Embedded road lighting seems like a maintenance nightmare TBH, I think they trialed on one of the highways here ten years ago but didn't really go anywhere. I actually would like to see a return of illuminated road signs though. They used to be commonly used here but have pretty all been removed by now and replaced with reflective sheeted aluminum.

The city streets had small backlit streetblades that were incandescent. The keep right of median signs looked to be backlit with fluorescent or even low watt MV. The overhead highway signs had HO fluorescent or MV front lighting.

Lighted road signs: Right!? In the PNW, it is rainy, dark and gloomy here. The DOT I work for officially abandoned maintaining the lighted road signs saying that "retro-reflective is better" BS! Just stupid upwardly-mobile bureaucrats trying to pad their resumes with "I saved the city $xxx,xxx"

We had lane-by-lane lighted road signs. On a dark, rainy, gloomy night driving on a curving 3 lane road for example, you could see the lighted signs, 3 of them, indicating that the left lane only for left, middle lane is for thru, the right lane right turn only. Now, car headlights can't illuminate retro-reflective signs on a curve (especially since our DOT also became too lazy to square retro-reflective signs to the approach of cars, very important for this kind of sign) and you need to make last-minute decision in an area you may not be familiar with.

TBH the USA is circling the drain, at least from where I am. Nobody cares about maintaining all of the good stuff we had for decades.

As for the in-road lighted markers, we tried several versions, 2 types I was around for were amber LED buttons, one had an inductive power transfer module, which seemed like a good idea (even to me), embedded deep into the road and an LED module that was completely sealed sitting above the inductive module. It would light the LED module just like a Qi charger. The 2nd kind I saw had a cable going in and out of it. The results for both were very poor: Not only did they fill with water in less than 6 months, but they created potholes in our asphalt. Even our crazy DOT gave up on these!

The ones that Shanghai used are solar buttons, looked similar to what we used in Seattle, but no wiring. I was in Shanghai the first few weeks these buttons were new, very impressive. A year later, the same buttons were 99% dead, but a few still dimly glowed....reminded me of those cheap solar yard lights (don't get me started!) Imagine how much stuff ends up in the garbage! China has been filling their landfills at a 300-400% of planned rates for the last 10 years.....huh, I wonder why? Where's a tree-hugger when you need one?

Some of the road signs we have in extremely rural areas have solar panels either on top of the pole or nearby to power a light that illuminates the sign.