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Comment by michaelt | Hacker News Reader

I got an airport transfer in a car with smart headlights a few weeks ago.

It was pretty neat - when the road was quiet it lit the road quite broadly, but when there was oncoming traffic it would deactivate the 'pixels' that could have dazzled the oncoming driver. I also got the impression it cast extra light at road signs (although maybe the route I was driven just had very well lit signs)

My country gets dark at 4pm at this time of year, so driving in rural areas involves a lot of switching between main beam and dip beam - and getting mad at oncoming drivers who don't switch early enough. So these smart headlights seem like a good thing!

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While I bet they work brilliantly for the driver of the car, for the oncoming traffic it's really annoying. It leaves light spots in my eyes every time I drive in the night and encounter cars with such headlights, as it doesn't deactivate those 'pixels' quick enough for me not to notice. Overall it might be an improvement, but it depends on your situation.

As for extra light at road signs, I believe I've read somewhere that newish signs have ability to reflect near ultraviolet as visible light, and this makes them extra reflective for headlights with ultraviolet range, more so then what you would expect for the given visible light that you see. Although I'm no expert in this and not sure if that actually the reason for why some signs popout so much.

Yes, lots of modern road signs that are put in have a flourescent coating on them. [1]

[1] https://www.3m.com/3M/en_US/road-safety-us/resources/road-tr...

Signs 'pop' because they are very effectively retro-reflective (https://en.wikipedia.org/wiki/Retroreflector). The brighter headlights with a wider beam would be casting a moderate amount of light on the sign, which causes it to light up brightly in contrast with the surroundings.

The ones in the UK can be so effective that sometimes I have to switch off my full beams so I don't get blinded by the signs (and I'm not driving a new car with fancy headlights).

Headlights are also slightly biased to the nearside of the car so more light is cast upon road signs and the side of the road.

The cool thing about smart headlights is that they don't have to dim on the nearside of the car when there's oncoming traffic, so you get more brightness on the side of the road. Regular headlights have to dim both lights equally.

Especially good for pedestrians and bikers which aren't detected by their shitty smart features.

And the drivers long since forgot how to actually do it manually

I did know someone who didn't know that that you are supposed to dip your headlights when other people could see them. They thought all the people flashing their headlights at them were just being friendly!

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