The Advanced Snow Plow system that Caltrans used as a test on Interstate 80 near Donner Summit had four miles with embedded magnets. This cost about $25,000/mile in '98.

The full description of the system can be read at https://path.berkeley.edu/sites/default/files/advanced_snowp...

Alaska uses GPS for their precision plowing - https://www.truckinginfo.com/329914/how-alaska-dot-uses-gps-... . Note that to get the 2" precision you need high quality GPS receivers.

> The trucks have two GPS receivers mounted atop the cab. These receivers cost about $10,000 each, Shankwitz says. "That's probably why this hasn't been deployed in many other areas; it's just too expensive and most applications do not require that level of accuracy."

> The two-centimeter accuracy actually comes from a third receiver -- a high-precision, stationary ground-based receiver perched atop a microwave communications tower in nearby Valdez. It's accurate to within millimeters and it acts as reference receiver for the plow-mounted systems.

I don't see this being standard on self driving cars.

That said, ground penetrating radar is being looked at and appears to be a lower price point. https://phys.org/news/2016-06-vehicles-high-precision-advers...

It's called differential GPS. However the new block of GPS sats have higher accuracy without the need for the (multiple) expensive receivers.

However, I'd argue the lanekeeping and "where am I" problems this stuff solves is dwarfed by the common sense and logical reasoning & recognition problems.

I don't see why not. We have centimeter-level GPS. It's true you maybe can't always rely on GPS signal being there, but you could also install devices on traffic lights that would allow cars to precisely locate themselves at intersections, so they stop at the correct position, etc.

What I think is that self-driving cars may also force us to confront ways in which real-world driving environments are inadequate, so that we can make them more adequate. For example, there are intersections where stop signs (or other signs) are present but not visible. Humans know they have to stop there, so they stop anyway. Self-driving cars could systematically find and report these locations, and might get the city to do something about them.

I also picture the moment a lot of cube satellites are above broadcasting internet across the globe 24hrs a day combined with millimeter gps combined with 5g cellular technology we could do a reasonable job of driving cars anywhere.