After nearly a decade of petitions, the NHTSA is giving the OK to ADB (Adaptive Driving Beam).
ANDREW TARANTOLA: The first headlights to adorn automobiles weren't all that much better than squinting real hard and hoping that any cows in the road had the good sense to move out of your way. The dim light cast by early kerosene oil and acetylene gas lamps made most travel after dark a fool's errand. Today, of course, the latest generation of headlights work much like modern movie projectors, with tightly packed arrays of pixelated headlights blinking at up to 5,000 times a second, allowing drivers to essentially use high and low beams simultaneously.
Until very recently, however, cutting-edge features like that weren't allowed on vehicles sold in the US due to an NHTSA regulation set in the '60s, but thanks to a multiyear lobbying effort on the part of Toyota, those regulations changed this last February. America's roadways are soon to become a bit brighter and a whole lot safer. The first electric headlights appeared on the 1912 Cadillac Model 30 and became mandatory equipment across the nation within a decade.
The first split-intensity headlights offering separate low and high beams wouldn't be included in a vehicle's OEM design until 1924, and the floor-mounted switch that controlled him wouldn't be invented until three years after that. There's a full decade of people having to get out of their cars just to turn their headlights on. The widespread adoption of sealed beam headlights in the mid-'50s proved a massive technological leap, while the first halogen light, which would quickly become the next global standard, debuted in 1962.
Halogens at that time were about as popular in the US as the metric system. We still preferred tungsten incandescents. That changed with the passage of the Motor Vehicle Safety Act of 1966 and the formation of the National Highway Transportation Safety Authority in 1968. These new rules, along with the formal adoption of Federal Motor Vehicle Safety Standard Number 108 that same year, they took the existing hodgepodge of state-level vehicular regulations and federalized them. In short, incandescent bulbs were out, and sealed beams were in.
The '80s saw US regulations expand out from exclusively sealed beam technology to allow for replaceable bulb headlamps, which the European market had already been enjoying for a number of years. The ability to swap out a bulb rather than replace the entire headlight unit, combined with recent material advances in lamp lens construction, drastically reduced the cost of making and operating headlights. By the '90s, halogens themselves had fallen to the wayside in favor of modern xenon and LED lighting technologies.
The 21st century has seen further advances not just to the lighting technology itself-- hello halo headlights-- but also to the control systems that direct the beams. Due to differences in their relative transportation regulations, European drivers enjoy slightly more advanced technologies than their American counterparts. Because standard 108 defined headlights is only having high or low beams, it tacitly excluded all of the technical advances that followed, specifically adaptive driving beam, or ADB, headlight systems, such as what are found on Audi's matrix LEDs, Lexus's BladeScan system, or Ford's adaptive front-lighting system-- none of these you will find operable stateside.
Yet ADB systems have been available in the European, Canadian, and Japanese markets since the technology's debut in 2004, though, technically, the 1967 Citroen DS did also feature headlights that swivel and sync with the steering, but it's not really the same thing. It would be more than a decade, not until Toyota's 2015 petition, before the NHTSA would even consider allowing their use in the North American market. In fact, it took another three years for the agency's investigation to wrap up, and it wasn't until February of 2022 that the NHTSA actually amended the regulation.
Broadly, ADB are headlights that actively adapt to the prevailing weather conditions and around obstacles like rain, snow, and oncoming traffic. Outside of the US, for example, Audi offers its digital matrix LED headlights, LEDs arrayed in a grid pattern and granularly controlled by a central processing unit called a DMD, or digital micromirror device. They operate a lot like the digital projection technology that they're based on. The light produced by the LEDs is reflected by an array of more than a million micromirrors, each of which measures just a few hundredths of a millimeter.
As these mircomirrors flutter in an electrostatic field, oscillating up to 5,000 times a second, they can expertly bend, brighten, and dim or mask specific portions of the headlight beam. Those masked areas are where the light isn't bouncing off of falling water or clearing into the eyes of other drivers. What's more, the system will project dynamic animations onto nearby surfaces. Think of it as a treat. More practically, however, the system can angle the beams to illuminate farther into turns and highlight pedestrians walking on the side of the road without blinding oncoming traffic.
Ford's high-resolution adaptive front-lighting system, which debuted in Europe this past August, offers similar capabilities. The company notes that roughly 40% of accidents occur on UK roads after sundown. Glancing down at bright infotainment displays while on dark roads can temporarily blind drivers, so Ford's headlights will instead project speed limits, navigation cues, and road hazard warnings onto the road itself.
Mercedes's digital light system, similar to Audi's, uses three LEDs in a thumbnail-sized array of 1.3 million micromirrors mounted in each headlamp to precisely attenuate the beams. According to Mercedes, that fidelity enables its high-beam assist to function two magnitudes more precisely in excluding oncoming traffic than conventional 84-pixel arrays. On the other end of that spectrum, Lexus's has Blade-Scan high-definition headlights, which debuted in Asian markets in 2019, only utilize 24 LEDs per headlight. Rather than an array of micromirrors, Lexus uses a pair of rapidly spinning mirrors to direct their light through the lens and onto the road. According to the company, this allows the system to aim within 0.7 degrees of accuracy and detect pedestrians at the roadside more than 180 feet away.
Unfortunately, for as cool as these capabilities are and as technically legal as they are, American drivers still have to wait a bit before they come stateside. Namely, that's because the NHTSA must now devise a set of testing requirements by which to measure and regulate the adaptive headlights under the revised standard. In the short term, it means we'll likely see more new vehicles equipped with ADB-capable-but-disabled hardware that can be activated over the air later on once the regulations have firmed up.