Good headlights proven to reduce nighttime collisions
Nighttime crash rates per kilometer are nearly 20% lower for vehicles with headlights that score high in the IIHS rating, compared to those with low-rated headlights, the study found. . For vehicles with acceptable or marginal headlights, accident rates are 15% and 10% lower than low-rated vehicles.
“Driving at night is 3 times more risky than driving during the day,” says Matthew Brumbelow, senior research engineer at IIHS, who conducted the study. “This is the first study to document how headlights that provide better illumination can help.”
Reduction of nighttime collisions associated with good, acceptable and marginal headlights
Good score against bad score Acceptable against bad score Marginal against bad score All accidents Driving injury Pedestrian Animal-30% -25% -20% -15% -10% -50% 0%
Until 2016, when the IIHS launched its headlight assessment program, neither drivers nor researchers had a real way to compare the quality of illumination of different headlights on the roadway. The illumination provided by different lighthouses under real conditions varied widely, but the outdated federal standard effectively marked them all equal. Five years later, the IIHS evaluated approximately 1,000 different headlight systems, allowing Brumbelow to examine how headlights with good, fair, marginal, and bad ratings affect crash rates.
Brumbelow first identified 187 vehicle models from the 2015-2020 model years that were either available with a single IIHS rated headlight system or multiple systems that could be determined by the vehicle identification number (VIN). He then looked at police-reported crashes involving these vehicles in 11 states that keep particularly detailed records and isolated about 44,000 single-vehicle crashes that occurred in the dark. He adjusted the ratings to exclude any point deduction for excessive glare, as this is not a factor in single-vehicle crashes.
By controlling for differences in kilometers driven, driver-related risk factors and other variables such as different road conditions, well-rated headlights were associated with a 19% reduction in the rate of night-time accidents involving a single vehicle. , compared to the lowest rated. Acceptable and marginal headlights were associated with reductions of around 15 and 10 percent.
Brumbelow also found that the reductions were larger for specific types of accidents. Compared to worse ones, well-rated headlights reduced the rate of driver-injured crashes by 29%, and towing and pedestrian crash rates by about a quarter each.
“These actual results show that better scores in our headlight tests translate to safer night driving on the road, which of course is what really matters,” explains Brumbelow.
These cuts clearly show that federal lighthouse regulations, which haven’t changed much since 1968, are not tough enough. The federal standard specifies minimum and maximum brightness levels for headlights at different angles. However, it focuses on the headlight itself, regardless of how it is oriented when installed on a particular vehicle or how new technologies such as curve-adaptive headlights can alter that orientation when the vehicle is moving.
In contrast, the IIHS uses vehicles driven on a test track to conduct its evaluations. Ratings are based on how far the low beam and high beam headlamps illuminate the path up to 5 lux in curves and straights while traveling at 40-50 mph. Points are also deducted for glare which can temporarily blind oncoming drivers. (For reference, the end of twilight on a clear day is around 3 lux and the ambient light in the hallway of a typical office building is around 80).
Performance varies considerably. The low beam headlight illumination rated by the IIHS ranges from 125 feet to 460 feet. For the driver of a vehicle traveling at 80 km / h, this means a difference of 2 seconds against 6 seconds to recognize a potential danger and react by braking or steering.
By exposing these shortcomings and making high quality headlights a requirement for the THE BEST SAFETY CHOICE and THE BEST SAFETY CHOICE+ awards, the IIHS has encouraged manufacturers to offer better headlights on more vehicles.
Since the start of the program, the proportion of lighthouses with a good rating has increased from 4% to 29%. Regardless of their ratings, the average low beam illumination distance for all tested headlights increased from less than 180 feet to over 200 feet.
While Brumbelow didn’t factor in excessive glare in his analysis, measuring the glare of oncoming drivers is also an important part of the IIHS ratings. Here, too, the ratings led to improvements. In 2016, headlight systems assessed by the IIHS emitted an average of 15% more glare than the IIHS level considered acceptable. In 2020, the average glare was 10% below this threshold.
The difference is sometimes obvious. The headlights of a recently reviewed vehicle, the Mitsubishi Outlander 2022, went from poor to good only because of sighting adjustments made by the automaker to reduce glare in its bid for a THE BEST SAFETY CHOICE+ award, says David Aylor, director of active safety testing at IIHS.
“From some of the comments we’re getting on social media, it seems some people think we’re just pushing brighter headlights and ignoring the glare,” Aylor said. “The reality is quite the opposite.
Quality headlights have also become easier to find for customers as the Institute’s award criteria have evolved.
When the lighthouse evaluation program began, the ratings did not affect the THE BEST SAFETY CHOICE and THE BEST SAFETY CHOICE+ rewards. In 2017, the Institute began requiring that at least one good or acceptable headlight system be available for a vehicle to be eligible for THE BEST SAFETY CHOICE+. In 2019, this standard was adopted for the lower tier award and at least one high rated option was required for the “plus”. But for the most part, the best headlights have remained expensive additions that weren’t stocked by many dealerships, so the IIHS raised the bar again in 2020, requiring good or acceptable headlights across all grade levels. finish for THE BEST SAFETY CHOICE+ and the availability of at least one good or acceptable headlight system for THE BEST SAFETY CHOICE.
This recent move has accelerated the disappearance of inferior headlights from the market and has prompted manufacturers to simplify their offerings. Between 2019 and 2021, manufacturers reduced the number of headlight systems available for each vehicle model by 17%. Today, many car manufacturers equip their models with a single, good-quality headlight system as standard equipment. Examples include the 2021 Acura RDX, BMW 5 Series, Hyundai Palisade, and Subaru Outback.
Automakers made mid-year design changes to nearly 200 headlight systems in pursuit of one of two awards. Genesis has gone so far as to undertake a service campaign to make free retroactive adjustments for buyers of the 2021 Genesis G80 to ensure it qualifies for the highest accolade.
“Our awards have been a huge motivation for automakers to improve their headlights,” said Brumbelow. “Now, with our new study, we have confirmation that these improvements save lives.”