Daytime running lamp
A daytime running lamp is an automotive lighting and bicycle lighting device on the front of a road going motor vehicle or bicycle. It is automatically switched on when the vehicle's handbrake has been pulled down, when the vehicle is in gear, or when the engine is started, emitting white, yellow, or amber light. Their intended use is not to help the driver see the road or their surroundings, but to help other road users identify an active vehicle.
Implementations
Depending on prevailing regulations and equipment, vehicles may implement the daytime-running light function by functionally turning on specific lamps, by operating low-beam headlamps or fog lamps at full or reduced intensity, by operating high-beam headlamps at reduced intensity, or by steady-burning operation of the front turn signals. Compared to any mode of headlamp operation to produce the daytime running light, functionally dedicated DRLs maximize the potential benefits in safety performance, glare, motorcycle masking, and other potential drawbacks.Usage
A daytime running lamp is usually automatically switched on once the ignition is on; other vehicles may switch the daytime running lamps on when the parking brake is released or when the vehicle is shifted into gear. A daytime running lamp emits a brighter light when the headlamps are not turned on and its brightness will be dimmed slightly in conjunction with the headlamps being turned on.Safety performance
A 2008 study by the US National Highway Traffic Safety Administration analysed the effect of DRLs on frontal and side-on crashes between two vehicles and on vehicle collisions with pedestrians, cyclists, and motorcyclists. The analysis determined that DRLs offer no statistically significant reduction in the frequency or severity of the collisions studied, except for a reduction in light trucks' and vans' involvement in two-vehicle crashes by a statistically significant 5.7%.Effect of ambient light
The daytime running light was first mandated, and safety benefits first perceived, in Scandinavian countries where it is persistently dark during the winter season. 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 the relatively bright United States.Effect on motorcycle safety
A number of motorcycling advocacy groups are concerned over reduced motorcycle conspicuousness and increased vulnerability 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. 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, while other research has concluded there is a safety disadvantage to two × 520-candela DRLs on motorcycles in comparison to one × 270-candela dipped beam headlight. The latter result suggests that a daytime running lamp's luminous area may have an important influence on its effectiveness.Environmental impact
DRL power consumption varies widely depending on the implementation. Current production DRL systems consume from to over . 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. For that reason, low-power solutions are being encouraged and headlamp-based systems are not allowed after DRLs became mandatory in Europe at the beginning of 2011.
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 economy increases of up to may be found when comparing a 55-watt DRL system to a 200-watt DRL system. In 2006, the UK's Department of Transport also found significant reductions in emissions and fuel consumption when comparing a 42-watt DRL system to a 160-watt full headlight DRL systems. DRL fuel consumption can be reduced to insignificant levels by the use of 8-to-20-watt DRL systems based on LEDs or high-efficacy filament bulbs.
Worldwide
Europe
European Union
2008/89/EC required all passenger cars and small delivery vans first type approved on or after 7 February 2011 in the EU to come equipped with daytime running lights. European Union Directive 2008/89/EC ended validity on 31 October 2014, implicitly repealed by the replacement Regulation No 661/2009. which was replaced by Directive 2019/2144. The mandate was extended to trucks and buses in August 2012.Using headlamps or front turn signals or fog lamps as DRLs is not permitted; the EU Directive requires functionally specific daytime running lamps compliant with ECE Regulation 87 and mounted to the vehicle in accordance with ECE Regulation 48. DRLs compliant with R87 emit white light on an axis of between with an apparent surface of with an additional requirement of between in a defined field.
In the past, Germany, Spain, France and other European countries have encouraged or required daytime use of low beam headlamps on certain roads at certain times of year; Ireland encourages the use of low beam headlights during the winter, Italy and Hungary require daytime running lamps outside populated areas, and Bulgaria, Czech Republic, Estonia, Kosovo, Latvia, Lithuania, North Macedonia, Montenegro, Poland, Romania, Serbia, Slovakia and Slovenia require the use of full or reduced voltage low beam headlights at all times. Whether this requirement is met by the DRLs required on new cars since February 2011 is a matter of individual countries' laws.
Nordic countries
DRLs were first mandated in the Nordic 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. 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 on a 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 1985, 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 headlamp specifications in use in those countries, such an implementation would produce approximately axially.
United Kingdom
UK regulations briefly required vehicles first used on or after 1 April 1987 to be equipped with a dim-dip deviceor functionally dedicated daytime running lamps, except those vehicles type-approved to ECE Regulation 48 regarding installation of lighting equipment—this exception was made because ECE R48 did not require dim-dip or daytime running lights, and while countries signatory to the ECE Regulations are permitted to maintain their own national regulations as an option to the ECE regulations, they are not permitted to bar vehicles approved under the ECE regulations. The dim-dip system operated the low beam headlamps 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 straight ahead, and no more than in any direction. In practice, most vehicles were equipped with the dim-dip option rather than the running lamps.
The dim-dip lights were not intended for use as daytime running lights. Rather, they operated when the engine was running and the driver switched on the front position lamps. 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 low beam headlamps; 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.