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Compared to its Mar 2016 article, the Nov 29 2018 article by the Insurance Institute for Highway Safety proclaims that "headlights improve, but base models leave drivers in the dark" and are dreadfully too dim. Picture is from NPR.

Just over half of 2018 model vehicles IIHS evaluated are available with headlights that do an adequate job of lighting the road at night and limiting glare for oncoming drivers, but most good-rated headlights are optional or bundled with features that can raise the price of the vehicle.

In addition to overhead lights, why not illume (not a typo. I'm using this for it's shorter) from the ground like airport runways do?

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Such outdoor lighting can be recessed into the ground, to further prevent any collision between vehicles and the light bulbs.

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    $\begingroup$ Is the answer not in your username? Light pollution would be another problem. I think BMW had a better solution years ago: use a fluorescent die in the road marking paint and use UV headlamps on high beam. The markings would light up beyond the oncoming traffic. These would work through fog too without glare. $\endgroup$ – Transistor Jul 20 at 21:13
  • $\begingroup$ The junction beat me to it. Airport lighting does not improve pilots seeing runway, but rather identify where runway is for pilots. $\endgroup$ – StainlessSteelRat Jul 20 at 21:25
  • $\begingroup$ @Transistor Is overhead lighting cheaper than ground recess lighting? $\endgroup$ – AYX.CLDR Jul 20 at 21:27
  • $\begingroup$ Because cars don’t approach from a height... $\endgroup$ – Solar Mike Jul 20 at 21:27
  • $\begingroup$ Overhead lighting doesn't require digging up the roadway itself. It's already covering sewers, power, telecoms, etc. and would require a load of work on every resurfacing. Cat's eyes can be popped in from the top. $\endgroup$ – Transistor Jul 20 at 21:35
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I would think because airports are really well maintained while regular road lights get covered in dirt, sand, mud, debris, and snow. Also, vandalism is more difficult when the lights are higher up than when they are at ground level.

Functionally, it also makes sense for airport lights to point up since the planes are looking down. I don't think airport lights are meant to actually illuminate things on the runway either so they don't need to point at the ground.

Whereas for road lights it makes sense to point down since you are lighting the ground with a cone of light that gets larger the farther it goes. Upward facing roads light wouldn't have anything to reflect the light off of back towards the ground so it would take a lot more lights. Have you ever noticed upward pointing ceiling lights indoors? They often (always?) have a reflector so the light reflects back towards the ground. Just reflecting off the ceiling isn't enough sometimes. Compare this with outdoors lights where you're trying to light a much larger area and have nothing but a non-reflect, open sky above the light.

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In ground lighting is more expensive and requires the light source to be able to be run over by all vehicles that use the road, including very heavy vehicles. Such lighting only acts a point source of light that illuminates a small area on the ground as most of the light goes out into space. Care would be need to ensure the in ground lighting did not produce glare that would blind drivers.

In most urban and heavily trafficked areas, overhead street lighting is used. The benefits of this is minimal glare for drivers, light goes downwards and illuminates an area on the ground, were the illumination is required.

In less trafficked regions, drivers can use the car's high beam lights.

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