Why are modern car headlights so bright? How to prevent dazzle

Why are modern cars’ headlights so bright? We explain what’s causing more drivers to be dazzled at night and how to prevent it

Are car headlights getting brighter? Ask around, and you’ll find it’s a common grumble among anyone that drives, especially those that frequently take to the road first thing in the morning or at night.

They’ll tell you that on an unlit road, especially one with crests or undulations, oncoming traffic can leave them feeling as if they can’t see.

During the winter months, the problem is exacerbated. Fewer daylight hours mean cars spend more time with their lights on. And the latest technology on modern cars has introduced superior lighting power to even the average family car.

While that’s great for any driver of a car with powerful lights, it’s not so safe for drivers of oncoming vehicles. They can find themselves blinded by the brilliant light from the latest systems.

Is there anything dazzled drivers can do? And will headlights continue to get brighter?

What’s the problem?

It’s a fact that car headlights are getting brighter. The motor industry is continually boasting about how it has improved lighting performance, to keep drivers safe. Meanwhile, eye specialists say the downside is that this actually impairs the vision of increasing numbers of drivers in oncoming traffic.

At the same time, as drivers age the eye’s lens and cornea effectively become misty, and as bright light in shone through them, drivers suffer something called ‘disability glare’. Studies have shown it can take up to 10 seconds to recover from the phenomenon.

According to police data, accident investigators report ‘dazzling headlamps’ as an influence in 10 fatal crashes, nearly 70 serious accidents and more than 250 other accidents.

Bicycle lights can be just as dazzling

Given the improved performance of bicycle lights, they can be just as dazzling for oncoming traffic. Especially if the rider hasn’t correctly positioned the light to ensure the light beam isn’t in the direct eyeline of oncoming drivers.

Is there a quick fix for drivers?

Happily, there is. Professor John Marshall, of University College London, says anyone can buy and use special clear glasses, even if they don’t need prescription lenses. These have a coating on the lens to absorb ultra violet light and prevent glare when driving at night. They are relatively inexpensive, from £10, and any optician will be able to advise what best suits a driver’s needs.

Other preventative measures

If your car’s windscreen is dirty, either on the inside or outside, the dirt will cause light to refract, making it harder to see where you’re going. It’s also important to ensure your car’s headlights are correctly adjusted and the bulbs aren’t aged with use. And don’t forget to take an eye test regularly – at least every two years, according to optometrists.

What are car makers doing?

Ford is going to great lengths to make its latest family cars safer for owners and other drivers alike. Its new Glare-Free Highbeam adjusts the headlight beam angle and intensity to one of seven settings according to speed, ambient light, steering angle, distance to the vehicle in front and windscreen wiper activation. Find out more about it, in our earlier blog post. Other mainstream car makers are developing similar systems. However, as anyone who has used them will know, they aren’t foolproof.

From halogen lights to Xenon systems

Why are modern cars’ headlights so bright? We explain what’s causing more drivers to be dazzled at night and how to prevent it

Traditional halogen bulbs made way for brighter Xenon, or high intensity discharge (HID) lights in the early ‘90s. BMW first fitted the system to its 7 Series flagship. It was widely praised by users for the brightness of the light and associated reduction in driver fatigue. The bulbs also lasted longer, for around 2000 hours.


Why are modern cars’ headlights so bright? We explain what’s causing more drivers to be dazzled at night and how to prevent it

First fitted to the Audi A8 luxury saloon in 2004, engineers and designers alike prefer to use light-emitting diodes (LEDs) when making modern cars. That’s because they use less power than Xenon units, give more freedom for styling the body parts, as they’re so compact, and the light produced is bright.

There are other advantages. The light can be manipulated, such as when adjusting the pattern of the full beam to allow for oncoming traffic or pedestrians. And they are claimed to last for comfortably more than 5000 hours.

The latest headlight tech: matrix laser lights

If you thought LEDs were bright, think again. Audi was the first car company to fit laser lights to a car, in 2014. The technology sounds like it belongs in a Star Wars movie. But high-intensity laser diodes are fitted to the Audi R8 sports car and light the road ahead when the driver selects the main (full) beam pattern.

The laser system is claimed to offer twice the range of even the brightest LED. Its laser diodes create a bright blue light that has to be filtered by phosphor converters to make it white and harmless to the human eye.

In the future, Audi engineers hope to combine laser lights with driver aids to help pick out pedestrians, project graphics – to help indicate the width of the car – or pick out road signs.

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