Glaring, bluish-white LED car headlights that cause unpleasant glare: anyone who takes part in road traffic in the evening and at night can increasingly tell you a thing or two about it. the dangerous glare comes directly from the front (oncoming traffic) or indirectly through side and rearview mirrors.
The fact that there are more and more of them can be seen particularly clearly when driving on the freeway. Because that’s where the glaring, bluish-white headlights of oncoming cars stand out most clearly between the otherwise rather yellowish-white headlights. SUVs and off-road vehicles are particularly dazzling because the LED headlights on these vehicles are mounted higher due to their design. And there are more and more of these vehicles on germany’s roads. Around one-third of new registrations in 2019 were off-road vehicles and SUVs.
More and more people are rightly asking why these dazzling headlights are allowed at all.
"flying blind" for seconds
The fact is that LED headlights consume very little energy and at the same time offer an enormous amount of brightness. And it is also a fact that whitish light with high blue components in the spectrum (so-called cold white or daylight white light) leads to better color recognition and thus to better visibility of contrasts at night. Reason enough for the car industry to install mainly such headlights. But what serves the driver of such a vehicle is a major problem for all other oncoming road users. because we humans perceive bluish light (with the same amount of light) to be significantly brighter and thus also significantly more dazzling than yellowish light.
At night, the pupil of the eye is always wider open than during the day. The darker the surroundings, the wider they open up. Because of the darkness, the light-sensitive rods on the retina of the eye are now predominantly activated. These are mainly located in the edge areas of the retina. If the eye now encounters the glare of an oncoming vehicle, not only is the pupil opening automatically reduced to protect the eye, but we also reflexively look directly into the glaring, blinding light source. With this reflex, the eye protects itself. because by looking directly into it, most of the light hits the retina in the center. There are the light-insensitive cones that are responsible for daytime vision. In the meantime, however, our gaze is no longer fixed on the road ahead of us. A short "blind flight. If the glare is particularly intense, we even close our eyes completely. The more intense the glare, the longer it takes the eye to restore its original dark vision. This can take many seconds, even minutes. If you have spent a long time in a very bright interior room and then step outside under the starry sky, it can take more than half an hour before you can see the stars in their full glory, i.e. your eyes are fully dark-adapted again. In general, the brighter and bluer the light falling into the eye, the longer it takes the eye to "recover. And the older you are, the longer this process takes.
There are two main types of LED car headlights: free-form reflector systems and the much more common lens projection systems. Unlike free-form reflector systems (in which the reflector surfaces from which all the light is emitted to the front are relatively large), the light-emitting surface of lens projection systems is much smaller. This leads to enormously high luminance levels (d.H. A lot of brightness in relation to the emitting surface). And this in turn leads to enormous dazzling of other road users. High luminance and a lot of blue in the light at the same time is an extremely bad mixture for our eyes. If you are exposed to such intense bluish light for too long, you may well suffer permanent eye damage. Toxic substances are formed for the retina, which then attack it and cause it to die. With LED car headlights, however, it is at least enough to cause a psychological glare, and in some cases (according to ophthalmologists) even a physiological glare. The older you get, the more cloudy your eyes become. And so glare is even more intense in older people, because the light from the bright bluish car headlights is scattered relatively strongly as it passes through the clouded lens of the eye. In the case of oncoming vehicles with bright, bluish-white LED headlights, this means that we repeatedly drive almost blind for fractions of a second or even several seconds. Two seconds of blind flight at speed 100 means a distance covered of over 50 meters.
But risky glare can also occur for following road users. Namely, when the car ahead has LED brake lights. Red is significantly less dazzling (with the same amount of light) than bluish-white light, but it can still be unpleasantly dazzling.
the situation is becoming even more acute the more we see such enormously bright bluish light sources in road traffic and the even smaller the manufacturers realize the radiating surfaces in car headlights. Thanks to low-cost LED technology, which offers high luminance levels on very small beam areas (and also allows almost any conceivable construction design), this is exactly what is happening. Strong glare. It makes no difference to the eye whether the glaring white LED light is emitted by vehicle headlights or by modern and usually far too bright LED street lamps or even LED advertising signs that fly past and over us while we are driving.
If lens projection systems are to be used, then please only for high beams
It is to be hoped that the vehicle manufacturers, who mainly rely on the lens projection system, will make the best use of this for the high beam. Because that’s what you usually switch off when a road user is coming towards you. But many manufacturers also use this LED light system for dipped headlights. The ADAC [1], a German automobile association, is now calling for lens projection systems to be used only for high beam, as more and more drivers are complaining about the increase in dazzling car headlights and calling for them to be curbed.
Not a good combination: bluish LED headlights in fog, rain or wet roads
Light with high blue components (cold white light) not only dazzles more, but also has a higher scattering effect than yellowish light. This is the reason why the sky appears blue. The blue components of sunlight scatter more intensively on particles of a certain size than the red components do (rayleigh scattering). This means that if the road is wet, foggy, raining or snowing, bluish LED headlights scatter and dazzle much more intensively than the yellowish light from halogen headlights. Yellowish light therefore also penetrates fog more effectively and thus ensures significantly greater visibility ranges. But as mentioned above, the automotive industry argues that bluish light provides better color rendition, thus enhancing contrast (even if only in good visibility conditions), and that all this ultimately increases safety.
Pedestrians in danger
This development is becoming increasingly dangerous, especially for all unlit road users – i.e. pedestrians. They are more and more lost in the bright blinding LED light sea and are overlooked. As a result, municipalities and cities are trying to remedy the situation and are upgrading with even more bright LED light. The light/dark transitions are increasing even more and our eyes are becoming more and more strained or even more sensitive. Overwhelmed. it has been proven [2] that glare and excessive light/dark contrasts increase the number of accidents.
More safety means less light/dark contrast
In order to see and be seen better in road traffic, the opposite of strong light/dark contrasts is needed – namely uniform and at the same time moderate illumination of traffic areas. Especially from sidewalks. Because apart from pedestrians, all other road users always have their own lights with them. The least needed is actually the illumination of roads!
Modern LED technology is capable of doing just that. However, only if the components of illuminance, beam pattern, mounting height, mast spacing and traffic frequency are dimensioned and coordinated to meet requirements. What professional lighting designers can do.
Legislators share the blame for dangerously dazzling LED headlights
Of course, there are now high-tech LED headlight systems that use sensors to block out the light in the headlight beam in such a way that oncoming cars are not dazzled. Yes, even weather-dependent regulation is possible. But only a few people can or want to afford such costly systems. But for a normal LED headlights are enough for most (as you can see live). More and more new vehicles are being equipped with them. The safety aspect convinces drivers despite the hefty surcharges for such lights. As mentioned above, almost a third of new registrations are now SUVs and off-road vehicles. The higher position of the headlights makes such vehicles even more dazzling.
However, it is not only the energy-efficient LED with its glaring bluish-white and thus dazzling light that is to blame, but also the legislator. Recently, LED modules, of all things, have been exempted from the obligation to regulate luminous intensity (ECE regulation 48 within the "other regulations" regarding the use of LED modules). The approval of car headlights). The angle of inclination of LED headlights is therefore no longer automatically adjusted to the vehicle load by means of electronics in order to avoid glare. This special regulation for LED headlights saves vehicle manufacturers millions of euros. Despite the savings, hefty surcharges of well over 1000 euros are demanded per vehicle for equipping with LED headlights.
But there’s more: the regulations for "automatic headlight cleaning systems" have been relaxed. Such systems are very useful for bright headlights. The dirt on the glass covers of the headlights scatters the light and causes glare. The brighter the lamps installed in the headlights, the more intense the scattering effect. But at present, only those vehicles whose headlights emit more than 2000 lumens of luminous flux (lumen is a measure of brightness) must be equipped with such a cleaning system. What do the manufacturers do: they deliberately reduce the luminous flux so as not to exceed the 2000 lumen limit, thus saving on the cleaning system. But just under 2000 lumen are still enormously bright. And so the impurities on the headlamp lenses scatter the light and there is a lot of glare. Even minor impurities are sufficient here.
We lack any understanding of why these special regulations have come about. Some well known german car companies still have at least the headlamp leveling in their program. Even if in individual cases at enormously high surcharges. The situation is different with cleaning systems: at least one well-known major German car manufacturer no longer has such systems in its range – not even at extra cost.
How about driving slower?
We from godfathers of the night find this development in any case highly questionable. LED headlights do offer greater safety, but only for the driver. The safety of one person is at the expense of other road users, who are dangerously dazzled by the bright LED headlights.
bend lighting and other high tech around the modern LED headlights definitely helps to drive safely. One sees more. Dangerous spots are detected more quickly and reliably. One feels safer. But this is exactly what leads to faster driving. Studies have shown that people drive much faster at brightly lit intersections than at unlit ones. The actual plus in the form of more brightness is therefore reduced or even completely compensated for by faster driving.
Maybe it would be better for all road users not only to find very moderately and evenly illuminated traffic areas – but moreover to simply drive slower everywhere and all the time. In this case, the yellowish, significantly less dazzling headlight is easily sufficient.
Note: xenon light
in principle, the above also applies to the widely used xenon headlights. These have a similarly high luminous efficacy (so also about twice the brightness or. Lumen like a halogen lamp in comparison). However, the color temperature of xenon lamps is not as high as that of the LED lamps currently used in vehicles. Xenon lamps have a color temperature of a good 4000 kelvin (neutral white light), while LED lamps have a color temperature of 6000 to 8000 kelvin (cool white/daylight white). LED headlights therefore have a much more dazzling effect on the human eye than xenon headlights. Newer generations of xenon lamps have reduced mercury content and also contain sodium, which results in a noticeably more yellowish light (well below 4000 kelvin).
[2] pauen-hoppner ursula and hoppner michael, 2018. Lighting and safety: public lighting FGS berlin, punkt 4..
In addition, among others, also here: "publication of the german lighting technology society (litg) e. V.,outdoor lighting committee