They are a good idea once the technology gets totally sorted-out.
In my Region (like a county), the transit system has a "light rail transit" system that was put in place a few years ago. I fuckin' hate it. These massive trains all over the city with 2 or 3 passengers half the time.
Self-driving vehicles would be way better. They need to hook up to chargers by themselves. They need to be in several sizes like 2 passengers, 4 passenger, 6 passenger...whatever. They would be "on demand", just like taxis.
There would still need to be some routes that larger vehicles would travel, like along the main downtown streets, etc..
But having large buses/trains going around the city nearly empty, and therefore wasting energy, would be a thing of the past.
