Hubbry Logo
Daytime running lampDaytime running lampMain
Open search
Daytime running lamp
Community hub
Daytime running lamp
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Daytime running lamp
Daytime running lamp
Daytime running lamp
View on Wikipedia
from Wikipedia

LED DRLs on an Audi R8
LED DRLs on a BMW 6 Series Gran Coupe

A daytime running lamp (DRL, also daytime running light) is an automotive lighting and bicycle lighting device on the front of a road going motor vehicle or bicycle.[1] 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.[2]

Implementations

[edit]
Full-voltage vs. parking light headlamp on European-market Volkswagen, 2007

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.[3]

Usage

[edit]

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.[4]

Safety performance

[edit]

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%.[5]

Effect of ambient light

[edit]

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.[3]

Effect on motorcycle safety

[edit]

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.[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 a safety disadvantage to two 90 mm (3+1⁄2 in) × 520-candela DRLs on motorcycles in comparison to one 190 mm (7+1⁄2 in) × 270-candela dipped (low) beam headlight. The latter result suggests that a daytime running lamp's luminous area may have an important influence on its effectiveness.[8]

Environmental impact

[edit]
LED daytime running lights on Audi A4

DRL power consumption varies widely depending on the implementation. Current production DRL systems consume from 5 W[9] (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.[10] For that reason, low-power solutions are being encouraged[11] 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 0.2 km/L (0.5 mpg‑US; 0.6 mpg‑imp) may be found when comparing a 55-watt DRL system to a 200-watt DRL system.[12] 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.[13] 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

[edit]

Europe

[edit]
Use of day driving lights for cars in Europe

European Union

[edit]
Hella 6-watt halogen-bulb DRLs for retrofit. Other retrofit DRLs use LEDs

European Union Directive 2008/89/EC required all passenger cars and small delivery vans [14] first type[clarification needed][15] approved on or after 7 February 2011 in the EU to come equipped with daytime running lights.[16][17][18] European Union Directive 2008/89/EC ended validity on 31 October 2014, implicitly repealed by the replacement Regulation (EC) No 661/2009.[19][20] which was replaced by Directive 2019/2144.[21] The mandate was extended to trucks and buses in August 2012.[22]

Using headlamps or front turn signals or fog lamps as DRLs is not permitted;[23] 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.[24] DRLs compliant with R87 emit white light on an axis of between 400 and 1,200 candela with an apparent surface of 25 to 200 cm2 (4 to 31 sq in) with an additional requirement of between 1 and 1,200 candela in a defined field.[25]

In the past,[when?] 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

[edit]
Hella DRL retrofit kit in selective yellow offered in Sweden in the 1970s. Package text reads "Install Hella perception lights so you are seen in traffic".
Early type of DRL as used by Volvo and Saab on Nordic markets in the 1970s and 1980s: Bright filaments were mounted in the front parking lamps as "perception light"

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 ("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 candela 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 450 candela axially.

United Kingdom

[edit]

UK regulations briefly required vehicles first used on or after 1 April 1987 to be equipped with a dim-dip device[26] or 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 (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.[26]

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 (parking) 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.[27]

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.[26] 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 (such as the Volkswagen Polo) well into the 1990s.

Canada

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

Canada Motor Vehicle Safety Standard 108 requires DRLs on all new vehicles made or imported after 1 January 1990. Canada's proposed DRL regulation was essentially similar to regulations in place in Scandinavia, with an axial luminous intensity limit of 1,500 candela, but automakers claimed it was too expensive to add a new front lighting device, and would increase warranty costs (due to increased bulb replacements) to run the low beams. After a regulatory battle, the standard was rewritten to permit the use of reduced-voltage high beam headlamps producing up to 7,000 candela axially, 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.

United States

[edit]

Shortly after Canada mandated DRLs, General Motors, interested in reducing the build variations of cars for the North American market, petitioned the US National Highway Traffic Safety Administration in 1990 to permit (but not require) US vehicles to be equipped with DRLs like those in Canada.[28] NHTSA objected on grounds of the potential for high-intensity DRLs to cause problems, such as glare and turn signal masking, and issued a proposed rule in 1991 that specified a maximum intensity of 2,600 candela.[28] Industry and safety watchdogs reacted to the proposed rule,[28] and eventually the glare objections were set aside and most of the same types of DRLs allowed in Canada were permitted but not required effective with the 1995 model year.[28] 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 US market beginning in 1995. In recent years,[when?] 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 and off switch. Starting in the 2006 model year, Honda began equipping their US 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 US. 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.[29] In 1997, in response to these complaints and after measuring actual DRL intensity well above the 7,000-candela limit on vehicles in use, DOT proposed changes to the DRL specification that would have capped axial intensity at 1,500 candela, a level equivalent to the European 1,200 candela and identical to the initially proposed Canadian limit.[28] During the open comment period, a volume of public comments were received by NHTSA in support of lowering the intensity or advocating the complete elimination of DRLs from US roads. Automaker sentiment generally followed prevailing experience with European automakers experienced at complying with European DRL requirements voicing no objection to the proposal, and North American automakers repeating the same objections they raised in response to Canada's initial 1,500-candela proposal.[29][30]

The NHTSA proposal for DRL intensity reduction was rescinded in 2004,[31] pending agency review and decision on a petition filed in 2001 by General Motors, seeking to have NHTSA mandate DRLs on all US vehicles.[32] The GM petition was denied by the NHTSA in 2009, on grounds of severe methodological and analytical flaws in the studies and data provided by GM as evidence for a safety benefit to DRLs.[32] In denying the petition, the NHTSA said:

[...] the agency remains neutral with respect to a policy regarding the inclusion of DRLs in vehicles [...] we do not find data that provides a definitive safety benefit that justifies Federal regulation [...] manufacturers should continue to make individual decisions regarding DRLs in their vehicles.[32]

Several states on the Eastern seaboard, the Southeast, Gulf Coast, and California have laws that require headlights to be switched on when windshield wipers are in use.[33] DRLs are not considered headlights in most vehicle codes and so DRLs may not meet the letter of these laws in use.

Australia

[edit]

DRLs are permitted but not required in Australia, though the Australasian College of Road Safety, an Australian automotive safety group, advocates making DRLs mandatory rather than optional.[34]

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Daytime running lamp

View on Grokipedia
from Grokipedia
A daytime running lamp (DRL), also known as a daytime running light, is an automotive front device that operates at reduced intensity during daylight hours to enhance conspicuity for other road users, thereby aiming to mitigate collision risks through improved detection. Originating in Scandinavian countries during the 1970s as a response to frequent foggy conditions and short daylight periods, DRLs gained regulatory traction, becoming mandatory in in 1989, across the since 2011 under UN ECE Regulation 87, and optional but widespread in the United States following NHTSA encouragement rather than federal mandate. Standards such as SAE J2087 specify photometric requirements, including minimum of around 400 and positioning to avoid , while empirical evaluations from bodies like NHTSA demonstrate DRL efficacy in reducing opposite-direction and pedestrian-involved crashes by 5-13%, with meta-analyses confirming broader daytime multi-vehicle accident reductions of 10-15% attributable to decreased "looked-but-failed-to-see" errors. Despite these benefits, implementation has sparked debate over potential drawbacks like marginal fuel consumption increases in older systems and inconsistent visibility gains in motorcycles, though LED adoption has largely alleviated efficiency concerns.

History

Origins in Nordic countries

The use of daytime running lamps, known in Swedish as varselljus ("perception light"), originated in Sweden during the late 1960s as a voluntary measure to enhance vehicle conspicuity in daylight conditions prevalent in Nordic regions, such as fog, overcast skies, and low ambient light that exacerbate human visual perception limitations. Early behavioral studies conducted in Sweden from the late 1960s examined factors like vehicle color and lighting effects on detection distances, revealing that unlit vehicles often blended into backgrounds, contributing to "look-but-fail-to-see" errors where drivers overlook oncoming traffic despite glancing in its direction due to insufficient contrast against daylight glare or camouflage. These pre-implementation analyses, including field tests showing reduced detection times with forward lighting, indicated potential reductions of 10-20% in multi-vehicle daytime collisions by improving mutual visibility without full headlamp intensity. Swedish automakers like pioneered integration of varselljus on production models, such as the 240 series, using low-intensity lamps in parking light housings to signal presence at reduced power compared to full beams. This voluntary adoption gained traction amid from accident data linking poor daytime conspicuity to a significant portion of collisions—estimated at up to 50% involving failure to detect other road users—prompting regulatory action. On October 1, 1977, Sweden mandated varselljus for all motor vehicles nationwide, year-round, marking the first widespread legal requirement driven by these studies rather than broader European harmonization. Neighboring Nordic countries followed with tailored mandates addressing similar environmental challenges. required daytime lights in 1972 initially for rural and snowy roads, expanding to urban areas by the 1990s to counter visibility issues in its variable winter daylight. implemented mandatory use in 1986, in 1988, and in 1990, each building on Swedish precedents and local data showing analogous benefits in reducing frontal and crashes during diffuse conditions common to the region. These adoptions prioritized low-power forward illumination to mitigate perceptual errors without excessive energy use, reflecting a causal focus on enhancing detection over aesthetic or uniformity concerns.

Expansion to Europe and North America

Canada became the first North American country to mandate daytime running lamps (DRLs) on new vehicles, requiring their installation on all passenger cars, multi-purpose vehicles, trucks, buses, and three-wheeled vehicles manufactured or imported after December 1, 1989, under Canada Motor Vehicle Safety Standard 108. This federal requirement aimed to enhance vehicle visibility during daylight hours, drawing from empirical evidence of crash reductions observed in where similar practices had been enforced since the 1970s. In , the expansion accelerated in the 2000s, culminating in European Union Directive 2008/89/EC, which mandated DRLs for all new passenger cars and small delivery vans type-approved on or after February 7, 2011. This directive amended earlier regulations to standardize DRL fitment across member states, extending the continent-wide based on safety analyses indicating reduced frontal and collisions. A pivotal 1997 meta-analysis by Rune Elvik, synthesizing 17 international studies, estimated an average 5.3% reduction in daytime multi-vehicle crashes attributable to DRL use, providing quantitative support for such mandates despite variations in study methodologies and latitudes. In the United States, regulatory resistance persisted, with the (NHTSA) declining to propose mandatory DRLs in the early 1990s after reviewing available data, citing insufficient conclusive evidence of net safety benefits in American driving conditions and potential glare hazards to opposing traffic. Instead, adoption remained voluntary; began equipping select 1995 models like the and with DRLs, expanding to all its vehicles by 1997, driven by internal assessments of Scandinavian data rather than federal compulsion. This approach reflected NHTSA's emphasis on cost-benefit analysis, where projected crash reductions did not outweigh concerns over increased fuel consumption and maintenance without tailored U.S. empirical validation. The global daytime running lamp (DRL) market, particularly for LED variants, reached an estimated $2.5-3.25 billion in 2025, with projections indicating a (CAGR) of approximately 7% through 2033, fueled by rising production and regulatory emphasis on visibility enhancements. This expansion reflects the near-universal integration of DRLs in new passenger vehicles worldwide, where LEDs now dominate implementations due to their compact design, rapid response times, and reduced power draw compared to prior systems. In the Asia-Pacific region, DRL adoption has accelerated, with mandatory requirements in South Korea since 2011 driving consistent market penetration, while Japan's 2020 mandate for automatic daytime lighting systems has standardized their use across new models. Australia maintains optional status under Australian Design Rules, yet DRLs have become de facto standard in OEM equipment since the mid-2010s, supported by aftermarket compliance trends and safety advocacy. LED efficiency has addressed early objections to DRLs' energy demands, with typical consumption under 2 watts per lamp versus 10-21 watts for equivalents, resulting in negligible fuel or battery impacts in modern vehicles and diminishing prior environmental concerns from the incandescent era. Post-2020 analyses confirm this minimal penalty, enabling broader acceptance amid electrification trends in .

Technical Specifications

Definition and regulatory standards

Daytime running lamps (DRLs) are automotive front-facing lights intended solely to improve conspicuity during daylight conditions, without serving as road illuminators. Under Economic Commission for Europe (UNECE) No. 48, which governs the installation of and light-signalling devices, a DRL is defined as "a lamp facing in a forward direction used to make the more easily visible when driving during daytime." These lamps must activate automatically upon operation in sufficient ambient light, deactivating when headlights or fog lamps engage, and are positioned to avoid masking turn signals or other mandatory lights. Unlike dipped-beam headlights, DRLs emit white light at lower intensities to prioritize detection over illumination, exploiting visual contrast mechanisms where human cone-dominated daytime vision benefits from outlined silhouettes against variably lit backgrounds. Photometric standards for DRLs, as detailed in UNECE Regulation No. 87 (incorporated via Regulation No. 48), require a of 400 to 1,200 along the , with an apparent surface area between 25 and 200 cm² to ensure balanced visibility without overwhelming glare. This range supports detection distances effective for typical highway approach speeds, where contrast enhancement counters limitations in peripheral acuity under high ambient (1,500–40,000 ). Lamps must produce steady, non-flashing light in a controlled beam pattern, with color coordinates limited to white (excluding ) to maintain uniformity across jurisdictions adopting ECE standards. In the United States, Federal Safety Standard (FMVSS) No. 108 permits voluntary DRL implementation but mandates they function as steady-burning auxiliaries that illuminate only when headlamps are off, without obscuring stop lamps, turn signals, or other required devices during activation. Unlike ECE requirements, FMVSS 108 does not prescribe dedicated DRL intensity minima or maxima for separate fixtures, allowing adaptations like voltage-reduced headlamps (up to 7,000 permissible in some configurations) provided they meet overall photometric tables and do not exceed thresholds. European implementations emphasize dedicated low-power units, often LED-based for efficiencies around 5–10 watts per lamp, contrasting with U.S. flexibility that accommodates higher-output repurposed elements while prioritizing non-interference with signaling integrity.

Types of DRL implementations

Dedicated daytime running lamps (DRLs) commonly feature separate (LED) arrays or strips positioned in the housings or front fascia, a design that gained prominence in the mid-2000s with manufacturers like pioneering production models such as the 2004 A8 equipped with horizontal LED bars. These dedicated systems prioritize efficiency, drawing approximately 5 watts per side while emitting focused white light for enhanced frontal visibility without significant electrical load. Empirical assessments confirm their low consumption relative to alternatives, with LED DRLs averaging 5-10 watts total versus higher-draw legacy bulbs, enabling longevity exceeding 50,000 hours under automotive conditions. Headlamp-integrated DRLs repurpose low-beam filaments or modules, a method originating in Nordic countries where Sweden mandated low-beam usage in 1977, often at near-full intensity to compensate for low ambient light in winter months. These setups historically consume 40-60 watts per due to or early HID elements, with total system draw reaching 100 watts or more for paired lamps, contributing to measurable fuel penalties in fleet analyses from the era. Dimming via or reduced voltage mitigates this somewhat in later adaptations, but power demands remain elevated compared to dedicated LEDs, reflecting trade-offs in existing . Signal repurposed DRLs incorporate front turn indicators, position lamps, or lamps to fulfill daytime requirements, particularly in regions permitting multifunctional to minimize added hardware. Such integrations, evaluated in U.S. regulatory contexts, necessitate automatic deactivation of the DRL function upon turn signal activation to prevent masking, as continuous proximity illumination can reduce the perceptual contrast of flashing indicators by up to 50% in detection tests. NHTSA's 1991 proposed rulemaking highlighted this risk, citing empirical glare and conspicuity data from prototype evaluations where non-deactivating DRLs near turn signals impaired oncoming driver recognition. variants in these roles draw 10-21 watts per lamp, balancing visibility against the need for sequential dimming circuits.

Integration with vehicle systems

Daytime running lamps (DRLs) integrate with the vehicle's (ECU) and Controller Area Network ( to enable automatic activation upon engine or ignition start, coordinating with other lighting systems for synchronized operation. Ambient light sensors, typically photocells mounted near the , detect conditions above approximately 1,000 to confirm daytime illumination, triggering DRLs while deactivating them in low-light scenarios to transition to full headlights. This CAN-bus linkage ensures low-latency signaling, preventing conflicts with systems like parking aids or instrument clusters, and supports (PWM) for efficient LED control without flickering. Advanced implementations incorporate adaptive features tied to ADAS, where DRL intensity adjusts dynamically based on environmental inputs, such as dimming upon tunnel entry to mitigate glare while maintaining visibility. In post-2020 electric vehicles, integration with battery management systems optimizes DRL operation to limit drain, using low-power modes or selective activation linked to regenerative braking status. These features reduce reliance on manual switches, minimizing human error in light deployment. However, the added complexity introduces failure risks, including sensor malfunctions from , misalignment, or electronic drift, which can cause unintended DRL deactivation during daylight or erroneous activation at night. Automotive surveys highlight that such vulnerabilities in sensors, including detectors, contribute to intermittent system unreliability, necessitating regular diagnostics via onboard self-tests.

Safety Efficacy

Empirical evidence of crash reduction

A conducted by Elvik in 1997, encompassing 17 studies on the safety effects of daytime running lights (DRL) on passenger cars, estimated an overall crash reduction of approximately 5%, with a more pronounced 10-15% decrease specifically in multi-vehicle daytime accidents involving DRL-equipped vehicles. This employed log-odds methods to aggregate data from observational and experimental evaluations, primarily focusing on frontal and side-impact collisions where plays a critical role. The SWOV Institute for Road Safety Research's 1997 review corroborated these findings, noting that DRL addresses failures, which contribute to roughly 50% of daytime multi-vehicle accidents through mechanisms such as inadequate detection of approaching vehicles. Such failures often stem from low lateral contrast between vehicles and the background, a factor DRL mitigates by enhancing the apparent distance and motion cues of oncoming or crossing traffic, thereby aligning with accident causation models emphasizing errors. Post-1990 implementation data from , following the federal mandate for DRL on new vehicles, indicated a 5.3% reduction in combined opposing and collision rates, with separate analyses reporting up to 8.3% fewer daytime multi-vehicle crashes attributable to DRL use. These naturalistic evaluations drew from claims and police-reported incidents, isolating DRL effects via before-after comparisons of equipped versus non-equipped fleets. European Union assessments post-2011 DRL mandation for new cars similarly documented multi-vehicle daytime crash reductions in the 5-10% range, consistent with pre-mandate projections and Nordic precedents.

Criticisms including glare and masking

High-intensity daytime running lamps (DRLs) have drawn criticism for generating that impairs visibility for oncoming drivers, particularly on curved roads or in low-ambient-light conditions where the relative brightness exacerbates discomfort. The Dutch Institute for Road Safety Research (SWOV) has documented that DRLs produce glare when their luminous intensity exceeds levels appropriate for prevailing illumination, potentially distracting or temporarily blinding drivers. In the United States, the (NHTSA) received thousands of public complaints about DRL-induced glare shortly after permitting their voluntary use on passenger vehicles in the early , highlighting concerns over unintended visual interference during daylight hours. Another key drawback is the masking of turn signals by DRLs, which diminishes their detectability and compromises signaling effectiveness. Research from the Transportation Research Institute (UMTRI) demonstrates that front turn signal conspicuity decreases when adjacent lights, such as headlamps operating as DRLs, create simultaneous illumination, with masking effects observed across various front-end configurations. SWOV similarly warns that sufficiently bright DRLs can obscure turn signals on the same , reducing their perceptual salience for other users. From a perceptual standpoint, DRLs contribute to visual uniformity that erodes contrast-based cues essential for discerning shape, distance, and motion, as contrast gradients underpin human visual detection in daylight per established vision principles. This effect is pronounced in high-ambient-light scenarios like sunny days, where DRLs provide negligible conspicuity gains due to diminished differences, rendering them ineffective for crash avoidance in bright conditions.

Specific impacts on motorcycles and ambient light

Studies have raised concerns that widespread adoption of daytime running lights (DRLs) on automobiles could reduce conspicuity by creating a lit environment in which unlit or differently lit motorcycles become less salient to drivers, potentially elevating car-motorcycle collision risks through perceptual masking. A NHTSA evaluation of driver gap acceptance in regions with varying DRL penetration rates (30-50% in the U.S. versus 90% in ) found no statistically significant differences in detection or response to oncoming motorcycles attributable to fleet DRL use, with accepted gaps for motorcycles comparable to those for vehicles in high-DRL areas (e.g., approximately 178 feet versus 179 feet). However, the same analysis noted inconclusive on-road data comparability and recommended further investigation into side-conspicuity effects, where no detection distance reductions were observed but short gaps critical for safety remained rare (<2.3% of events). Evaluations of DRL policies provide mixed evidence on motorcycle-specific benefits. In Norway's implementation, motorcyclist crash rates showed a non-significant 4% increase post-mandate, contrasting with overall multi-vehicle daytime reductions and suggesting possible null or adverse subgroup effects without compensatory conspicuity gains for motorcycles. No broad empirical support exists for significant crash reductions among motorcyclists from automobile DRLs, as perceptual studies indicate hampered relative detection of two-wheeled vehicles amid lit car fleets. DRL efficacy diminishes in high ambient light conditions, such as bright sunlight above 10,000 , where elevated background limits contrast enhancement from low-intensity lamps (e.g., 400 cd showing minimal detection improvements beyond 1,000 ). SWOV analyses confirm greater relative benefits in lower illumination, with voluntary DRL usage dropping to 12-20% in bright summer conditions versus 40-80% in , rainy, or weather, correlating with intrinsic casualty reductions of 30-77% in Nordic winter/low-light scenarios due to improved target contrast. In or , DRLs extend detection distances (e.g., +24 meters at 70,000 with 2,000 cd intensities, scaling higher in reduced visibility) without at below 100-200 cd/m², though effectiveness varies by latitude and seasonal sunlight angles, yielding curvilinear gains favoring northern regions. A 2022 naturalistic cycling study observed elevated physiological stress (e.g., heart rate variability) in cyclists during vehicle passing events involving DRL-equipped cars, attributing discomfort to glare or proximity perception, though no causal link to crashes was established; similar dynamics may heighten perceived risks for motorcyclists in mixed traffic without establishing broad accident causality.

Regulatory Frameworks

Europe

Nordic countries led the adoption of daytime running lamps (DRLs) due to frequent low-light conditions during winter months. Sweden implemented the world's first mandatory DRL requirement on October 1, 1977, applying to all motor vehicles year-round. Norway enacted a similar mandate in 1986, followed by Iceland in 1988 and Denmark in 1990. These early regulations focused on enhancing vehicle visibility in regions with limited daylight, predating broader European harmonization by decades. The standardized DRL requirements via Directive 2008/89/EC, which mandates automatic DRLs on all new passenger cars (category M) and light commercial vehicles up to 3.5 tonnes (category ) type-approved from February 7, 2011 onward. This applied EU-wide to improve daytime conspicuity and reduce collisions, building on Nordic precedents where DRLs demonstrated safety benefits. The directive specifies DRL activation with the engine and luminance between 400 and 1,200 per lamp. Post-Brexit, the maintained the DRL obligation for new passenger cars and car-derived vans through retained EU law and alignment with UNECE Regulation 48, ensuring continuity in type approval standards. Enforcement across occurs via national regimes, such as annual MOT tests in the UK or equivalents in , where non-compliant DRLs can result in failed certification and fines varying by country—typically €50-€200 for minor lighting violations. By the mid-2010s, DRL equipping reached near-universality among new vehicles, reflecting stringent manufacturer compliance to secure market access.

North America

In Canada, daytime running lamps (DRLs) have been federally mandated since December 1, 1989, under Canada Motor Vehicle Safety Standard 108, requiring all new passenger cars, multi-purpose passenger vehicles, trucks, buses, and three-wheeled vehicles manufactured or imported for sale in the country to be equipped with at least two DRLs. This regulation ensures 100% compliance among new vehicles sold in , with DRLs required to activate automatically under normal daytime conditions without manual intervention. In contrast, the has no federal requirement for DRLs, with the (NHTSA) permitting them as optional equipment under Federal Motor Vehicle Safety Standard (FMVSS) No. 108 since the early 1990s, but rejecting mandates due to insufficient evidence of net safety benefits outweighing potential drawbacks like . NHTSA denied a 2001 petition from to require DRLs on all new vehicles, citing methodological flaws in supporting studies and concerns over increased fuel consumption and signal masking. Despite the absence of a mandate, voluntary adoption has grown substantially, with most new passenger cars, SUVs, and light trucks equipped with DRLs by the mid-2010s onward, achieving exceeding 60% across the light vehicle fleet by 2025 through manufacturer standards, particularly among European imports and domestic brands like GM and Ford. State-level regulations in the vary but do not impose DRL requirements; instead, some enforce "wipers-on, lights-on" rules mandating headlamps (which may incorporate DRL functions) during , such as in , where Vehicle Code Section 24400 requires lights when visibility is reduced or wipers are used, but explicitly does not mandate standalone DRLs. permits aftermarket DRL installations provided they comply with FMVSS 108 photometric and mounting standards, without prohibiting modifications on vehicles not originally equipped. Other states like , , and similarly tie daytime lighting to wiper use rather than requiring dedicated DRLs.

Other regions including Australia and Asia

In Australia, daytime running lamps (DRLs) have been optional since the introduction of Australian Design Rule (ADR) 76 in the early 2000s, building on voluntary adoption trends from the 1990s driven by manufacturer safety enhancements rather than legal mandates. Compliance is required for fitted vehicles, specifying photometric intensity between 400 and 800 candela per lamp, white light projection, and automatic deactivation when headlights activate to prevent overuse. By 2023, DRLs had become standard equipment on nearly all new passenger vehicles sold domestically, reflecting global harmonization with UN ECE standards and empirical data linking them to reduced frontal collisions, though without nationwide enforcement. Across Asia, DRL regulations vary by country, with mandatory requirements in select markets accelerating uptake amid rising vehicle production. mandates DRL installation on new vehicles to mitigate daytime accidents, with revisions to vehicle lighting standards in 2023 incorporating light source specifications like LEDs for compliance. In , while (AIS-012 Part 10, revised 2018) outline performance criteria such as minimum and vibration resistance for DRLs, fitment remains voluntary for four-wheeled vehicles, contrasting with compulsory automatic headlight-on (AHO) systems for two-wheelers since 2017. Japan enforces automatic headlight activation in low light via UN Regulation 48 since April 2020 for new passenger cars, but dedicated DRLs are optional, with manufacturers often integrating them for export compliance or aesthetic LED strips. In , DRLs lack explicit mandates under GB 5920-2019 lighting standards, yet adoption surges voluntarily—often via non-disableable LEDs—due to safety campaigns and alignment with international norms, with updated rules from July 2025 enabling advanced features like adaptive cornering lamps. Overall, LED-based DRL prevalence in Asian new vehicles exceeds 70% as of 2024, propelled by cost efficiencies and partial regulatory alignment in emerging markets.

Environmental Considerations

Fuel consumption and emissions effects

Early implementations of daytime running lamps (DRLs), which often relied on continuously operating low-beam headlights at reduced intensity, increased vehicle fuel consumption by approximately 0.9% due to the additional electrical load on the and . This effect stemmed from the constant power draw—typically 40-55 watts per headlight pair—requiring the to generate extra output to recharge the battery and supply the lights, thereby raising overall demand across driving cycles. Dedicated DRL configurations, using separate lower-wattage bulbs, yielded a smaller penalty of about 0.5%, while full dipped-beam usage as DRLs escalated it to 1.8-1.9%. In the , SWOV estimated that widespread DRL adoption equivalent to low-beam operation would add 2,420 million liters of consumption annually to the passenger car fleet, based on 1997 vehicle kilometers traveled and efficiency data. This volume corresponded to elevated CO2 emissions, with each liter of producing roughly 2.3 kilograms of CO2, resulting in millions of tons fleet-wide; more granular per-vehicle figures indicate an increment of 7 grams CO2 per kilometer from DRL operation. For motorcycles, the relative energy penalty remained negligible—far below 1% of total use—owing to smaller lamp wattage and higher power-to-weight ratios in two-wheeled vehicles.

Reductions via LED and efficient technologies

The transition to (LED) technology for daytime running lamps (DRLs) has markedly decreased their energy consumption relative to halogen predecessors. LED DRLs typically require 5-10 watts per unit, compared to 20-55 watts for systems operating in reduced-intensity modes, achieving up to 80-90% lower power usage. This efficiency confines the fuel economy penalty to approximately 0.1-0.5% in LED-equipped vehicles, versus up to 2% observed in older configurations where DRLs relied on partial headlight filaments. Post-2010 empirical assessments confirm that LED adoption yields net emissions reductions for vehicle lighting, as lifetime savings surpass production impacts and offset operational drawbacks of earlier DRL mandates. Life-cycle analyses indicate global light-provision could decline by over sevenfold through efficient sources like LEDs, with automotive applications mirroring this trend via prolonged bulb life exceeding 25,000 hours and minimal heat generation. Advanced features such as adaptive dimming, which modulate DRL intensity based on ambient conditions via digital controls, provide additional savings of 10-20% in average power draw. In electric vehicles, where DRLs draw from battery reserves, LED efficiencies combined with projected 2030 battery advancements render range impacts near-zero, often below 0.1% of total capacity under typical usage. These developments ensure DRL environmental costs are minimized without compromising visibility benefits.

Controversies

Debates on net safety benefits

Studies evaluating the net benefits of daytime running lamps (DRLs) have yielded conflicting results, with meta-analyses generally supporting modest reductions in certain crash types but highlighting limitations in isolating causal effects and potential offsetting risks. A 1996 meta- of 17 studies found that DRLs on cars reduced multi-party daytime accidents by approximately 10-15%, primarily through improved vehicle detectability in multi-vehicle collisions such as head-on or front-to-side impacts. Subsequent syntheses, including a 2023 evaluation of fleet data, estimated an 8.8% reduction in non-nighttime multi-vehicle crashes overall, with stronger effects (up to 20%) during dawn, , or lower ambient light conditions where challenges are more pronounced. These benefits are attributed to enhanced conspicuity, as perceptual studies indicate DRLs aid timely detection of vehicles in , though effects appear attenuated in bright when baseline is high and most occurs. Critics argue that apparent benefits may not represent net gains due to unaccounted confounders and countervailing effects, such as self-selection bias where DRL-equipped vehicles (often newer models) coincide with concurrent improvements like advanced braking systems or seatbelt usage, inflating attributed . U.S.-based observational studies have reported smaller or insignificant effects; for instance, a NHTSA found no statistically significant reductions in key crash types except a 5.7% drop for light trucks in multi-vehicle incidents, while a Minnesota crash rate comparison from 1995-2002 showed no difference in opposite-direction collisions. Additionally, DRLs on cars have been linked to reduced conspicuity, with experimental evidence demonstrating hampered detection of motorcycles at distance when cars display DRLs versus no lights, potentially via masking or glare that diminishes the relative salience of motorcycle headlamps. The debate underscores challenges in from observational data, as randomized controlled trials are infeasible, leaving meta-analyses vulnerable to favoring positive results and geographic variations (e.g., stronger Scandinavian effects versus U.S. data). Recent fleet-level assessments remain mixed, with some affirming overall daytime crash reductions but questioning universality without controls for ambient conditions or secondary risks like glare-induced hazards to vulnerable users such as motorcyclists. Net positivity thus hinges on whether primary gains outweigh these offsets, with empirical synthesis privileging targeted multi-vehicle reductions in suboptimal light over anecdotal or uncontrolled claims of broad efficacy.

Cost-benefit analyses and economic critiques

In the , cost-benefit analyses conducted prior to the 2011 mandate for DRLs on new vehicles estimated benefit-cost ratios ranging from 2 to 5, with monetized safety benefits from reduced daytime multi-vehicle crashes exceeding implementation costs, including additional consumption for halogen-based systems. These benefits were projected to stem primarily from fewer frontal and intersection accidents, potentially averting thousands of fatalities annually across the EU fleet, though one analysis questioned the differential impact on severe versus minor injuries as lacking robust empirical support. Pre-LED costs were estimated at approximately 0.9 liters per 1,000 km for standard DRL operation in small vehicles, translating to economy-wide expenses in the hundreds of millions of euros annually when scaled to fleet usage, though exact aggregates varied by vehicle type and driving patterns. Critiques of EU mandates highlight overregulation, arguing that hardware requirements impose unnecessary upfront manufacturing and retrofit expenses—potentially €50-100 per vehicle—while alternatives like public awareness campaigns on visibility could achieve similar outcomes at lower marginal cost without altering vehicle design. In the United States, the National Highway Traffic Safety Administration (NHTSA) declined to mandate DRLs after multiple studies, concluding in 2009 that costs such as incremental fuel use, glare-related adaptation issues for other drivers, and production modifications outweighed unproven net safety gains, with no statistically significant overall crash reductions identified in comprehensive reviews. NHTSA's 1981 assessment similarly deemed results inconclusive, prioritizing voluntary adoption over federal compulsion due to the modest estimated fuel penalty—a fraction of a mile per gallon for halogen DRLs—and absence of compelling causal evidence linking DRLs to broad economic savings in crash-related damages. The widespread shift to LED technology by 2025 has reduced DRL energy draw by up to 90% compared to halogen predecessors (e.g., from 160 watts to 16 watts per pair), minimizing fuel costs to negligible levels—often under 0.1% of total vehicle consumption—and potentially retroactively bolstering cost-benefit ratios in jurisdictions with mandates. Nonetheless, economic critiques persist that early mandates were premature, forgoing first-principles evaluation of behavioral interventions or phased tech adoption, and that regulatory inertia overlooks diminishing marginal returns as baseline vehicle conspicuity improves through other advancements like brighter taillights. Proponents of scrutiny emphasize that without rigorous, jurisdiction-specific monetization of like increased glare complaints or enforcement overhead, DRL policies risk net societal losses despite apparent safety intents.

References

  1. https://www.geotab.com/glossary/daytime-running-lights/
  2. https://www.moreycorp.com/drl-a-guide-to-daytime-running-lamps/
  3. https://undergroundlighting.com/blogs/headlight/daytime-running-lights-complete-guide
  4. https://www.dun-bri.com/Regulations-Standards/UNECE-Regulations/Guide-To-ECE-R87-Daytime-Running-Lamps
  5. https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/809760
  6. https://pubmed.ncbi.nlm.nih.gov/9006637/
  7. https://www-esv.nhtsa.dot.gov/Proceedings/19/05-0178-W.pdf
  8. https://trid.trb.org/View/173204
  9. https://www.sciencedirect.com/science/article/pii/0001457580900536
  10. https://swov.nl/system/files/publication-downloads/r-97-36.pdf
  11. https://www.sciencedirect.com/science/article/abs/pii/000145759500015R
  12. https://headlights.com/how-daytime-running-lights-became-mandatory-in-most-countries/
  13. https://www.lightsout.org/story.html
  14. https://www.drivesmartbc.ca/safety-equipment/viewpoint-daytime-running-lights
  15. https://www.gov.uk/government/publications/daytime-running-lights/daytime-running-lights
  16. https://www.sema.org/news-media/enews/2009/27/nhtsa-rejects-mandatory-daytime-running-lamps
  17. https://www.govinfo.gov/content/pkg/FR-1995-07-07/html/95-16687.htm
  18. https://www.latimes.com/archives/la-xpm-1994-05-09-fi-55590-story.html
  19. https://www.archivemarketresearch.com/reports/led-daytime-running-light-604243
  20. https://www.verifiedmarketreports.com/product/led-daytime-running-light-market/
  21. https://www.marketreportanalytics.com/reports/automotive-daytime-running-lamps-149541
  22. https://dataintelo.com/report/daytime-running-lights-market
  23. https://www.linkedin.com/pulse/automotive-daytime-running-lights-industry-market-tdaff/
  24. https://www.drivingvisionnews.com/news/2020/04/07/automatic-lights-now-required-in-japan%25E2%2580%25A8/
  25. https://www.ozled.com.au/blog/are-your-daytime-running-lights-drl-adr-compliant/
  26. https://www.theguardian.com/australia-news/2023/jun/02/what-are-daytime-running-lights-on-cars-and-would-they-make-victorian-roads-safer
  27. https://www.jwspeaker.com/blog/education-center/why-automakers-are-integrating-led-lighting-into-designs/
  28. https://carlightvision.com/blog/led-car-headlights-market-growth-trends/
  29. https://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2015/R048r12e.pdf
  30. https://deepblue.lib.umich.edu/bitstream/handle/2027.42/55184/UMTRI-2003-11.pdf
  31. https://unece.org/DAM/trans/doc/2010/wp29gre/ECE-TRANS-WP29-GRE-64-41e.pdf
  32. https://www.federalregister.gov/documents/2009/06/29/E9-15314/federal-motor-vehicle-safety-standard-no-108-lamp-reflective-devices-and-associated-equipment
  33. https://researchbriefings.files.parliament.uk/documents/SN01361/SN01361.pdf
  34. https://www.audi-technology-portal.de/en/electrics-electronics/lighting-technology/led-daytime-running-lights
  35. https://www.datamintelligence.com/research-report/automotive-daytime-running-lights-market
  36. https://www.newscientist.com/article/mg18725111-900-turned-off-by-daytime-driving-lights/
  37. https://www.diodes.com/design/support/technical-articles/led-control-maximizes-benefits-of-daylight-running-lamps
  38. https://carlightvision.com/blog/daytime-running-lights-vs-headlights/
  39. https://archives.federalregister.gov/issue_slice/1991/8/12/38099-38108.pdf
  40. https://www.motor.com/magazine-summary/trouble-shooter-november2015/
  41. https://www.vdrsyd.com/mp/drl.html
  42. https://nelsonfordsales.com/blog/what-if-i-leave-the-light-switch-in-auto-mode-on-a-f-150/
  43. https://www.linkedin.com/pulse/how-vehicle-daytime-running-lamps-works-one-simple-qvssc/
  44. https://blog.theretrofitsource.com/what-is-a-can-bus-system/
  45. https://www.researchgate.net/publication/395803996_An_Adaptive_Headlight_Dimming_Systems_for_Enhanced_Night_Driving_Safety_with_Machine_Learning_on_ARM_Boards
  46. https://ultrabrightlightz.com/blogs/ubl-insider/what-are-daytime-running-lights
  47. https://www.hella.com/techworld/us/technical/automotive-lighting/electronic-control-units-in-contemporary-vehicles-with-led-headlamps/
  48. https://pmc.ncbi.nlm.nih.gov/articles/PMC11360603/
  49. https://www.tandfonline.com/doi/full/10.1080/23311916.2024.2353498
  50. https://www.sciencedirect.com/science/article/abs/pii/S0001457596000413
  51. https://www.sciencedirect.com/science/article/pii/S002243759700011X
  52. https://trid.trb.org/View/460056
  53. https://www.researchgate.net/publication/242659732_The_Safety_Effects_of_Daytime_Running_Lights
  54. https://deepblue.lib.umich.edu/bitstream/handle/2027.42/49440/UMTRI-2000-44.pdf?sequence=1&isAllowed=y
  55. https://www.sciencedirect.com/science/article/abs/pii/S0001457511002508
  56. https://www.nhtsa.gov/sites/nhtsa.gov/files/811504.pdf
  57. https://www.ibiblio.org/rdu/DRLs/studies.htm
  58. https://pubmed.ncbi.nlm.nih.gov/8579694/
  59. https://europa.eu/rapid/press-release_IP-11-133_en.htm
  60. https://www.powerbulbs.com/eu/blog/2019/12/are-daytime-running-lights-compulsory
  61. https://www.quora.com/In-the-UK-is-there-still-a-requirement-for-new-cars-sold-to-be-fitted-with-daylight-running-lights-after-Brexit
  62. https://www.carri.com.cn/news/understanding-daytime-running-lights.html
  63. https://www.dklaw.com/the-fine-print/what-are-californias-headlight-laws/
  64. https://www.law.cornell.edu/regulations/california/13-CCR-694
  65. https://gomotive.com/blog/daytime-running-lights-drl/
  66. https://www.infrastructure.gov.au/infrastructure-transport-vehicles/vehicles/vehicle-design-regulation/australian-design-rules/third-edition
  67. https://classic.austlii.edu.au/au/legis/nt/consol_reg/avsr324/s85.html
  68. https://igarr.com/2023/12/22/korea-revision-of-the-main-technical-regulation-for-vehicles/
  69. https://morth.nic.in/sites/default/files/ASI/10252018113443AMAIS-012_Part10_Rev.2_D2.pdf
  70. https://etsc.eu/india-to-require-daytime-lights-for-motorcycles/
  71. https://www.china-certification.com/en/updates-to-two-automotive-lighting-gb-standards/
  72. https://skeptics.stackexchange.com/questions/20400/is-a-cars-fuel-consumption-increased-when-the-headlights-are-on
  73. https://motorcycleminds.org/virtuallibrary/daytimerunninglights/daytimerunninglampsfinalreport.pdf
  74. https://www.sciencedirect.com/science/article/pii/S0360128516300442
  75. https://rimthin.com/blogs/rimthin-blog/led-vs-halogen-headlights-comparison-guide
  76. https://www.energy.gov/energysaver/lighting-choices-save-you-money
  77. https://forums.tdiclub.com/index.php?threads/led-daytime-running-lights-worthwhile-project.90586/
  78. https://www.researchgate.net/publication/282940921_Potential_Long-Term_Global_Environmental_Implications_of_Efficient_Light-Source_Technologies
  79. https://www.researchgate.net/publication/331665656_Environmental_and_Energy_Improvements_of_LED_Lamps_over_Time_A_Comparative_Life_Cycle_Assessment
  80. https://www.avnet.com/apac/resources/article/auto-leds-deliver-greater-design-flexibility/
  81. https://www.iea.org/reports/global-ev-outlook-2025/outlook-for-energy-demand
  82. https://www.futuremarketinsights.com/reports/ev-lighting-market
  83. https://www.sciencedirect.com/science/article/abs/pii/S0022437523000099
  84. https://www.jalopnik.com/daytime-running-lights-reduce-risk-of-car-crash-1850344868/
  85. https://deepblue.lib.umich.edu/bitstream/2027.42/919/2/81361.0001.001.pdf
  86. https://pmc.ncbi.nlm.nih.gov/articles/PMC2850978/
  87. https://www.nhtsa.gov/sites/nhtsa.gov/files/811507.pdf
  88. https://road-safety.transport.ec.europa.eu/european-road-safety-observatory/statistics-and-analysis-archive/cost-benefit-analysis-measures/promising-road-safety-measures-based-cost-benefit-analyses_en
  89. https://www.trl.co.uk/publications/ppr170
  90. https://www.nhtsa.gov/interpretations/1985-0415
  91. https://ledoutfitters.com/blog/how-much-extra-gasoline-would-americans-use-if-daytime-running-lights-were-mandatory/page-38/
  92. https://www.softlights.org/wp-content/uploads/2022/02/NHTSA-ADB-Final-Rule-Response.pdf
Add your contribution
Related Hubs
User Avatar
No comments yet.