Adaptive headlights

Adaptive headlights are designed to make driving at night safer by increasing your visibility around curves and hills. During the evening and nighttime, driving around corners – even at safe speeds – can be dangerous due to low visibility. Potential obstacles and hazards that are visible in normal conditions may be obscured once the sun sets. When negotiating a bend in the road, standard headlights continue to shine straight ahead, illuminating parts of the road that you do not need to see and leaving the road ahead of you in the dark.

Adaptive headlights, on the other hand, turn their beams according to your steering input, lighting up your vehicle’s path, and increasing visibility in low-light conditions. In addition to helping you see around poorly lit curves, adaptive headlights can also make cresting hills safer. When a vehicle with standard headlights crests a hill, the headlight beam temporarily points up towards the sky. This not only makes it difficult to see the road in front of you, but also makes it difficult for oncoming motorists to see you coming. In contrast, with the help of a self-levelling system, adaptive headlights consistently direct headlight beams down towards the road. For more information on how the self-levelling system works, please see the section below entitled How do adaptive headlights work?

Adaptive headlights are an example of driver assistance technology. This means they are designed to complement your safe driving practices by offering help when you need it. Adaptive headlights cannot warn you of objects in the way, but they can make it possible to see potential dangers sooner or more easily. Adaptive headlight technology goes by a few other names, including active headlights and adaptive front-lighting systems. Despite the different names, however, each system has the same fundamental design and function.

Even though fewer motorists are on the road after sunset, according to the National Safety Council, 50% of traffic deaths happen at night (NSC 2023). Adaptive headlights are helpful whenever you are driving on winding roads at night, during twilight, or in other low-visibility conditions. They can address a variety of potentially dangerous situations, including:

• An animal lingers on the road just around a poorly lit curve.
• An oncoming vehicle negotiating a sharp curve is drifting into your lane.
• Another motorist has stopped his vehicle at the side of the road, just beyond a corner.
• You are on a narrow road at night cresting a hill, but cannot see if another vehicle is coming in the opposite direction.

By pointing your vehicle’s headlights in the direction your car is moving, adaptive headlights increase your ability to see what is in front of you, whether it is around a corner or over a hill.

¹ Like regular adaptive headlights, the range of motion of the cornering lights also varies by manufacturer. In addition, safety technology engineers develop and perfect cornering light systems, so the speed of activation and the range of lighting may differ from one manufacturer to another and from one phase of technological development to the other.

An adaptive headlight system is comprised of several sub-components that are monitored and controlled by an electronic control unit (ECU). Three sensors monitor the wheel speed (the speed of rotation of the vehicle’s wheels), yaw (motion along the vehicle’s vertical axis), and steering input of the vehicle (the angle at which the driver has positioned the steering wheel). These data are interpreted by the ECU which then sends directions to small motors attached to each headlight. These motors will move the lights to the degree specified by the electronic unit. Current adaptive headlight systems can turn up to 15 degrees per side, for a total range of 30 degrees, substantially increasing your range of visibility. Furthermore, safety technology developers are always improving on this range of motion, so adaptive headlight systems may be available today or in the near future that can illuminate an even wider section of the road ahead.

Most adaptive headlight systems also include a self-levelling system. This system is designed to prevent your headlights from momentarily pointing too far up or too far down when your car goes over hills or large bumps. A self-levelling system includes a level sensor that determines if the car is tilted forward (when driving downhill) or backwards (when driving uphill). The headlights are then moved up or down to correct for the vehicle’s forward or backward positioning.

Some adaptive headlight systems are complemented by cornering lights. These automatic systems are designed to increase visibility during very tight manoeuvres undertaken in low-light conditions. Cornering lights illuminate the sides of the vehicle when you are negotiating hairpin turns or parking, and can illuminate up to 80 degrees of space¹  by the side of your vehicle. These lights will then automatically turn off when the vehicle has finished turning.

Adaptive headlights are still a relatively new safety technology, so there is limited data about their effectiveness. However, the Insurance Institute for Highway Safety (IIHS) in the United States has defined crashes where adaptive headlights would be relevant as all night-time front-to-rear collisions, single-driver, and same-direction side-swipe collisions. The IIHS also limited the group of relevant crashes to those that occurred while the driver was negotiating a curve. Given this, the IIHS estimates that adaptive headlights could have helped in 143,000 crashes in the United States in 2008, including 31,000 that resulted in injury and 2,553 that were fatal (IIHS 2008).

Since adaptive headlights are a relatively new safety technology, there is a limited amount of data to measure their effectiveness. The Insurance Institute for Highway Safety (IIHS) has defined crashes where adaptive headlights would be relevant as all night-time front-to-rear collisions, single-driver, and same-direction side-swipe collisions. IIHS also limited the group of relevant crashes to those that occurred only when the driver was negotiating a curve. Given this, IIHS estimates that adaptive headlights are relevant in 142,000 crashes per year in the United States, including 29,000 that resulted in injury and 2,480 that resulted in death (IIHS, 2010).

Adaptive headlights also benefit other motorists on the road. For example, when turning around a bend in low-light conditions, standard headlights will temporarily point directly at oncoming traffic. Unlike standard headlights, adaptive headlights are designed to point more directly at the road, thereby reducing the likelihood that oncoming motorists are temporarily blinded by the headlights of others. Also, since it is unlikely that adaptive headlights will ever point directly at another motorist, the lights within adaptive headlights can be brighter and still be safe.

Many adaptive headlight systems feature bi-xenon lights. Emitting a slightly blueish tint, these lights are brighter than standard lights and offer a clearer, more distinct view of the road ahead. Also, the ionised gas used in bi-xenon lights is more energy efficient than typical halogen bulbs, which makes bi-xenon lights last longer.

Yes. As with many other safety technologies, realizing the potential benefits of adaptive headlights depends largely on whether drivers understand the design limits and intended function of the technology and can interact appropriately with it. Adaptive headlights are designed to illuminate the road in front of you in conditions of low visibility. The system is not designed to alert you in any way of obstacles or potential road hazards. In addition, while adaptive headlights can significantly increase a driver’s range of visibility, this range still has limits. What this means is that while negotiating curves sharper than 15 degrees, you will have to slow down further in order to maintain a lit view of your path.

The Transportation Research Board’s 2015 study showed “significant crash reductions occur with in-curve warning signs beginning between 4,000 and 7,000 AADT [Annual Average Daily Traffic] across all crash types on isolated curves.” (TRB, NCHRP 03-106 Final Report, 2015). Nevertheless, there are still many curves in roads that exceed 15 degrees, even on fast roads like highways. When safely negotiating a curve requires a reduction in speed, there will be a sign alerting you of both the approaching curve and the proper speed at which to take the curve. In low visibility conditions, you may have to reduce your speed further. Driving a vehicle equipped with adaptive headlights does not make speeding around corners any safer, so you are always urged to respect the posted speed limits and to reduce your speed when going around curves.

Your adaptive headlights may work perfectly and illuminate an obstacle you would not otherwise have seen, however you must still be able to react appropriately to that obstacle. If your reaction time is delayed for some reason (e.g., fatigue, distraction, excessive speed, inattention, or intoxication), then there is a very real danger that you will not be able to manoeuvre safely around hazards on or near the road, regardless of how much notice you get.

Feedback from drivers who own cars with adaptive headlights demonstrates a disturbing increased willingness to drive at night or at higher speeds (IIHS, 2008, Braitman et al., 2010). The sense of security that safety features inspire should not lead you to drive in ways or in conditions you would normally not feel safe driving. Particularly, given the crucial role of the driver in avoiding obstacles illuminated by adaptive headlights, motorists should remember they are always encouraged to use safety technologies to complement their responsible driving practices, and not as a reason for driving less attentively or more recklessly.

Adaptive headlights will not affect any other aspect of your driving experience. The advanced headlight system is a quiet feature that is designed to be non-intrusive. Adaptive headlights automatically disengage when a vehicle is stationary or moving in reverse, so you do not need to be concerned about turning the feature on and off.

That being said, adaptive headlight systems can still be turned off. You can turn most adaptive headlight systems on or off from within the vehicle by moving a switch between OFF and AUTO. There is also typically an adaptive headlight indicator light on the vehicle’s dashboard to remind you of whether the system is active or not. For more detailed instructions about turning adaptive headlights on or off, you may consult the owner’s manual of your vehicle. However, you are encouraged to use good judgment when deciding to turn off any of the safety features on your vehicles.

Adaptive headlights are still relatively new, and not enough data have been collected about their effectiveness to encourage their standardization. The advanced headlight system was first introduced to the North American market in 2003. Since then, it has most often been offered as an optional feature on luxury brands, although some manufacturers offer adaptive headlights as a standard feature on some higher-end models. However, adaptive headlights are being made available on an increasing range of vehicle makes and models.

Since adaptive headlights are relatively new, the price of installing the sophisticated system is still high; an after-market system can cost upwards of $1,000. However, as more vehicle makes and models begin to feature adaptive headlights as either optional or standard, the price of the system is likely to change. There is also no anticipated effect of adaptive headlights on fuel consumption.