A daytime running lamp (DRL, also daylight running lamp or daytime running light) 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 conditions. DRLs might have been first seriously proposed in 1961 in the USA, in response to Texas then-Governor Price Daniels' drive-safely campaign.^[1].

[edit] Implementations

full-voltage vs. reduced-voltage (DRL) operation of low beam headlamp on European-market Volkswagen

Depending on prevailing regulations and vehicle equipment, the daytime running light function may be implemented by functionally-specific lamps, by operating the low-beam headlamps or fog lamps at full or reduced intensity, by operating the high-beam headlamps at reduced intensity, or by steady-burning operation of the front turn signals. Compared to any mode of headlamp operation to create the daytime running light, functionally-dedicated DRLs maximize the potential benefits in safety performance and minimize fuel consumption, glare, motorcycle masking, and other potential drawbacks.^[2]

[edit] Safety performance

Numerous studies done worldwide since the 1970s have tended to demonstrate that daytime running lights improve safety.^[3][2][4]. However, the U.S. National Highway Traffic Safety Administration has stated that DRLs have had no significant safety benefit in the U.S. and may have reduced safety in some cases.^[5]

[edit] Effect of ambient light

The Daytime Running Light was first mandated, and safety benefits first perceived, in Scandinavian countries where it is frequently and persistently dark during daytime hours. As ambient light levels increase, the potential safety benefit decreases while the DRL intensity required for a safety improvement increases. The safety benefit produced by DRLs in relatively dark Nordic countries is roughly triple the benefit observed in relatively bright Israel and America.^[2]

[edit] Effect on motorcycle safety

In many countries, every motorcycle's low beam headlamp has been wired to illuminate whenever the engine is running, either as a matter of law or of voluntary industry practice. Some motorcycling advocacy groups are concerned over the potential for reduced motorcycle conspicuity with the introduction of headlamp-based DRLs on cars and other dual-track vehicles, since it means motorcycles are no longer the only vehicles displaying headlamps during the day.^[6]. Some researchers have suggested that amber DRLs be reserved for use exclusively on motorcycles, in countries where amber is not presently a permissible color for DRLs on any vehicles,^[7] while other research has concluded there is no safety benefit to DRLs on motorcycles.^[8]

[edit] Environmental impact

LED daytime running lights on Audi A4

DRL power consumption varies widely depending on the implementation. Current production DRL systems consume from 8 watts (dedicated LED system) to over 200 W (headlamps and all parking, tail, and marker lights on). International regulators, primarily in Europe, are working to balance the potential safety benefit offered by DRL with the increased fuel consumption due to their use. Because the power to run the DRLs must be produced by the engine, which in turn requires burning additional fuel, high-power DRL systems increase CO₂ emissions sufficiently to affect a country's compliance with the Kyoto protocol on greenhouse gas emissions.^[9] For that reason, low-power solutions are being encouraged^[10] for use when and if DRLs become mandatory in ECE Regulations. LEDs and low-power, high-efficacy, long-life light bulbs produce appropriate amounts of light for an effective DRL without significantly increasing fuel consumption or emissions. Fuel consumption reductions of up to 0.5 mpg may be found when comparing a 55 W DRL system to a 200&nbspW DRL system.^[11] In 2006, the UK's Department of Transport also found significant reductions in emissions and fuel consumption when comparing a 42 W DRL system to a 160 W full headlight DRL systems.^[12] DRL fuel consumption can be reduced to insignificant levels by the use of 8- to 20 W DRL systems based on LEDs or high-efficacy filament bulbs.

[edit] Worldwide

[edit] Scandinavia

Hella DRL retrofit kit offered in Sweden in the 1970s. Package text reads "Install Hella perception lights so you are seen in traffic".

DRLs were first mandated in Scandinavian countries, where ambient light levels in the winter are generally low even during the day. Sweden was the first country to require widespread DRLs in 1977. At the time, the function was known as varselljus ("perception light" or "notice light"). The initial regulations in these countries favored devices incorporating 21-watt signal bulbs identical to those used in brake lamps and turn signals, producing yellow or white light of approximately 400 to 600 candelas on axis, mounted at the outer left and right edges of the front of the vehicle. Finland adopted a daytime-light requirement in 1972 on rural roads in wintertime, and in 1982 on rural roads in summertime and 1997 on all roads all year long; Norway in 1986, Iceland in 1988, and Denmark in 1990. To increase manufacturer flexibility in complying with the requirement for DRLs, the daytime illumination of low-beam headlights was added as an optional implementation. Given the ECE headlamp specifications in use in those countries, such an implementation would produce approximately 450 cd axially.

[edit] United Kingdom

UK national regulations required vehicles first used on or after 1 April 1987 to be equipped with a dim-dip device or daytime 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 percent and 20 percent of normal low-beam intensity when the position lamps are switched on, the primary aim being to prevent drivers using only position lamps at night. UK specifications for functionally-dedicated DRLs called for at least 200 candelas straight ahead, and no more than 800 candelas in any direction. These regulatory provisions were based on ILPE research and recommendations. In practice, most vehicles were equipped with the dim-dip option, rather than DRLs, and the Dim-Dip requirement was quashed by the European Commission. See Automotive lighting for more information.

[edit] European Union

Hella 6w halogen-bulb DRLs for retrofit. Other retrofit DRLs use LEDs

Germany, France and others have encouraged or required daytime use of low-beam headlamps on certain roads at certain times of year, Ireland encourages and Bulgaria requires the use of low-beam headlights at all times during winter, Italy, Hungary and Romania require daytime running lamps outside populated areas, and Czech Republic, Estonia, Lithuania and Slovakia require the use of full or reduced voltage low-beam headlights at all times. Most EU states no longer significantly disagree over whether DRLs should be required, permitted, or prohibited; by member-state consensus, from 2011, ECE R48 will require DRLs conforming to ECE R87 (or full-time low-beam headlamps) on all new motor vehicles^[13][14]. DRLs compliant with R87 emit white light of between 400 and 1200 candelas.^[15]

[edit] Canada

Canada Motor Vehicle Safety Standard 108 requires DRLs on all new vehicles made or imported after January 1, 1990. Canada's proposed DRL regulation was essentially similar to regulations in place in Scandinavia, with an axial luminous intensity limit of 1,500 candelas, but automakers objected, claiming it was too expensive to add a new front lighting device, and would increase warranty costs (by dint of increased bulb replacements) to run the low beams. After a pitched regulatory battle, the standard was rewritten to permit the use of reduced-voltage high beam headlamps producing up to 7,000 axial candelas, as well as permitting any light color from white to amber or selective yellow. These changes to the regulation permitted automakers to implement a less-costly DRL, such as by connecting the high beam filaments in series to supply each filament with half its rated voltage, or by burning the front turn signals full time except when they are actually flashing as turn indicators.

Reduced-voltage high beam DRL on a US/Canada 2002 Lexus RX300

[edit] United States

General Motors, interested in reducing the build variations of cars for the North American market, began lobbying the DOT (United States Department of Transportation) to permit DRLs in the United States shortly after Canada required them. A prolonged regulatory battle was fought, with the DOT objecting on grounds of potential safety drawbacks and glare issues. Eventually, however, these objections were set aside and DRLs of the same types allowed in Canada (save for fog lamp DRLs) were legalized but not mandated effective with the 1995 model year. General Motors immediately equipped most (and, in following years, all) of its vehicles with DRLs beginning with the Chevrolet Corsica. Saab, Volkswagen, Volvo, Suzuki and Subaru gradually introduced DRLs in the U.S. market beginning in 1995. In recent years, Lexus has installed high-beam or turn signal based DRLs on US models. Some Toyota models come with DRLs as standard or optional equipment, and with a driver-controllable on/off switch. Starting in the 2006 model year, Honda began equipping their U.S. models with DRLs, mostly by reduced-intensity operation of the high beam headlamps.

Public reaction to DRLs, generally neutral to positive in Canada, is decidedly mixed in the U.S. Thousands of complaints regarding glare from DRLs were lodged with the DOT shortly after DRLs were permitted on cars, and there was also concern that headlamp-based DRLs reduce the conspicuity of motorcycles, and that DRLs based on front turn signals introduce ambiguity into the turn signal system. In 1997, in response to these complaints and after measuring actual DRL intensity well above the 7,000 cd limit on vehicles in use, DOT proposed changes to the DRL specification that would have capped axial intensity at 1,500 candelas, a level nearly identical to the European 1,200 cd and identical to the initially-proposed Canadian limit. During the open comment period, thousands of public comments were received by DOT in support of lowering the intensity (or advocating the complete elimination of DRLs from U.S. roads). Automaker sentiment generally ran along predictable lines, with European automakers experienced at complying with European DRL requirements voicing no objection to the proposal, and North American automakers vociferously repeating the same objections they raised in response to Canada's initial proposal.^[16][17] The DOT proposal for DRL intensity reduction was rescinded in 2004.^[18]

[edit] Australia

DRLs are permitted but not required in Australia, though Australian automotive authorities are interested in introducing DRL requirements.^[19]

[edit] References

[edit] See also

• Automotive lighting
• Automobile safety