TrackedPRT

I found a few similar ideas on halfbakery (in fact, it's how I found the site), but I they weren't quite the same. If this seems like a repeat at first, please bear with me and thanks for your patience.

Basic Concept
Erect a series of “conveyor belt” tracks above existing roadways. The tracks would run about 20 feet above the roadways, in sections about 20 to 30 feet long. Each section of track would have its own motor and radio receptors and move independently of the others. Multiple lanes, turnarounds, etc. could be accomplished with branches in the belts, and paths from one lane to the other spaced at regular intervals.
Vehicles would consist of a ridged bottom that fit to ridges on the belts, and a mechanism for locking into the sides of the belt. Each vehicle would have a transmitter that would transmit desired speed and direction to the upcoming sections of belt.
Notes
Like conventional vehicles, some would be for mass-transit, but family or even individual vehicles would be allowed on the tracks. Track standards and vehicle requirements would be publicly available, to encourage innovation while preserving safety standards.
Emergency and police vehicles would have override codes to allow them to shunt all vehicles to the slow lane, for instance, or stop a particular section of track to apprehend or assist a driver.
The scaffolding for the tracks could double as support for streetlights, telephone lines, cable, and other infrastructure-related items.
Transmitting the desired direction would affect only the branches of track immediately in front of the individual vehicle. Desired speed would be transmitted further ahead and, taking into account the desired speed, the speed of other drivers, minimum and maximum speeds, the tracks ahead would incrementally speed up or slow down to prevent a “jolt” between sections.
Variations in terrain could be mitigated by varying the height above ground level, where the amount of power required to descend and/or ascend would exceed the effort of, for instance, keeping the track level over a small valley or dip in the terrain.
Home and commercial parking would ideally be on roofs or a higher floor. The basic configuration would be a “loop”, where the driver could pull in and set the steering to the inside, so that as other drivers enter, the first vehicle would not venture back out onto the roadway.
Benefits
By decoupling the energy source from the vehicle itself, more opportunities emerge for alternative power. For example, it would be totally impractical to add a windmill to a car, but having windmills power large sections of track could prove quite reasonable. Likewise for solar, hydro, nuclear or hydrogen energy sources.
By putting the tracks above existing roadways, existing infrastructure can be preserved, at least in the short term, and probably in the long term for transportation to places without track, or for oversized loads.
Accidents between vehicles are prevented because the vehicles cannot hit one another. (an interesting note: drunk drivers would probably do nothing worse than get lost). Accidents involving pedestrians are prevented because the tracks would be inaccessible to pedestrians.
Individual vehicles could be kept very inexpensive, since the majority of the moving parts and electronics would be part of the tracks themselves. The vehicles would essentially be sleds with a remote control for a steering wheel.
Other desirable transportation technologies such as traffic control, traffic prediction and automated driving, all of which are terribly complex for today’s road vehicles, would be much easier given the track system and the data collected, of necessity, by the tracks.
The cost of the tracks themselves, while daunting at first, would gradually be offset by diminished wear and tear on the conventional roadways. Also, tracks could be manufactured offsite, so that construction would be just assembly. Thus, there would be less construction-related traffic delays, and fewer workers needed on-site. Standard track configurations would also benefit from economies of scale not found in conventional roadway construction, which is more constrained by terrain conditions and configurations.
Implementation
The obvious impediment to switching to a track system would be lack of infrastructure. Ideally, the system would start out as a local transport system, for instance for a large college campus or an amusement park. From there, it could be implemented in a city center, and then gradually spread to connect cities to one another, and then to smaller towns and communities.
In the short term at least, the tracks above would mirror the roads below. Thus, a two-lane road would probably require two lanes of tracks, and the tracks would initially go to those destinations that the roads were going to, as well.
The track itself could be funded by taxes. Initially, of course, there would need to be significant investment of public funds. Ideally, though, registration fees for the track vehicles would provide funding for the maintenance and expansion of the track system. With the use of alternative energy sources (which can now be large and stationary), the fees should be offset by the much lower cost of the vehicles themselves, making the track system financially desirable for individual users.