII is a large, rear-wheel drive grand touring luxury coupe built from 1993 to 1998. It was the successor of the Mark VII. The Mark VIII was built at Ford's Wixom, Michigan assembly plant and was based on the FN10 platform, a relative of the MN12 platform which underpinned the...
, with a neon tube spanning the width of the trunk decklid, and the BMW Z8
BMW Z8
The BMW Z8 was a roadster car produced by German automaker BMW from 1999-2003. It was given the E52 BMW model code.The Z8 was the production variant of the 1997 Z07 concept car, which was designed by Henrik Fisker at BMW's DesignworksUSA in Southern California. The Z07 originally was designed as a...
, which made extensive use of neon. Numerous concept cars have included neon lamp features, from such manufacturers as Volvo
Volvo
AB Volvo is a Swedish builder of commercial vehicles, including trucks, buses and construction equipment. Volvo also supplies marine and industrial drive systems, aerospace components and financial services...
. Hella
Hella (company)
Hella KGaA Hueck & Co. is an internationally operating German automotive part supplier with headquarters in Lippstadt, North Rhine-Westphalia. Core businesses are vehicle lighting and electronics systems and components. Hella is also involved in the areas of vehicle diagnostics and thermal...
offered an aftermarket neon CHMSL in the late 1990s.
The linear packaging of the neon light source lends itself to the linear packaging favored for many CHMSL installations, and neon lights offer the same nearly instant rise time benefit as LEDs. However, neon tubes require an expensive and relatively power-hungry ballast (power supply unit), and as a result, neon lights have not found significant long-term popularity as sources of light for automotive signaling.
Light emitting diodes (LED)
LEDLEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....
s are being used with increasing frequency in automotive lamps. They offer very long service life
Mean time between failure
Mean time between failures is the predicted elapsed time between inherent failures of a system during operation. MTBF can be calculated as the arithmetic mean time between failures of a system. The MTBF is typically part of a model that assumes the failed system is immediately repaired , as a...
, extreme vibration resistance, and can permit considerably shallower packaging compared to most bulb-type assemblies. LEDs also offer a significant safety performance benefit when employed in stop lights, for when power is applied they rise to full intensity approximately 200 milliseconds (0.2 seconds) faster than incandescent bulbs. This fast rise time
Rise time
In electronics, when describing a voltage or current step function, rise time refers to the time required for a signal to change from a specified low value to a specified high value...
not only improves the attentional conspicuity of the stop lamp, but also provides following drivers with increased time in which to react to the appearance of the stop lamps.
LEDs were first applied to automotive lighting in Centre High Mount Stop Lamps (CHMSL), beginning in the late 1980s. Adoption of LEDs for other signal functions on passenger cars has been slow, but is beginning to increase with demand for the technology and related styling updates. The 2007 Audi R8 sports car uses two strips of optically-focused high-intensity LEDs for its Daytime Running Lamps
Daytime running lamp
A daytime running lamp is an automotive lighting device on the front of a roadgoing motor vehicle, installed in pairs, automatically switched on when the vehicle is moving forward, emitting white, yellow, or amber light to increase the conspicuity of the vehicle during daylight...
. Optional on the R8 in ECE markets is the world's first LED headlamp made by AL-Automotive Lighting. The low and high beams along with the position (parking) lamp and front turn signal are all realised with LEDs. The Lexus LS 600h features LED low beam, position and sidemarker lamps in North America, and the 2009 Cadillac Escalade
Cadillac Escalade
The Cadillac Escalade is a full-size luxury sport utility vehicle sold by the General Motors luxury brand, Cadillac. It was the division's first major entry into the popular SUV market. The Escalade was introduced for the 1999 model year in response to German and Japanese competitors and to Ford's...
Platinum uses LEDs for the low and high beams, as well as for the position and sidemarker lamps.
The commercial vehicle industry has rapidly adopted LEDs for virtually all signaling and marking functions on trucks and buses, because in addition to the fast rise time and concomitant safety benefit, LEDs' extremely long service life reduces vehicle downtime. Almost all commercial vehicles use exterior lighting devices of standardised format and fitment, which has cost-reduced and sped the changeover.
LED lamps have been proven to be a feasible alternative to traditional light sources for flashing beacon lights on vehicles such as maintenance trucks. Previously, traditional light sources required the engine to continue running to ensure that the battery would not get worn out if the lights were to be used for more than a few hours. The energy-efficient nature of the LED source allows the engine to remain turned off but the light to continue to flash.
Variable-intensity signal lamps
Internationalised ECE regulationsWorld Forum for Harmonization of Vehicle Regulations
The World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe...
explicitly permit vehicle signal lamps with intensity automatically increased during bright daylight hours when sunlight reduces the effectiveness of the stop lamps, and automatically decreased during hours of darkness when glare could be a concern. Both US and ECE regulations contain provisions for determining the minimum and maximum acceptable intensity for lamps that contain more than a single light source.
See also
- Automotive lamp typesAutomotive lamp typesA modern vehicle uses different kinds of lamps for multiple purposes: illumination for the driver to be able to drive in dark conditions, illumination to be seen and lights for information displays. Types of these lamps vary depending on the purpose and different car manufacturers and models use...
- Daytime running lampDaytime running lampA daytime running lamp is an automotive lighting device on the front of a roadgoing motor vehicle, installed in pairs, automatically switched on when the vehicle is moving forward, emitting white, yellow, or amber light to increase the conspicuity of the vehicle during daylight...
- Twilight SentinelTwilight SentinelOn an automobile, Twilight Sentinel is a device on General Motors' cars that senses outside light and turns the exterior lights on and off depending on lighting conditions....
- Federal Motor Vehicle Safety Standard 108Federal Motor Vehicle Safety Standard 108Federal Motor Vehicle Safety Standard 108 regulates all automotive lighting, signalling and reflective devices in the United States. Like all other Federal Motor Vehicle Safety Standards, FMVSS 108 is administered by the United States Department of Transportation's National Highway Traffic Safety...
- Florence Lawrence - inventor of the first turn and stop signals
- HeadlampHeadlampA headlamp is a lamp, usually attached to the front of a vehicle such as a car or a motorcycle, with the purpose of illuminating the road ahead during periods of low visibility, such as darkness or precipitation. Headlamp performance has steadily improved throughout the automobile age, spurred by...
- Hidden headlampsHidden headlampsHidden headlamps, also commonly known as pop-up headlamps or headlights, are an automotive styling feature that conceals an automobile's headlamps when they are not in use...
- Lighting-up timeLighting-up timeIn the United Kingdom there is a legally enforced lighting-up time, defined as from one half-hour after sunset to one half-hour before sunrise, during which all motor vehicles on unlit public roads must use their headlights....
- National Highway Traffic Safety AdministrationNational Highway Traffic Safety AdministrationThe National Highway Traffic Safety Administration is an agency of the Executive Branch of the U.S. government, part of the Department of Transportation...
(NHTSA) - Turn indicator stalk
- Windscreen wiperWindscreen wiperA windscreen wiper or windshield wiper is a device used to remove rain and debris from a windscreen or windshield. Almost all motor vehicles, including trains, aircraft and watercraft, are equipped with such wipers, which are usually a legal requirement.A wiper generally consists of an arm,...
- World Forum for Harmonization of Vehicle RegulationsWorld Forum for Harmonization of Vehicle RegulationsThe World Forum for Harmonization of Vehicle Regulations is a working party of the United Nations Economic Commission for Europe...
External links
- Sidemarkers, flashing and non-flashing
- Turn signal patent, issued 1909
- Car Lights Flash Warning Signals 1951 article on first Hazard Flashers