“Possibly microchips embedded in the paint of the lane-demacation road stripes.”
This was the way “intelligence highways” were conceived 20 to 30 years ago. The idea was to make the highway itself intelligent and communicating with vehicles. This was endlessly researched and never went anywhere because the cost was immense and not all roads could be upgraded. This approach was eclipsed by moving the intelligence into the vehicles themselves and leaving it out of the roads.
In a way, this is similar to the evolutionary path of communications. Initially you had monstrous central switches doing all the switching of phone calls. Then packet switching took over with highly distributed routers with packets containing information about where they wanted to get to.
How many years, how many doublings of performance/price ratio, since then???Cell phones are an obvious example of a technology which was easily envisioned - and easily dismissed on price grounds - long ago. Now every Tom, Dick, and Jane has a computer in his/her pocket, and the cost proposition looks quite different.