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Using Adaptive Headlights
Agency: Insurance Institute for Highway Safety
What are adaptive headlights?
When would adaptive headlights be useful?
How do adaptive headlights work?
How effective are adaptive headlights?
How do adaptive headlights benefit other motorists?
Do adaptive headlights have limitations?
How common are adaptive headlights on today’s roads?
Adaptive headlights are an active safety feature designed to make driving at night or in low-light conditions safer by increasing visibility around curves and over hills. When driving around a bend in the road, standard headlights continue to shine straight ahead, illuminating the side of the road and leaving the road ahead of you in the dark. Adaptive headlights, on the other hand, turn their beams according to your steering input so that the vehicle’s actual path is lit up.
Similarly, when a vehicle with standard headlights crests a hill, the headlight beams temporarily point upwards towards the sky. This makes it difficult for drivers to see the road ahead and for oncoming motorists to see the driver approaching. In contrast, adaptive headlights use a self-levelling system that points the light beam up or down, according to the position of the vehicle.
Adaptive headlights are also sometimes called active headlights or adaptive front-lighting systems.
Adaptive headlights are helpful when driving on winding roads at night, during twilight, or in other low-light conditions. They can address many potentially dangerous situations, including:
- An animal is standing on the road just around a poorly lit curve.
- An oncoming vehicle negotiating a turn accidentally drifts into your lane.
- Cresting a hill on a narrow road, you are unable to see whether another motorist is coming.
- As you round a curve, your headlights temporarily blind oncoming traffic.
Adaptive headlight systems are made up of several subcomponents that are monitored and controlled by an electronic control unit (ECU). The subcomponents include:
- wheel speed sensors that monitor the speed of rotation of each wheel;
- a yaw sensor that tracks a vehicle’s side-to-side movement, e.g., when turning a corner;
- a steering input sensor that monitors the angle of the steering wheel; and
- small motors attached to each headlight.
The data from the sensors are interpreted by the ECU, which then determines the vehicle’s speed, and the angle and length of the curve it is negotiating. The ECU directs the motors attached to each headlight to move the beam to the degree specified by the ECU. Most adaptive headlight systems can turn the headlights up to 15 degrees per side. Newer versions of the advanced headlight system have even larger ranges of motion.
Most adaptive headlight setups also include a self-levelling system. This system helps prevent headlights from pointing too far up or too far down when driving up or down hills. A self-levelling system includes a level sensor that sends information to the ECU about the vehicle’s position, specifically whether it is tilted forward or backwards. The headlights are then moved up or down to correct for the vehicle’s positioning.
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).
Adaptive headlights also benefit other motorists on the road. For example, when a vehicle turns around a bend in low-light conditions, standard headlights will temporarily point directly at oncoming traffic. This can lead to discomfort and temporary blindness for oncoming motorists. This problem is avoided with adaptive headlights, since their beams stay on the road and do not point at oncoming traffic. In addition, since headlight beams to not point at other motorists, it is safe for drivers who own a vehicle with adaptive headlights to use bi-xenon lights. Emitting a slightly blue-ish tint, these lights are brighter than standard lights and offer a clearer, more distinct view of the road ahead.
Yes. As with many other safety technologies, realizing the potential benefits of adaptive headlights depends largely on whether drivers interact appropriately with the system. This means to continue to drive safely and attentively. Driver behaviour like speeding, fatigued driving, or distracted driving can reduce the beneficial aspects of adaptive headlights.
For example, fatigued, distracted, and alcohol-impaired drivers all experience a decrease in their ability to react quickly to situations on the road. Adaptive headlights can help illuminate hazards sooner than they would have been otherwise; however, a delayed reaction time could make it impossible to safely avoid the hazard. Excessive speed can have a similarly detrimental effect on the possible benefits of adaptive headlights. When drivers negotiate a curve at a high rate of speed, they have less time to react to hazards that may be hidden around the corner.
Adaptive headlights do not compensate for unsafe driving or poor road conditions. Drivers must still take extra precautions when driving at night, and should continue to use safe driving practices at all times.
Adaptive headlights have only been in the North American market since 2003. They are most often offered as an optional feature on luxury brands; however, adaptive headlights are being made available on an ever-increasing range of vehicle makes and models.